Wednesday, February 22, 2017

Porting OpenWRT to ionik Wifi Cloud Hub

I will probably have to split this article into several parts, as I move along.

In the initial article (see I took a look at the hardware and started doing some basic hacking. However, I quickly ran into limitations and decided to try and port OpenWRT for the platform.

There are quite a few steps and preparations needed to do this, however, this is for documentary purposes only. You don't need to do any of the stuff below (except backup), you can just flash my OpenWRT firmware and be none the wiser. However it might be useful if you want to port it to a new device, I could not find any tutorial about this.

Step 0 - BACKUP

In case everything blows up you will want to be able to restore everything to the factory condition. I first reset the root password to 'admin' by going to this link:

This is not necessary now since some nice people have decoded the factory root password: 91657853.
Connect to the serial pads, log in as root.

I liked to have a Samba share so I could copy the entire file system. So type this inside the shell:

printf '\n[rootFS]\npath=/\nvalid users = admin\nbrowseable = yes\nwritable = yes\n' >>/etc/smb.conf

This creates a Windows share that can be accessed with admin/admin. Copy everything except /dev, /media and /sys to some local storage:
Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----         1/1/1980  12:00 AM                bin
d-----         1/1/1980  12:00 AM                etc
d-----         1/1/1980  12:00 AM                etc_ro
d-----         1/1/1980  12:00 AM                home
d-----         1/1/1980  12:00 AM                lib
d-----         1/1/1980  12:00 AM                sbin
d-----         1/1/1980  12:00 AM                tmp
d-----         1/1/1980  12:00 AM                usr
d-----         1/1/1980  12:00 AM                var
With a USB stick and an SD card inserted we can type 'mount' to see where these get mounted.

rootfs on / type rootfs (rw)
proc on /proc type proc (rw,relatime)
none on /var type ramfs (rw,relatime)
none on /etc type ramfs (rw,relatime)
none on /tmp type ramfs (rw,relatime)
none on /media type ramfs (rw,relatime)
none on /sys type sysfs (rw,relatime)
none on /dev/pts type devpts (rw,relatime,mode=600)
none on /proc/bus/usb type usbfs (rw,relatime)
mdev on /dev type ramfs (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,mode=600)
/dev/sdb1 on /media/UBUNTU_16_1 type vfat (rw,relatime,fmask=0000,dmask=0000,allow_utime=0022,codepage=cp950,iocharset=utf8,shortname=mixed,utf8,errors=remount-ro)
/dev/sda2 on /media/OS_X_Base_System type hfsplus (rw,relatime,umask=0,uid=0,gid=0,nls=utf8)

It seems sdb corresponds to the USB stick and sda to the SD card. There is an EFI partition (sda1) which gets ignored.
We need to do a block dump of the entire flash contents.

# dd if=/dev/mtdblock0 of=/media/UBUNTU_16_1/mtdblock0
16384+0 records in
16384+0 records out
# dd if=/dev/mtdblock1 of=/media/UBUNTU_16_1/mtdblock1
384+0 records in
384+0 records out
# dd if=/dev/mtdblock2 of=/media/UBUNTU_16_1/mtdblock2
128+0 records in
128+0 records out
# dd if=/dev/mtdblock3 of=/media/UBUNTU_16_1/mtdblock3
128+0 records in
128+0 records out
# dd if=/dev/mtdblock4 of=/media/UBUNTU_16_1/mtdblock4
3584+0 records in
3584+0 records out
# dd if=/dev/mtdblock5 of=/media/UBUNTU_16_1/mtdblock5
12160+0 records in
12160+0 records out

Now the flash contents are stored safely on our USB stick.
We could also copy the file system to the USB stick instead of using a network share: cp -RLf /etc_ro /media/UBUNTU_16_1/ionik/etc_ro

Entry points

We need to identify how the flash is partitioned:

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00800000 00010000 "ALL"
mtd1: 00030000 00010000 "Bootloader"
mtd2: 00010000 00010000 "Config"
mtd3: 00010000 00010000 "Factory"
mtd4: 001c0000 00010000 "MiniSystem"
mtd5: 005f0000 00010000 "Kernel"

  • mtd0: 0x00000-0x800000 entire flash contents
  • mtd1: 0x00000-0x30000 is the uBoot bootloader
  • mtd2: 0x30000-0x40000 stores the user-defined configuration
  • mtd3: 0x40000-0x50000 stores some internal configuration (WiFi registers?)
  • mtd4: 0x50000-0x210000 is the failsafe (recovery) firmware
  • mtd5: 0x21000-0x800000 is the normal firmware

How booting works

When the CPU starts up it goes to the first address inside the flash memory to look for an executable. It finds uBoot at position 0x00 and hands over control to that. uBoot then does some housekeeping and decides where to jump next.
In the case of this device, if the reset button is kept pressed while powering on, uBoot will jump to 0x50000 (mtd4), otherwise it will jump to 0x21000 (mtd5).

Normal boot
3: System Boot system code via Flash.
## Booting image at bc210000 ...
raspi_read: from:210000 len:40
.   Image Name:   Linux Kernel Image
   Created:      2013-09-09   8:53:17 UTC
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    6025942 Bytes =  5.7 MB
   Load Address: 80000000
   Entry Point:  8000c310
raspi_read: from:210040 len:5bf2d6
 Failsafe (minisystem) boot:
7: System Boot mini system code via Flash.
## Booting image at bc050000 ...
raspi_read: from:50000 len:40
.   Image Name:   Linux Kernel Image
   Created:      2013-03-11   6:20:33 UTC
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    1649876 Bytes =  1.6 MB
   Load Address: 80000000
   Entry Point:  8000c310
raspi_read: from:50040 len:192cd4

I don't know much else to tell you, this is all pretty new to me as well. Think of uBoot as "grub" on your computer.


