STM32 newbie question

cxu_dl · ‎2012-08-24

Posted on August 24, 2012 at 09:27

Hi ,

I'm new to STM32. Just designed a new board and assembled a prototype, but it does not work. when I connect J-link to it through SWD (three wires) interface, and start debugging, uVision4 gives these warnings:

========================================================

**JLink Warning: RESET (pin 15) high, but should be low. Please check target hardware.

***JLink Error: Supply voltage too low (1 Volt is required, Measured: 0.0 Volt).

Please check target power.

=====================================================

then a dialog pop up with the message ''No Cortex-M SW Device Found''.

My device is STM32F100C8T6. I measured voltages at the three VDD pins (pins 24,36, 48), they are 3.3V, as expected, VBAT(pin 1) and VDDA(pin 9) are connected to VDD as well.

The way I connected SWD to Jlink is: Gnd to pin1 on Jlink 20-pin connector, pin 37(SWCLK) connects to pin 9 on Jlink 20-pin connector, and pin 34(SWDIO) connects to pin 7 on Jlink 20-pin connector. This configuration works for the STM32 dev board I bought, but not on my own board.

Can any one suggest what could be possible cause of the problem?

Thanks

xiaoqiang

Tesla DeLorean · ‎2012-08-24

Posted on August 24, 2012 at 13:32

Aren't pin 1 & 2 of the standard 20-pin ARM JTAG connector supposed to be VCC (board vs pod), not ground?

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emalund · ‎2012-08-24

Posted on August 24, 2012 at 20:14

I, when starting with a new chip, always insist on having a devboard, they are (usually) very cheap.

having a devboard enables a simple determination between

''is it my custom board''

OR

''is it (my use of) the tools''

Erik

cxu_dl · ‎2012-08-24

Posted on August 25, 2012 at 02:02

Clive1,

Found the problem, thank you. pin 1 should be Vref and pin 2 is optional 3.3V output, pins 4,6,8,...etc are grounds. But SWD does also require connecting Vref. The strange thing is the devboard works when connected the wrong way, but anyway..

So I modified J-link to bring out the 3.3V supply on pin 2, and use a jumper to connect pin 1 to pin2, that way I don't have to connect pin 1 to my board.

cxu_dl · ‎2012-08-24

Posted on August 25, 2012 at 02:06

Eric,

I do have a dev board, and got SWD working on it when connected the wrong way, which misled me to overlook the pin1, pin2 errors... but anyway thanks for the advice..