2012-08-24 12:27 AM
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 xiaoqiang2012-08-24 04:32 AM
Aren't pin 1 & 2 of the standard 20-pin ARM JTAG connector supposed to be VCC (board vs pod), not ground?
2012-08-24 11:14 AM
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'' Erik2012-08-24 05:02 PM
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.2012-08-24 05:06 PM
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..