It would be nice to be able to read and write to GPIO pins. I haven't made much progress here, or perhaps the system is limited in this regard. Here are my notes:

blue power on, not charging (yellow off), blue activity off(?), reset off # gpio r
gpio 27~22 = 0x28   ->            10 1000
gpio 21~00 = 0x7c81 -> 111 1100 1000 0001
above + led yellow (charge on):
gpio 27~22 = 0x28
gpio 21~00 = 0x7c81
reset pressed:
gpio 27~22 = 0x28   ->            10 1000
gpio 21~00 = 0x7881 -> 111 1000 1000 0001
failsafe mode, magenta(?) led on, yellow on, blue off
gpio 27~22 = 0x28
gpio 21~00 = 0x7c81
red led blinking # gpio l 9 1 1 10 1 5
led=9, on=1, off=1, blinks,=10, reset=1, time=5

Conclusion: wifi led (blue), power led (blue), charge led (yellow) seem to be hardwired, Red led is bit 9+1 of GPIO; reset is pin 10+1
There's also a low battery indicator that I was not able to read or write to.

Getting dirty - OpenWRT configuration

The first step is to retrieve the repository, set up all the tools and dependencies. I will not go into those details as they are a moving target.

We already know from the teardown that the CPU is Ralink RT5350F. Luckily, OpenWRT already provides this platform for us under the name rt305x.

Add the following entry into /target/linux/ramips/base-files/lib/ :

+ *"i.onik Wi-Fi Cloud Hub")
+ name="ionik-cloud-hub"
+ ;;

Then this under /target/linux/ramips/base-files/lib/upgrade/, under the ip2202 entry :

+ ionik-cloud-hub|\

Not sure how correct is that. I think this file controls how the original (factory) firmware does checksumming in order to get your "trojan" firmware accepted as an upgrade.

Then this under /target/linux/ramips/image/ :

+Image/Build/Profile/IONIKCLOUDHUB=$(call BuildFirmware/Default8M/$(1),$(1),ionik-cloud-hub,IONIKCLOUDHUB,Linux Kernel Image) 

....and a bit lower inside the file...

+ $(call Image/Build/Profile/IONIKCLOUDHUB,$(1))

I found out that - after a test build - my custom firmware only recognized 32M of RAM instead of the 64M that are available. So modify the CONFIG_CMDLINE parameter inside target/linux/ramips/rt305x/config-4.4 b/target/linux/ramips/rt305x/config-4.4 :

+CONFIG_CMDLINE="rootfstype=squashfs,jffs2 mem=64M" 

Specifying the network interfaces, I probably goofed on this but it still works, add the platform inside target/linux/ramips/base-files/etc/board.d/02_network :
@@ -142,6 +142,7 @@ ramips_setup_interfaces()
  "0:lan" "1:wan" "6@eth0"
+ ionik-cloud-hub|\

I wanted to flash the red LED when booting but it did not work. target/linux/ramips/base-files/etc/ :
@@ -138,6 +138,7 @@ get_status_led() {
+ ionik-cloud-hub|\

I also want the wireless to be up after booting since the 'router' lacks an ethernet port. This could be done in a better way, with a default password or one based on MAC. So from package/kernel/mac80211/files/lib/wifi/  you need to comment out the line that says 'option disabled 1'.

Then we need to add a file inside target/linux/ramips/rt305x/profiles called
define Profile/IONIKCLOUDHUB
kmod-ledtrig-netdev kmod-ledtrig-timer kmod-leds-gpio \
kmod-usb-core kmod-usb-ohci kmod-usb2 kmod-usb-net usbutils \
kmod-scsi-core kmod-scsi-generic kmod-fs-ext4 kmod-fs-msdos \
kmod-usb-storage kmod-usb-storage-extras block-mount

define Profile/IONIKCLOUDHUB/Description
Package set for i.onik Wi-Fi Cloud Hub
$(eval $(call Profile,IONIKCLOUDHUB))

Getting dirtier - DTS

This was the most painful part for me. To start off, create a file called IONIKCLOUDHUB.dts inside target/linux/ramips/dts.

I started by looking at routers with similar features and copied that file. I think I used some Western Digital WiFi HDD or something.

The DTS files describes the devices available for the Linux subsystem. The most important part however is the flash configuration.

Let's go into a quick walkthrough, I won't pretend to know what everything does:


#include "rt5350.dtsi"

/ {
compatible = "IONIKCLOUDHUB", "ralink,rt5350-soc";
model = "i.onik Wi-Fi Cloud Hub";

Pretty easy, define the product name and compatible platform, include some ready-made devices inside rt5350.dtsi.

gpio-leds {
compatible = "gpio-leds";

status {
label = "ionikcloudhub:red:status";
gpios = <&gpio0 9 1>;

gpio-keys-polled {
compatible = "gpio-keys-polled";
#address-cells = <1>;
#size-cells = <0>;
poll-interval = <20>;

power {
label = "power";
gpios = <&gpio0 0 1>;
linux,code = <0x116>;

reset {
label = "reset";
gpios = <&gpio0 10 1>;
linux,code = <0x198>;

My attempt at specifying the GPIO devices.

&spi0 {
status = "okay";

en25q64@0 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "jedec,spi-nor";
reg = <0>;
linux,modalias = "m25p80", "en25q64";
spi-max-frequency = <10000000>;

partition@0 {
label = "u-boot";
reg = <0x0 0x30000>;

partition@30000 {
label = "u-boot-env";
reg = <0x30000 0x10000>;

factory: partition@40000 {
label = "factory";
reg = <0x40000 0x10000>;

partition@50000 {
label = "recover";
reg = <0x50000 0x1c0000>;

partition@210040 {
label = "firmware";
reg = <0x210000 0x5f0000>;

This is the most important part. It specifies the flash configuration, for example it tells that uBoot resides between addresses 0x0 and 0x30000. I don't know if this is correct, but it works for me. The important bit is the "firmware" partition at the end. Everything else was mostly guesswork and might be wrong. But it works.

