Jolla and SailfishOS

The Other Half EEPROM programming using an Arduino Uno as In-System-Programmer

2016-08-23 09:37

Experiment

It's time to bring out the hardware!

Programming

The setup is like shown in Fig. 1. Don't mind the differences in the EEPROM size or the resistor values. That should not make a difference.

We:

1. progam the ISP code into the Arduino, using e.g. the Arduino IDE
2. connect to the Arduino using e.g. Hyperterminal (9600baud, 8N1)
3. wait a second in awe...

If we got it right, the result should look like this:

Reading from Jolla Phone A

If we did a good job, this EEPROM now should be readable for the Jolla A TOH-demon.

Let's hook up TinkerTOH-2, to see what we get.

If you take closer look at the picture, you'll see the implementation of this circuit:

• The SCL and SDA ports are connected to the Jolla A Phone using TinkerTOH-2.

• Since these ports are 1.8V we have to use a level shifter circuit, if we want to connect e.g. 3.3V or 5V electronics.

  I just had Adafruit's "4-channel I2C-safe Bi-directional Logic Level Converter - BSS138" around (the blue board under the SDA/SCL flags on the left).
  But it is easy to build your own, e.g. by using a couple of BSS138 N-Channel Enhancement MOSFETS.

• The 3.3V power supply for the high voltage side also is provided by the Jolla phone via TinkerTOH-2.

• To generate the low voltage 1.8V supply I used the MCP1700 LDO (small green board on the right side).

Let's see what the Jolla makes of the EEPROM content.

• Open a terminal on your Jolla phone.
• devel-su
• cd /sys/devices/platform/
• Clip-On TOH to make toh-demon read the EEPROM.
• ll and cat the files in cd /sys/devices/platform/ should show a result like this:

  

Looks good to me!

Now have a look at https://wiki.merproject.org/wiki/The_other_half to see what you can do with it.