STM32F405RGT6 TIM Output Signal Becomes Unstable at 60°C While Room Temperature is Normal

[赤瞳plus]

 

Tests Performed and Results:
1.A DC regulated power supply was used to provide 14V to the board directly. At room temperature, the CPU's TIM pin output is normal. However, at high temperatures, the output waveform becomes intermittent.

2.The on-board 3.3V and 5V power supplies remain stable and within specification at all times.

3.The external crystal oscillator connected to the microcontroller maintains a stable waveform under all temperature conditions.

4.The same issue occurs even after replacing the CPU with one from a previous production batch: the TIM pin output is normal at room temperature but becomes intermittent at high temperatures.

5.This TIM pin is used to simulate a frequency signal. When the output becomes intermittent, the total output duration becomes longer. The firmware uses a pulse count to determine when to stop the output, so it appears the missing pulses (due to missed interrupts) cause the output to last longer than expected.

Questions:
Given the above results, what should I do next?

Should I contact ST technical support, and if so, how can I submit a support ticket correctly?

[TDK]

What is the waveform? Can you show the intermittent output on a scope plot?

[赤瞳plus]

Thank you for your reply. The normal and abnormal waveforms are shown in the attached video.

[赤瞳plus]

The waveforms were captured from the TIM1 pin using an oscilloscope.

[TDK]

It may be hard to diagnose further without knowing what the firmware is doing. Looks like it's not a standard PWM output but rather something dynamic. Even the periods between pulse trains seems variable in your video. The firmware is certainly doing something here.

 

I would guess that if you programmed a chip to output a basic PWM signal, it would work fine at 60 C.

 

ST support request can be made here, but I don't think they're going to be able to assist without more information.

https://ols.st.com/s/