&pinctrl {
state_default: pinctrl0 {
gpio {
ralink,group = "i2c", "jtag", "rgmii", "mdio", "uartf";
ralink,function = "gpio";

&ehci {
status = "okay";

&ohci {
status = "okay";

&wmac {
ralink,mtd-eeprom = <&factory 0>;

I have no idea what anything above does. But every other device seems to have them, so I added them in. EHCI and OHCI refer to USB ports, as far as I can tell.

Building the custom firmware

After making sure all the files above are modified/added, you just need to type "make menuconfig".
Then go wild adding options to your ROM. You will quickly run out of flash space.

An option marked as 'm' means module. The option is compiled but not included inside the image. Rather, you can add it later to your device, temporarily, via a USB stick or similar. It might trigger (on) some other features which will eat precious Flash space. So just add only what you need, check the size of the image, repeat.

To build run "make -j4". This builds the firmware using 4 threads. If anything fails, you will have to build single-threaded and with verbose mode one. Refer to the documentation.

The resulting image will be in the bin/rampis folder:

adminuser@virtualboximagescom-VirtualBox-14:~/openwrt/bin/ramips$ ls -l
total 46132
-rw-r--r--  1       740 Jan 20 16:45 md5sums
-rw-r--r--  1  5812101 Jan 20 16:45 openwrt-ramips-rt305x-ionik-cloud-hub-initramfs-uImage.bin
-rw-r--r--  1 6291460 Jan 20 16:45 openwrt-ramips-rt305x-ionik-cloud-hub-squashfs-sysupgrade.bin
-rw-r--r--  1 5111808 Jan 20 16:45 openwrt-ramips-rt305x-root.squashfs
-rw-r--r--  1 1129526 Jan 20 16:45 openwrt-ramips-rt305x-uImage.bin
-rw-r--r--  1  5810315 Jan 20 16:45 openwrt-ramips-rt305x-uImage-initramfs.bin
-rwxr-xr-x  1 3452468 Jan 20 16:45 openwrt-ramips-rt305x-vmlinux.bin
-rwxr-xr-x  1 3457480 Jan 20 16:45 openwrt-ramips-rt305x-vmlinux.elf
-rwxr-xr-x  1 8071108 Jan 20 16:45 openwrt-ramips-rt305x-vmlinux-initramfs.bin
-rwxr-xr-x  1 8076120 Jan 20 16:45 openwrt-ramips-rt305x-vmlinux-initramfs.elf
drwxr-xr-x 10     4096 Jan 11 22:36 packages
-rw-r--r--  1 1140 Jan 20 16:45 sha256sums

The uImage-initramfs file is the one you need to be looking at. It has to stay under 0x5F0000 bytes (6,225,920 bytes for those stuck in decimal).
But it should not get close to that value, as the remainder of the space is used by OpenWRT to keep user configuration. I recommend to stay under 6,100,000 bytes.
If your image exceeds that size you need to run 'make menuconfig' and play with the options until you get it to fit.

Flashing your first image

If inside the normal (factory) firmware:

# mtd_write write /media/sda1/mtdblock5 Kernel
Unlocking Kernel ...
The system is going down NOW!lock5 to Kernel ...  [w]
Sending SIGTERM to all processes
Requesting system reboot
Restarting system.

Replace the mtdblock5 file with the *squashfs-sysupgrade.bin from above.

Inside the failsafe firmware you can run this:

# mtd_write -r write /media/sda1/openwrt-ramips-rt305x-ionik-cloud-hub-squashfs-sysupgrade.bin mtd5
Unlocking mtd5 ...
The system is goingRestarting to mtd5 ...  [w]

I don't remember the details right now, the above might be reversed, but you can play around if you have a backup. Make sure you are writing to the correct partition and do not touch uBoot and minisystem.

If you mess up, you will have to use an SPI flasher to restore the flash contents. There are various tools and tutorials online, you could probably use a Raspberry PI or Arduino for this, but you would still have to solder the tiny wires or buy a SOIC-8 clip.

After the first OpenWRT image is flashed from the command line, and it works, subsequent images can be uploaded from the web interface.

Update - Pastebin link with the source changes


The build configuration files might be wrong.

Related to the above, the name of the device does not follow any convention. It might also require renaming to make an OpenWRT upgrade possible by uploading from the original firmware's web interface.

I haven't found a way to remove IPv6, it seems to be a bug in the OpenWRT build tools.

I don't know what I'm doing and this is not helped by the fact that I could not get any community support, at least not on the openwrt forums.

I will upload the configuration files and resulting firmware at some point in the near future, remind me of that if you need it before then.

Sunday, February 12, 2017

Designing a better diesel tuning box - part 5 - tweaks and updates

Living close to a densely populated area means that it's hard to do consistent testing without spending a lot of fuel, which is also expensive.

Nevertheless, I took the pen&paper approach and started working my way from the basics.

I studied all the Bosch sensors from this page, used a bit of common sense and figured out that my sensor is a Bosch 0281002691, or similar, with a 180 MPa (26000 psi) nominal rating. This might be wrong but It's a good place to start.

I've already used Torque and my multimeter to get some data and it seems to fit with the sensor I've chosen. It might be wrong, but so far it clicks into place.

Using the data I've gathered I've created a simple JS page that shows some logs and tries to simulate what my module (and sensor) does:,output
(Note that this is the HTML/JS result after I did the interpolation.)

So the basic function is: the ECU commands the pump, this delivers a pressure, my module receives the sensor data (voltage), offsets it, outputs a new voltage to the ECU, the ECU processes it. I missed a step the last time: the ECU will receive the adjusted pressure, output a new pressure, the pump delivers, a new pressure is measured. This can cause oscillations within the engine, as the tuning module attempts to adjust for the new value.

Thursday, February 2, 2017

Automated coffee machine troubleshooting chart

My old post on the Saeco Talea Giro machine teardown (including deprecated one) has had tremendous success and I frequently get questions on how to fix this or that.

I am no specialist on this stuff but I've managed to keep my unit running after it was used in an office environment (>50000 coffees). So for me it's mostly guesswork and some logic, but I'll display this so that you can help figure out the problem with your own unit. I'll try to make this accessible to non-technical people, let me know if some idioms are too advanced.

