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Driving the Motorola F3 e-paper display

The Motorola F3/MOTOFONE was the first (and still is the only?) mobile phone with an e-paper display. Although this is not a pixel-based display, like found in eBook-readers (e.g. the Amazon Kindle or the B&N nook), it is still quite nice for experimenting with low power microcontroller projects.

E-paper/bistable displays have the ability to sustain the display content even without the supply of power, so initial idea I had was to build something like a clock, only powering the display when updating it every minute.

The display

The display consists of 182 individually drivable segments, which form a row of six 14-segment characters, a row of six 8-segment characters, and many symbols used for user notification and the menu.

PCB with segments of the displayassembled display showing all segments
The PCB of the displayDisplay showing all segments

Display controller

As you can see from this picture, the used display controller is a Solomon Systech SSD1621. Unfortunately there is no public datasheet, so I had to sniff the (32 bit) SPI communication between the TI Locosto baseband processor and the display. The protocol turned out not to be very difficult, just some initialization, some commands for actually writing the display content, and a command to refresh the display with the just transmitted content.
The most time has been spent for actually finding out which bit was for which segment, since all segments are wired up at random to the segment outputs of the controller. This is not surprising though, given that you need a circuit path to each and every segment - “just get them wired already, we can handle the rest in software” seemed to be the motto :-)

Interfacing with the display

Normally, the baseband board and the display/keypad pcb are connected with a 32-pin connector (exact model unknown). Luckily there are pull-up resistors and capacitors for every needed signal, so I decided to solder some wires there, instead of directly to the connector. The schematics of this phone are floating around the web (just search for 'f3_schem.rar').

thin wires soldered to the display pcb the connector of the display

Discussion

satansitik, 2013/05/27 19:39

Hi Can You publish list of command to driving this display?

Steve M., 2013/06/13 10:40

I don't have a list, but take a look on the driver I wrote, there are some comments: https://github.com/steve-m/epaperclock/blob/master/src/display.c

Don, 2014/01/02 09:30

I am fascinated by this little phone. And I notice on amazon the many people have purchased peripherals for it, like power supplies and headphones, in the last year which makes me wonder if it is becoming popular. Anyway, the clock seems to lose a minute a day at least when in the 24hr mode. Do you have a fix or do you have a guess as to why? I greatly admire the detective work you've done. Your work is excellent.

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epaper_display.1297906615.txt.gz · Last modified: 2011/02/17 02:36 (external edit)