stm32f407, jtag does not respond

[romaine]

Posted on January 02, 2013 at 23:09

Hi all,

I have a strange behaviour with 4 stm32f407 boards related to the jtag. The jtag of the stm32f4 is connected to a FTDI4232 chip. I have connected only the JTCK (with a 10k pd), the JTDI (with a 10k pu), the JTDO (with a 10k pu) and the JTMS (with a 10k pu). The NJTRST pin is reconfigured at the reset as the SPI MISO function. To program the FLASH I use an openocd script. Everything worked fine for month and suddenly, I cannot reprogram the FLASH. In my new software release, I use the instruction wfi (when the kernel runs the idle process) and I have reconfigured the GPIO pin handling the NJTRST. Time to time the programming process is operational, but this happens 1 every 10000 tentative :(

The programming operation is done with boot0 connected at 3.3V and boot1 fixed on the pcb at gnd.

What can I try for recovering again the control of my systems? The silicon revision is A.

Thank you for your advise.

Best regards

  Rom. #jtag #flash #stm32f407 #openocd

[Tesla DeLorean]

Posted on January 03, 2013 at 00:52

Do you have a good power-on-reset circuit, and can you clamp NRST/NRESET low on you programming header to get an effective and repeatable reset?

[romaine]

Posted on January 03, 2013 at 10:13

Hi Clive1,

Thank you for your suggestions. You put me on the tracks and I was able to figure out the problem. The pin NJTRST was float!! With the scope I discovered that the level was close to gnd. I have just pulled up properly the pin and everything work fine!

Thank you again for your help,

Regards

  Rom