I will try to update this guide with usual questions, but this is not a replacement for professional servicing.

Before troubleshooting make sure that the unit is cleaned and descaled and has enough water. Use the manual for this, each unit is different. Also, try turn the unit off and on, perhaps leaving it 1h undisturbed. This works around some of the bugs in software (firmware).
Learn the sounds of the machine and try to understand what it does in its normal state. There are several motors and they are easy to identify by sound.

Refer to my original post (from years ago) if you want to understand more about how such a unit is constructed:

Wednesday, January 18, 2017

i.onik Cloud Hub

I bought one of these cheap 'wireless drives' from Amazon:

Currently (early 2017) selling for 15E, I think I paid 12E including shipping. This post will focus on basic features and some early data. Later posts will go into some reverse-engineering, featuring a great YouTuber, LiveOverFlow. If you like reverse-engineering you will surely enjoy his tutorials. By the time you read this he will have probably published his first video showing you how to get into the device.
He also discovered that a very similar device is being sold under the Strontium Mobile Wifi Cloud (Sri-CUBa-3KW) moniker in US and India. However that one is advertised as having a 3000mAh battery while this one only has a 1900mAh one.


The excelent video from LiveOverFlow is up:

Saturday, January 14, 2017

Quick note on Raspberry PI SDCARD reliability

I've been using a 4GB on an rPI "clone" - the Banana PI - and have been happy so far with everything the board has to offer, as a headless server. However, I started getting some errors after ~3 years of usage, with the card and at one point it stopped booting completely. Nice timing as well, it's not fun losing your music streaming server at Christmas time.

Long story short, the card has been used at 80-90% most of the time, which left very little space for wear leveling. I hooked it up to HDMI and could see a lot of error messages on the screen about mmc. So the card was dead and I feared the worst. last backup having been made a month prior to this.

Never fear, just writing imaging the card (Win32DiskImager) and copying the image to another 16GB card worked fine. So if you run into this it might be worth it to just try and duplicate the card to another one. In my case, no other changes were required.

Thursday, October 20, 2016

Recovering data from broken screen Android phone - alternative

I was tasked with the issue of getting contact data from a broken Android phone (in this case Xiaocai X9). The touchscreen was functioning erratically, the display was blank, adb/developer debug was not enabled.
I've tried for some time to enable debug by dragging randomly on the screen, making a screenshot (hold down volume key + power) and trying again but gave up after an hour or so.
So: broken touch, broken LCD, no adb.

Tuesday, August 23, 2016

Designing a better diesel tuning box - part 4 - improved design results

If you are following the project you might've seen that the new source code for the firmware and (Android) client application are up:

Arduino firmware:
Mobile UI:

With that out of the way, I've had about a month of testing with the new prototype and several months already with the old one. The definitive result is that there are significant fuel savings.

Outside city limits I now get better than 6L/100km, at highway speeds (130 km/h) better than 6.5/%. I believe the highway consumption can be further improved but I haven't used the car so much lately to be able to fine-tune the settings.

Previously I would get 7.6L/100km at best on country/county roads and 7.4/% on highways. So that would be a 12% mileage increase on highways and 21% on slower roads.

Inside the city is where the story changes since that's where I did most of my driving and had time to tune the parameters. I am now getting an average of 9L/100km (actually better) compared to 11L stock or 12.5L with RaceChip. So that's 18% mileage increase from stock and 28% increase from RaceChip..

Why such a difference?

The issue is a bit more complicated and I found it related to matching between sensor output impedance and ECU input impedance. That's why the improved prototype has provisions for adjusting this. On my car, with the default 'Arduino' circuit I need to set the offset correction to -50mV and gain correction to +3% in order to match the factory settings.
I doubt any of the aftermarket solutions account for this and is the reason why I get such poor city mileage with the commercial tuning unit.
The commercial units are likely ok at higher rpms since the gain correction is built-in (part of the tuning) and the offset error becomes insignificant.

The app

Building a mobile app was a great idea since it allows me to connect to the module, adjust the settings on-the-fly and save them.

I would probably redesign it now since I know now the usage pattern: adjust gain and offset once, play with the curve point gains indefinitely, save them. Currently the gain and offset are the biggest UI elements since the majority of the improvements can be achieved through those.

The 'Apply immediately' checkbox is also really useful as it allows the user to play with the values without having to hunt for the 'Apply' button. As soon as some settings are changed the application waits for a while (1-2s) and sends the new settings to the car.

It's cool showing the phone to someone and watch the consumption modify as you play with the values. A bit silly, but makes for a 'wow! never thought this would be possible' moment.

Adjusting the individual gains however is a bit tricky to do while driving (or stopped for that matter) since they are quite small and a lot of them.

I opted to add +/- buttons on the sides of each point setting instead of the classic numpad editor which is impossible to use at the wheel.

The app will also helpfully highlight the currently selected point (in blue) so you can see where the engine is at.

With the 'Apply immediately' feature it's just a matter of tapping '-' and wait 1-2s and see the effect.

Speaking of effect, the whole concept now seems a bit wrong to me - you are adjusting the END value not the START value so anything that you've adjusted affects where the next value will be. E.g. if you adjust the value for 200 (ADC = .244V) to lower it by 10% the ECU will compensate and now the new value will be 200+10%. I cannot explain this properly in words but I'm working on the EFFECT rather than the CAUSE.

Another interesting issue is that the engine does not run well at very low fuel rates, regardless of the setting. As long as the stationary consumption is above 0.7L/h the engine sounds fine, as soon is it goes below that it starts shaking. The 'solution' is to raise the consumption back by putting it in gear or starting A/C. So a 'cold engine' tuning should be different than a 'warm engine' one since consumption decreases as the engine warms up (emissions-related). At 0.4l/h the engine shakes badly.

Speaking of shaking, the automatic gear shift is not so smooth anymore since it's probably hand-tuned for specific torque values.

I haven't noticed any significant loss of power but I'm not the street racer type.


