2012-05-02 07:31 AM
Hi,
we are using three STM32F3210E-Eval for about 1 year now. Recently 2 of these boards stopped responding via JTAG. The JTAG interface used is a Segger J-Link Edu. Different J-Links on different PCs have not made a difference. The third board still works fine. The J-Link Commander from Segger gives the error message ''TDO is constantly high''. I have also tried lowering the JTAG frequency and using SWD instead. Nothing works.Any suggestions?Regards,Tobias2012-05-02 07:42 AM
Somethink like this ?
[DEAD LINK /public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/STM32Discovery/STM32F4DISCOVERY Cannot connect to the MCU device&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&TopicsView=https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/AllItems.aspx¤tviews=287]https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fSTM32Discovery%2fSTM32F4DISCOVERY%20%20%20Cannot%20connect%20to%20the%20MCU%20device&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&TopicsView=https%3A%2F%2Fmy.st.com%2Fpublic%2FSTe2ecommunities%2Fmcu%2FLists%2FSTM32Discovery%2FAllItems.aspx¤tviews=2872012-05-02 08:05 AM
It's frankly more probable you have code early in the reset path that alters the GPIO's used by JTAG/SWD, or DMA or WFI loop. A quick test would be to get the BOOT0 pin high so that it enters the System ROM at reset instead, this acts as a safe harbour from where you can erase and program the flash.
2012-05-03 05:40 AM
I tried before to erase the flash via the built-in bootloader. But that did not fix the problem. I will now hook up an osci and see, if the mcu really does not respond on the TDO pin.