On an earier post in the repair a damaged headunit topic, Totalfree was so kind to reveal the JTAG pinout of the MMI 3G unit.
Pinout side connector, front of unit facing left:
U1............U10
===========
B1............B10
Board connector FT2232 jtag interface
U6= MPMD -> attach to 3.3V+
U7 = TDI -> TDI
U9 = TRST -> Attach to PRESET (B7) - to TRST
U10 = TCK -> TCK
B7 = PRESET -> Attach to TRST (U9) - to TRST
B8 = TMS -> TMS
B9 = TDO -> TDO
B10 = GND -> GND
I have hooked up the unit to a FT2232 JTAG interface according to the scheme above (with trial and error i created the above scheme).
When the unit is powered up TRST (interface) must be connected to ground, in comination with MPMD high the jtag interface becomes active.
When scanning the JTAG chain there is a device answering (so communication over JTAG possible ).
Next thing is to figure out how the flash is connected to the SH7785 by using a bsdl file from reneseas.
Result so far:
UrJTAG 0.10 #1502
Copyright (C) 2002, 2003 ETC s.r.o.
Copyright (C) 2007, 2008, 2009 Kolja Waschk and the respective authors
UrJTAG is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
There is absolutely no warranty for UrJTAG.
WARNING: UrJTAG may damage your hardware!
Type "quit" to exit, "help" for help.
jtag> cable ft2232 vid=0403 pid=8A98
Connected to libftd2xx driver.
jtag> detect
IR length: 8
Chain length: 1
Device Id: 00001000000000011111010001000111 (0x000000000801F447)
Unknown manufacturer!
chain.c(149) Part 0 without active instruction
chain.c(200) Part 0 without active instruction
chain.c(149) Part 0 without active instruction
jtag>
Question did anyone have a succesfull JTAG session with the MMI unit, or has some comment or tips?.