I'll probably stop working on this project for a while and deal with the other pending projects since I think the goal was achieved.

I would like to integrate real-time reading of OBD2 values: fuel rail pressure (PID 59?), engine RPM (PID 0C), oil temperature (PID 5C), fuel rate (5E) and vehicle speed (0D). This would allow better data logging and perhaps some auto-tuning, through the app.

Would be nice to have a separate control module with real buttons and knobs instead of a smartphone.

Would be nice to use the internal Arduino temperature sensor to select different curves or values depending on ambient (engine) temperature. It should be good enough for most purposes.

Would like to find out if there is any damage that can occur when setting an extremely low consumption. I'm using the engine sound (smooth, rough, shaking, ...) to tune the settings now but I don't actually know why it's behaving like that since the rail pressure is well within parameters.

Tuesday, August 2, 2016

Cost analysis of a Lexmark inkjet printer

Six years ago I bought a Lexmark Pro205 all-in-one printer, one of the few affordable ones that had WiFi. This has proven a disastrous investment, so let's go quickly through the numbers:

  • purchasing price (10 Mar 2011): 140 EUR
  • black cartridge replacement (21 May 2012): 12E
  • full ink refill set (21 Dec 2013): 18E
  • full cartridge replacement (25 Mar 2014): 13E
  • full cartridge replacement (12 Mar 2015): 12E
In total 195E, there might be other expenses as well.
Electricity costs are not included and the printer is not very economical in standby.

Printed pages - as per printer counter - 691. I would estimate the total number of usable pages to be ~200, out of which ~15 were full-color photos. This is because most of the pages from beyond number 80 had streaks and the printer required at least 50 deep cleaning cycles. About one page in five is usable, but certainly not great.

So running costs until now are 1 EUR / page. That's definitely the most expensive printer I have owned.

In comparison, around 5 years ago I bought a Kyocera FS-1020D laser printer refurbished for 30 EUR. It has printed around 1000 pages with a discard rate of 1:50. That is, 1 in 50 pages came out bad because of the printer. So the running cost for this printer is <4 cents/page. No maintenance required other than the thermal fuse blowing out because it was sitting in an enclosed area (2h, see a recent article about fixing that).

Sunday, July 31, 2016

HackerX Frankfurt experience

This a departure from my normal subjects, but I don't have a blog dedicated to my software work.

I have recently attended the first HackerX instance in Frankfurt. For those who don't know, it's like a speed-dating event where potential employees and potential employers are face-to-face for 5 minutes, then the candidates (employees) rotate over to the next company.

Right off the bat I should mention that I did not receive my own invitation but I used one from a colleague. However the only difference is a missing email.

Tuesday, July 26, 2016

Blog updates July 2016

I was assuming that having some time off would allow me to update this blog more frequently but there is always something shinier.

Diesel Tuning Box (for lack of a better name)
I've tested extensively the latest iteration that does semi-automatic calibration and found no issues with the circuit itself. However there were many issues with the ghetto-style DB15 connector made using hot glue. Once I got the proper connector in it will stay in the car at all times.

The issue was caused by raised temperatures under the hood deforming the hot glue and leaving just a tiny contact patch that allowed very little current to flow in. Anything over 20mA would break the contact yielding 'check engine' errors. If you are fast, the errors go away when restarting the engine. If you are slow (>2 minutes) you need to reset the error using an OBD2 diagnosis kit. I used a bluetooth OBD2 connector (~12$) with the Android app Torque, while driving.
I'm testing these limits so you don't have to.

Otherwise, with the new software it has proven reliable enough and allows for realtime (while driving) control of tuning. However the serial interface has proven prone to error - while trying to insert comments in the log files my co-pilot inadvertently altered some settings. This will be improved by writing a phone app that will allow adjustment on the fly and saving of the log files. Currently still in the process of getting up-to-date with Angular2 and Ionic2, but I already have a working app. The source code - once final - will be published on my github page.

Printer repair
While doing the taxes my Kyocera FS-1020D laser printer died with a strange blinking error: the first three LEDs blinked slowly, then just the second LED blinked. After a bit of service manual hunting I found out this was error 6000 - fuser unit error.
It took a bit over an hour (including pictures) to work around the problem: the thermal cutoff  (fuse) was triggered which left the fuser lamp without power. I just soldered a wire between the fuse contacts since the printer already has a thermistor in place for monitoring and cutoff. Not 100% safe but I doubt it will start a fire. The fuse was rated for 157C, will write a detailed post once I find the time.

Odys Winpad V10
After an uneventful Windows 10 upgrade the tablet has been running fine with no significant drawbacks compared to Windows 8. To get the most battery life and keep the tablet cool I suggest setting the wireless connection to metered: this will stop the automatic updates and maintenance.
I also cut the cord from the power supply and attached a standard USB male connector to the tablet end and a female connector to the other end. This allows me to charge it using any USB supply.
Battery life is between 6h under moderate load (frontend development) and 12h idle (while connected to HDMI). To get the most of the battery I recommend turning on airplane mode whenever WiFi is not needed.

I scanned the steel paperweight inside the keyboard (230g) and looking for a way to replace it with some 1-2mm aluminium sheet. The new backplate would then be less than 75g, but some counterweights (~30g) might be needed to keep it from toppling over.

I have replaced/removed/re-soldered some caps inside the keyboard that made an annoying whine (5-15kHz). Just look for the biggest ceramic capacitors there and either resolder them to be less rigid or replace them with something of improved quality.
I have tried every other possible solution: using a strong glue to dampen them, changing orientation, adding some padding material - nothing except the above worked.

CTC 3D Printer
A gen 1 Raspberry PI was setup up as a remote web interface using OctoPrint. However there are many issues with it that prevent me from slicing files remotely (including the rPI speed). It also requires an OctoPrint restart whenever a job is cancelled, so it's far from ideal.
I installed the SailFish firmware on the printer and it has proven a huge benefit: the temperatures and speeds can be altered in realtime, allowing for example to print the first few layers slowly and the middle ones twice as fast.
I have been unable to use Simplify3D on it, currently MakerBot seems the best option.

