Sunday 13 September 2015

Hacking an electronic price display, success!!

Somehow I found one of this tags (don't ask) and decided to hack it. The display is WF021-01 and you can find eink's datasheet here. Unfortunately this doc it in incomplete and it doesn't show the list of commands to control the display. Luckily I found many similar datasheets from other similar eink displays and noticed that many of those commands are the same across devices. I tried some of those commands and found the ones that work with my display. Tadaaa!

This is how the back of the device looks like:

I cant tell much about the epoxy blob, luckily the PCB has a bunch test pads that can be used to drive the display (I had to cut the traces to stop the main processor from interfering with my data):

This is what each test pad is for:

  • tp11: bs1(set this oen to ground so you can use the 3 wire interface a)
  • tp10: res
  • tp8 : d/c  (no need to drive this one if you set tp11 to ground)
  • tp7: busy
  • tp6: cs
  • tp5: d0
  • tp4: d1
  • tp1: vddi
  • tp18: gnd 

I am using an arduino to talk to the eink display, I'll post the code to drive it as soon as I clean it up a bit. Enjoy!