[ell-i-developers] OpenOCD and ellduino

  • From: "Atte Peltomaki" <atte.peltomaki@xxxxxx>
  • To: ell-i-developers@xxxxxxxxxxxxx
  • Date: Fri, 6 Jun 2014 17:07:17 +0300

Hi hackers,

I have one ELL-i dev board and a Sparkfun Basic USB<->RS232 converter
with FT232R chip. I've been trying to get it to work with OpenOCD,
namely flashing and sending halt/reset commands to the board.

OpenOCD doesn't have support for flashing with serial commands, which is
what stm32flash does. I don't think this is terribly interesting anyway.

OpenOCD also lacks support for FT232R, which would be more interesting.
My idea is to connect the Sparkfun adapter to the ARM SWD pins, present
on ELL-i board as PA14 (SWCLK/TCK) and PA13 (SWDAT/TMS). There's already
basic SWD support in OpenOCD, remaining work would be adding support for
FT232R synchronous bit-banging mode and glue it to talk SWD.

A patch for adding FT232R support is floating around, though this only
adds support for JTAG and not SWD. Adapting the patch for SWD is
currently work ongoing.

Let me know if you have comments, eg. if I'm trying something
stupid/impossible. A lot of this is completely new to me, so please bear
with me :)

...

References:

FT232R patch:
http://vak.ru/doku.php/proj/bitbang/bitbang-jtag

FT232R bit-banging mode docs:
http://www.ftdichip.com/Support/Documents/AppNotes/AN_232R-01_Bit_Bang_Mode_Available_For_FT232R_and_Ft245R.pdf

SWD documentation:
http://mobile.arm.com/files/pdf/Serial_Wire_Debug.pdf
http://www.pjrc.com/arm/pdf/doc/ARM_debug.pdf

ELL-i board pin layout:
https://github.com/Ell-i/Hackathon/wiki/Ellduino%20expansion%20headers
http://arduino.cc/en/uploads/Main/ArduinoADK_R3_Front.jpg

Sparkfun Basic schematic:
https://www.sparkfun.com/datasheets/DevTools/Arduino/FTDI%20Basic-v21-5V.pdf

-- 
Atte Peltomäki
     atte.peltomaki@xxxxxx <> http://kameli.org
"Your effort to remain what you are is what limits you"

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