Li-Po powered compressor
For my bikes I have to check the tires pressure quite often and this poses several problems: I don't have a nice high-pressure pump, it takes quite a while to bring racing tires up to pressure (8 bar) and it also takes a lot of energy. So I made a connector that has on one end alligator clips and a female XT90 connector and on the other end a 12V automotive (female) socket, the ones used for cigarette lights. With a cheap (15EUR) compressor I can now check and adjust the pressures in just a few seconds and can use either a 3S LiPo battery or a small motorcycle (or UPS) 12V battery.

Monday, May 23, 2016

Designing a better diesel tuning box - part 3 - simplified design results

As I wrote in the previous article, the barebones design has been through some basic testing - 500km mixed environment driving - and has been mostly successful so far.

I had a suspicion that the output impedance of the circuit must somehow match a known impedance, but was not sure which. The clue was that the RaceChip unit raised city consumption by 5-15% even though it had no effect during the bench testing.

Here's a datasheet for a similar Bosch pressure sensor:;jsessionid=A20738712FCFB9E51CA919DD7D2F9E91.sundoro2?ccat_id=275&prod_id=516

For testing they are using a pull-up resistor, so on the input side of the ADC the same circuit must be simulated in order to drive the sensor. I used a 10k resistor, but perhaps even the internal pull-up could work.

At the DAC/PWM output I found out that a 1.5k resistor was too large and could not sink the ECU input line low enough. With a 10ohm resistor it seemed to work fine, perhaps 47ohm would also be ok. I don't have a definitive value yet as I want to implement it in another way.

The initial barebones circuit used an Arduino Nano (v2?) without RTS/CTS lines on the serial port. This means that on startup, the bootloader takes around 2 seconds until it jumps to the main loop. The car does a basic check and reports the sensor as faulty. The solution: turn the ignition off and immediately back on, before starting the engine. This is because there is a 30s delay from ignition off until the systems are powered down, at least on my car. It's also a nice anti-theft measure, the thief can only drive with reduced power, I think around 20%.


Idle consumption with my unit is now at 0.5l/h when warm, compared to 0.8-0.9L/h stock, 0.9-1.1L/h with RaceChip. So >30% fuel savings while idle.
The idle is a little shaky if unloaded, runs smooth if some load is added (A/C or in drive gear). Incidentally, with the unit disabled but in-circuit, the behavior is almost the same (0.6L/h) which means the input/output impedance is mismatched.

Highway consumption yielded a 5.7L/100km average on one trip, and then 6.3l for the return trip, so I would say a 6L/100km is achievable. Stock was around 8L, with RaceChip around 7L. I think that's pretty impressive, 25% highway mileage increase - see updates at the end of the post.

Here are the settings used during the test drive:


Torque is lower, but still adequate for day-to-day driving. I measured a stock 0-100km/h time of 8s, I would guesstimate now it's 10-12s. The car had no issues reaching 170km/h so there was no reason to do more tests, for now. My goal is improved mileage, a target of 1300km with one tank.

Findings and improvements

As I wrote above, the input/output impedance is really sensitive and there is no way to get a precise setting for each car. So my next step would be to design another simplified circuit with a relay. The relay would initially pass the sensor line to the ECU while de-energized, and use the Arduino 'passthrough' if energized.
During the calibration phase the Arduino would sample the input at the relay while it's off. When turning on, it will check if the input is the same through it's own circuit; if not, it will calibrate the input. It will then measure its own output and compare it to the input, when no modifications are applied. It will then save the output calibration constant.
Either way, there should be at least two trimmer pots or perhaps digital  pots, 1-15k for the input pull-up and 10-100ohms for the output. Of course the RC constant of the output filter is also affected by this.


There was an error in the Arduino playground EEPROM snippet, it reads a byte (0-255) and compares it with a char (-128 to 127) which fails the verification on values larger than 127.
I found the need of storing several curves inside the EEPROM, perhaps number 1 should be the default and have another 5 or so for testing (focused on power, consumption, city, highway etc).

The curve size of 10 points is a bit too coarse, perhaps I will increase it to 20 points.

Source code still at:


I've used a plastic food container to house the circuit. The plug was molded with hot glue as I cannot find any DB25 in my parts bin and still cannot source the original connectors. Bluetooth reception from inside the car is ok.

The small circuit board provides the input pullup, RC output filter and a way to probe and connect signals. I had to change its layout and components many times, which is why it looks like it has survived a war.

Update December 2016

In September I've had some problems with the DPF which caused me to initially suspect the custom module. However it turned out to be just a bad sensor that had to be replaced.
At that time I also took careful measurements of the consumption and found out that the OBC display was erroneous - the actual consumption was higher than reported.

I was worried that the increased consumption could flood the DPF causing costly repairs with seemingly no added benefit. However, I took the car to a dealer to have the real DPF soot measured and it was within nominal parameters (i.e. <6 grams).

I've since removed the module from the car but haven't done a lot of driving so without a definitive consumption baseline it's hard to tout any benefits. So far, stock, I'm getting 9L/100km in mixed driving and 12-15L in heavy traffic. I will need to do more precise measurements when refueling to see if that is a real value. If that is indeed a real value then the saving of the module is probably not 25% but still could be above 10%.

I need to see if I can access some real fuel flow data through OBD instead of the one derived by the OBC (which probably uses the rail pressure in addition to the flow meter).

TL;DR: the OBC display is way off sometimes and I cannot confirm any measurements. No negative side-effects have been observed.

Thursday, May 5, 2016

Designing a better diesel tuning box - part 2 - simplified design

There are many variables needed to get a reliable product, so while taking a break from the ISO automotive requirements I thought of playing with a barebones design - just an Arduino, an HC-05 module and perhaps a few passives.

Concept - this is similar to what the boxes on the market do - read the value on ADC, output the modified value with PWM. I'm using an Arduino Nano for this, took about half a day including the 'preview' spreadsheet.

