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problem on watchdog

Associate II
Posted on August 05, 2013 at 14:51

Hi everbody,

I'm using a ST32F205VE. On my board, I'm using the internal watchdog of the microcontroller and an external watchdog (MCP1318T).

During normal operation, the �c sends square pulses every 0.5s to the external watchdog. When the �c stops sending pulses, the external watchdog sends me a rising edge.

Then, the �c is restarting because So it works well.

My issue is when the �c is restarting (with his internal watchdog), I got something strange, because the pulses that the �c is sending to the external watchdog are 3 times longer (0.5s to 1.5s) and I've changed nothing in my configuration.

I'm looking for explanations in the datasheet, but I've found nothing...

If you've some ideas...thank you in advance.

Associate II
Posted on August 05, 2013 at 15:44

How do you generate the reset pulse to the external watchdog?  Keep in mind that after a reset the STM32 runs on the HSI internal oscillator clock until you change to HSE and/or set the PLL multiplier.

  Jack Peacock