STM32F030K6 start only with reset tie to VCC

[piotr239955_st]

Posted on May 03, 2017 at 19:18

I have device with STM32f030K6T6. Since one moment, I am not able to start this uP without shorcircuiting nReset signal to VCC. Originally I had RC circuit on this line. When this problem had occured I modified it removing resistor (leaving capacitor connected between nReset and GND). Still doesn't work. Currently I'm running very simple program with for(;;) loop.

Main question is: what kind of setting may cause that? At some point I was using settings in ST-Link with 'Program under reset', but now I change that to 'normal & autodetect' but behavior is still the same.

Note: this post was migrated and contained many threaded conversations, some content may be missing.

[Tesla DeLorean]

Posted on May 03, 2017 at 19:23

I would guess you don't have VDDA wired up properly to a supply.

Short circuiting the pin suggests come chronic design failure on your end.

[piotr239955_st]

Posted on May 03, 2017 at 19:29

VDDA is connectected directly to VCC and 100nF capacitor is placed as close as possible.

[Tesla DeLorean]

Posted on May 03, 2017 at 19:38

If the supply is below threshold on VDDA the device will have NRST clamped internally.

If NRST with a pull-up is LOW, something in the circuit is driving it there or clamping. The STM32 won't naturally do that. You need to look critically at the circuits on the board, review the netlist carefully. Measure the voltage on VDDA.

Double check pin list against datasheet, and that part is correctly orientated.

[piotr239955_st]

Posted on May 03, 2017 at 21:53

It is weird, because it was working. The only thing I was changing, was firmware. I don't use ADC, so it should use default threshold value. To be sure, I set it up again in code, but still no differences. To program chip I need to keep this RST pin pulled up to VCC. Does anything else can influence on this pin?

[Tesla DeLorean]

Posted on May 04, 2017 at 00:17

Do you have any other GPIO, or net, that could short with it? Watch dog?

What did you change in the firmware between the time it worked and the time it failed? Did you do anything with the hardware, or introduce external voltages?

HSI should come on by default.

If you don't short NRST to VCC, what is the condition/profile of the signal? View on scope, power on board, etc.

[piotr239955_st]

Posted on May 04, 2017 at 16:15

On PCB J2 is standard SWD connector. As you can see, RST is connected only to RC and J2. It is not shorted to GND and to any other GPIO.I thought may I messed somehing in ''options bytes'', but I checked, they are setup (all checked) as in working project. I'm not sure what exactly I had changed when this first happend. For sure I was adding another module in firmware. No changes in hardware.

VDDA voltage

RESET signal

[waclawek.jan]

Posted on May 04, 2017 at 16:53

Leaky capacitor? Try to remove it.

JW

[piotr239955_st]

Posted on May 04, 2017 at 23:33

I will try tomorrow, but I have already replaced it with brand new one. Let me underline, device in this configuration was working. I'm more looking for internal setting that can cause this wrong behavior.