Nano pinout:

  • Vcc to sensor supply (5V), from ECU
  • GND to sensor ground
  • A0 the output from the sensor
  • Pin 9 goes to ECU (former sensor data)
  • TX goes to RX of HC05
  • RX goes to TX of HC05
A0 should probably be pulled up to Vcc through a 1k resistor, I haven't tested this yet. Perhaps the Arduino weak pull-up would work.
Pin 9 (PWM output) should go through a resistor and capacitor connected to ground, 1k with 0.3u looks good in my tests.

The first two pictures show the Android phone connected to the HC05 for sending commands and receiving telemetry. The third one is the Arduino terminal on the computer running at the same time. While HC05 is serial data can be sent to the computer but not from the computer.

The user settings can be stored in the internal EEPROM.

After proving that the concept works and is fairly reliable (in a non-automotive environment) I took the time to make an Excel sheet (actually, OpenOffice) to chart the input versus output and compose the serial configuration string.

Regarding serial, the arduino sends each second a status with raw input and raw output. This incidentally also blinks the white LED (on pin 13) so you should see a bright flash if everything is running fine.

A tighter loop - every 10ms - reads the analog input and adjusts the PWM output. By default the output is sent unmodified (i.e. module is inactive), to get it to enable you need to send 'e' via the terminal. Conversely, send 'd' to disable it. While enabled, the LED will light up with a low duty cycle.

Terminal commands:
  • e - enable offset ('boost' car)
  • d - disable offset (do nothing)
  • rm - reads the minimum value from which the module starts working
  • rM - reads the maximum range
  • rc - outputs the entire configuration (version, min, max, curve points)
  • sm - sets the minimum range. Example: input sm300 - press enter
  • sM - sets the maximum range. Example: sM800
  • sC - sets a point on the curve. E.g. sC5117 sets point five to value 117. This means that during that specific range the output will be offset above by 17%
  • sX - sets the entire configuration in a single string. Can be generated by the spreadsheet
  • S - saves the config to EEPROM
  • L - loads the config from EEPROM, overwriting the current one
I won't provide a detailed explanation on how this works, just play with the green numbers in the spreadsheet to see how the output (blue) changes and whats the 'gain' (red) compared to original.

There is no error checking, no failed user input protection, no electrical protection, no watchdog protection and absolutely no warranty.

Other things: the PWM output is running at 60kHz, I think since the original sensor has a 2ms response time this could go unfiltered to the ECU. I assume they are filtering it there. The bootloader adds a startup time, ~5s, that could cause the ECU to trigger an error if it expects something during that time. I don't think it does.

To get you started, the minimum signal (while powered) should be 0.5V, the absolute maximum should be 4.5V, the car idle voltage should be around 1.2-1.5V. In my example above, the idle voltage is increased (to lower fuel consumption while idle) while during the other active ranges the voltage is decreased (adding power).

Power consumption is 25-50mA.

Edit: initial live tests

I got the engine light on (blinking coil) but the engine did start. The values I was expecting were a bit different than the real ones. Got an ADC value of 243 (1.18V) for engine idle (~780 rpm) and 256 (1.25V) for 1000 rpm.
It seems that the bootloader startup delay might be interfering with the ECU expectations (see above) or a pull-up resistor is required somewhere. Will have to do some measurements to determine the exact cause.

Monday, May 2, 2016

Designing a better diesel tuning box - part 1 - I/O board

As seen from my previous post and the sources enumerated in it there are several competing designs on the market that basically achieve the same thing - apply a negative offset to the rail sensor voltage.

Since none of them offer a desirable amount of control (for the price) I'm open sourcing an own design.


  • full programmability - curves, upper and lower threshold limits
  • telemetry
  • reasonably fail-safe
  • MCU agnostic - as far as possible
  • preserve the original waveform signal
  • easy to make - should not require exotic or expensive components

The overall architecture is simple: read sensor data into the microcontroller, process the signal, send an analog (PWM) signal out.

Disclaimer: this is probably not road-legal in many countries (missing certifications) and it might break the car subject. I am not responsible if anything bad happens, do it at your own risk.

However, it's not all dark, as I've already written there should be no damage as the unit still functions within factory settings and I will try to make everything as safe as possible.

In this first part I will focus on the driver electronics: concept, simulation, schematic and (perhaps) PCB. Since this is just a prototype I'm currently omitting protection circuitry.


The improved concept I came up with is applying the negative offset through an opamp subtractor. This way, if the microcontroller ceases to function the unmodified signal will be sent back to the car ECU.

The simulation above provides proof of concept: the yellow trace is the output from the pressure sensor, the blue trace is our modified signal that gets sent to the ECU.

Saturday, April 30, 2016

Racechip tuning box - part 2 - reverse engineering

See my first article for a short review and teardown:

First off let me start by saying I consider this fair use, as the instructions and website do not explain what the settings do, how the unit actually functions and what effects it can have. The description below refers to a single-channel Diesel engine (single common rail).


First off, most of the users will just want the simple explanations, here's a graph that should be in the manual:

The chart above shows 4 possible settings and their effects.
The first rotary encoder controls how much 'extra power' is requested. See 9E vs. BE vs. 4E
The second rotary encoder controls the RPM high range (endpoint). See BE vs B7.
The encoders go from 8 (minimum) through 9, A, B, C, ..., F, 0, 1 ... 7 (maximum).

Tuesday, April 26, 2016

Ricoh GR sensor dust cleanup

I bought a cheaper-than-usual Ricoh / Pentax GR APS-C camera on ebay that had a few minor issues.

One of the most visible ones was dust on the sensor, so I will show you two methods that I've used to clean it up - the hard way first, followed by the easy way.

First, to get the position of the dust spots a shot was taken with F/16 against a white background. The exposure was manually set to be as high as possible (while still retaining information), pre-focus was set to the closest position (macro).

The resulting image was then adjusted in Irfanview (Auto adjust colors) to get the highest contrast.

