Hi,
my LPC1768 is taking the 32.768KHz external crystal as clock source and I can only access it via the JTAG interface.
I see I can debug the code by setting the lpc1768.cfg openocd config file with
jtag_khz 1
When I try to flash @ 1KHz, it looks like the target screws and the bootloader is started in ocd/gdb I get these type of messages:
keep_alive() was not invoked in the 1000ms timelimit. GDB alive packet not sent! (2310). Workaround: increase "set remotetimeout" in GDB
Of course, as the bootloader is started, I have the nice opportunity to switch the jtag_khz setting to 500 ( 4MHz/8 ) and flash the target back to a working clock config, but
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WHY does the target screws when I try to flash it @1KHz jtag speed?
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WHY is the bootloader started (it looks like something is actually screwed by the flash procedure).
Funny thing, this behavior is back again when I try to speed up the clock @100MHz: I can reprogram the board, and the code starts running @100MHz, then when I flash it again, the target screws and enter boot mode (4MHz). From there I can flash it again @100 MHz or lower clock rate (recovering the control).
Please let me know if you need flash procedure logs or other information! I’m very concerned about this behavior…
RM