Hi all,
I'm using OpenOCD (version 0.4.0, downloaded from SourceForge and built
about half an hour ago) on Debian Lenny (5.0, stable) running under
VMWare Fusion on an x86 Mac Pro. The microcontroller I'm using is an
STM32F103C6T6, and the JTAG dongle is an Amontec JTAGKey. By and large
it works: I can program the flash, halt, use gdb, all the things I'd
expect from OpenOCD.
But there's a way of breaking it semi-permanently. The application on
the STM32 is one which spends most of its time with the CPU in Stop
mode, waking up periodically (about every 12ms) via an RTC interrupt to
do some processing. If I attempt to start OpenOCD while the
microcontroller is stopping and running like this, I get messages which say,
Warn : Timeout (1000ms) waiting for ACK=OK/FAULT in JTAG-DP transaction
and OpenOCD just won't work, though it finds the TAPs correctly so the
JTAG hardware is clearly working to some extent.
The whole JTAG system appears to be then stuck in this state. Restarting
OpenOCD, doing a hardware system reset on the microcontroller,
unplugging everything including the JTAG dongle and its USB interface,
all make no difference. I've even tried exercising the JTAG port using
another application (XJTAG) though this only does boundary scan testing
and doesn't play with the ARM debug TAP. Though boundary scan works fine.
The only thing which fixes the problem is power-cycling the STM32 chip
itself. I note from its documentation and the ARM Cortex-M3 TRM that
some parts of the core debug unit are only reset at power up, not in
response to a system reset. The device has no TRST pin.
However, this board is going to be permanently moulded into a plastic
lump with a battery, so power cycling it is *not* an option.
Am I stuck? Or is there a way of finding out how the Cortex-M3 debug
unit is wedged, if that's the case, and tickling it back to life?
Thank you
Chris
--
Chris Jones - ch...@martin-jones.com
Martin-Jones Technology Ltd
148 Catharine Street, Cambridge, CB1 3AR, UK
Phone +44 (0) 1223 655611 Fax +44 (0) 870 112 3908
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