F/16, 1/3s, MF to closest position


You need a very clean room, no dust, have a dust spray available and preferably wear gloves to avoid getting fingerprints.
All parts that cannot be cleaned after assembly (LCD cover backside, LCD, sensor) should be placed facing down on some lint-free material.
While removing the screws take note of their length, color and thread style.

The hard way - removing the sensor

Removing the back cover

First you need to remove the large rubber hand grip. Start from a corner and slowly peel it away, trying not to stretch it. Do not remove the two screws visible below, near the lens, it's not required.

Wednesday, April 6, 2016

Odys Winpad V10

In search of a cheap and light notebook that I can use it for light tasks - such as Udacity courses and connecting lab equipment - I stumbled upon Odys Winpad V10 on offer at Amazon.
While the Lenovo Miix 830 seemed like a good deal at the moment it suffers from poor battery life, limited USB connectivity while charging and lack of keyboard+touchpad. Most Bluetooth keyboard with trackpad on market now have issues and are overpriced, so the Odys seems like a good fit.

This is a short review followed by a look inside the 'docking' unit.

Initial impressions

The unit is very heavy for its size, ~670g for the tablet and ~670g for the keyboard. The keyboard/touchpad base does not contain any other batteries or peripherals.

Battery life is pretty good, I got >6h for light work and the battery bar estimated >14h while idle and connected to the HDMI output with the tablet screen off.

The built-in touchpad is pretty bad - the bottom touch area is reserved by the left and right mouse buttons. Internally, they are triggered by a single switch ('clickpad') so the unit knows whether the left or right button is pressed by the touch position. Two-finger scrolling is a fixed feature and cannot be disabled or modified - the scroll direction is 'wrong', i.e. the Mac way.

The keyboard has good feedback, the keys have little sideplay and touch-typing is pretty comfortable. The layout is almost standard (Macbook-based), with the arrow keys controlling Home/End/PgUp/PgDown using the Fn modifier. No backlight unfortunately.

Sound is abysmal, the speakers are tinny and directed towards the back. The bass response can be improved with the free APO Equalizer and the latter issue can be worked around by cupping your hand on the side of the unit so the sound is 'redirected' towards you.

The 10" IPS screen has a good color reproduction and viewing angles. I've ran a 3-hour calibration procedure using an i1 Pro calibrator under dispCalGui and there were no discernible corrections.
At the minimum brightness the screen is too bright for night use so I use f.lux to work around that.

WiFi connectivity is spotty, but works decent enough (54MBps max.) when no USB is attached. However, when a USB mouse or other peripheral is used on the OTG port the WiFi drops out every couple of minutes for a few seconds. This is consistent and I haven't found a way around it.

The overall build quality is pretty good, there's no flex to any parts of the unit. Not surprising, given that the tablet part has a solid piece of glass and the base part is a solid piece of metal.

The charger (5V, 2.5A) is small, has a 90-degree plug with a standard connector. I haven't measured the time it takes to charge from empty to full but should be around 5 hours with no use.

The aspect is pretty utilitarian and old, reminding of the first-gen Atom notebooks (eeePC) with a fingerprint-happy grippy texture. The hinge requires a great amount of force to fold, impossible to do one-handed.

Performance is the same as expected with Atom Z3735F units with 2GB of RAM. I haven't upgraded to Windows 10 and don't intend to. Suffice to say that it seems to run fine for basic office tasks and the occasional light games. Frontend web development (nodejs, Chrome dev tools) run decently.


I did not bother taking apart the tablet unit as I assume it would be identical to the Miix 3 teardown I did earlier since it has the same hardware. At 670g the tablet unit has a better screen-to-weight ratio than the Lenovo and seems to provide a better battery life.

The base comes apart by removing the 4 visible screws plus another 4 screws hidden beneath the rubber feet.

The sheet metal backplate can be removed by messing with the 8 screws, 4 of which are located near the hinge.

The base [hinge] is connected to the tablet through some magnetic stubs and 5 pogo-pins.

I initially thought the pins are just a USB-passthrough but I now assume it's just an SPI extension port, with 3.3V power and signaling.

The base plate is surprisingly thick and heavy but serves several purposes: flex-free keyboard input, rigidity for the base when the 'laptop' is opened and transferring the load of the hinge to a larger surface area.

The rest of the base has a matrix-driven keyboard and the SPI(?)-driven touchpad going to one black blob.

The lower-left side has another metal plate, probably for adding weight so the laptop does not tip over so easily.

The lower-right side hides a magnet that signals the tablet unit when the clamshell is opened or closed.

Surprisingly, the keyboard has an additional backing metal plate:

At this point I've tried removing the thick sheet metal and found the unit was happy to work like this, except the touchpad. I was also worried that the keyboard might crack when opening the clamshell. However this brought the weight down to 1100g.

A close-up of the touchpad with a ruler, the two points would need to be connected with some other kind of plate in order to get the clickpad working again. For normal operation the touchpad can work with only touch input, so it's not really required.

The chip driving the touch input is a Cypress CY8CTMA140-LQI 2-finger capacitive sensing solution. It can function as an SPI or I2C slave but I assume it's used in SPI mode.
I don't have access to the full datasheet but it seems to provide the HID output while taking into consideration the clickpad button, so probably a reference design.
Unfortunately it cannot be configured (yet) in the way that Synaptics touchpads are.

By the way, the tension of the hinge can probably be adjusted by untwisting of the self-locking nuts located at the ends of the rotating rod.
However, you should find a way to lock them in place (Loctite) since the parts will eventually wear out.

Edit Feb 2017: I had made several changes to this unit

  • reduce weight of unit by dremeling(?) off parts of the keyboard backplate
  • reduce electrical noise of the keyboard dock (5-15kHz) by replacing or resoldering ceramic some capacitors
  • disabled W10 services like Defender, Telemetry, auto-update to improve responsiveness
  • used f.lux to decrease brightness at night
  • burned out the USB port with an Arduino - turns out the port is not protected, but there should be an extra one on the dock connector