ADC Analog Watchdog (AWD) Interrupt-Disable and Enable again at Runtime

[ETX]

I'm using the AWD (STM32G0B0CE) with the HAL_ADC_LevelOutOfWindowCallback(), which works fine.
For not blocking the MCU completely, I'm disabeling the AWD-IT inside the Callback when fired for about 500ms:
LL_ADC_DisableIT_AWD1 (ADC1);
After the 500ms elapsed the AWD-IT is enabled again:
LL_ADC_EnableIT_AWD1 (ADC1);

This only works fine for about 2 times:
Start -> Fire IT -> DisableIT
-> 500ms
-> EnableIT -> Fire IT -> DisableIT
-> 500ms
-> IT stays completely disabled, though enabled again.

Any idea what I'm missing?
Thanks.

[waclawek.jan]

> IT stays completely disabled,

How do you know? Have you observed the respective control flags in ADC? A generic "interrupt does not fire" guide here. As you appear to use Cube/HAL, the problem may be also in Cube/HAL's fabric, I don't use it but it's open source so you can check yoruself.

JW

[ETX]

Thanks for your answer!

Reading the reference manual (rm0454-stm32g0x0) about the ADC interrupt enable register (ADC_IER), it says AWD1IE (Analog watchdog 1 interrupt enable) can only be set, when ADSTART bit is cleared.

The ADSTART bit is part of the ADC control register (ADC_CR) and is cleared by hardware after each conversion.

As I'm running in continous conversion mode, I suppose ADSTART is never cleared by hardware.

So tried to clear it manually while enabling AWD1IE again.

ADC1->CR &= ~ADC_CR_ADSTART; // Clear ADSTART in ADC control register (ADC_CR)
ADC1->IER|=ADC_IER_AWD1IE; // Enable AWD-interrupt in ADC IR enable register (ADC_IER)
    // LL_ADC_EnableIT_AWD1 (ADC1); // also doesn't work
ADC1->CR |= ADC_CR_ADSTART;     // Set ADSTART in ADC control register (ADC_CR)

But unfortunately this does'nt also work, as clearing the ADSTART bit doesn't seem to work.

As I'm just new to STM32 MCUs, maybe someone could give some more advice.

Thanks!

[waclawek.jan · Accepted solution]

ADC_CR.ADSTART can't be cleared by writing 0 to it; you stop conversions by setting ADC_CR.ADSTP and that in hardware clears ADC_CR.ADSTART. This is not immediate, you are supposed to read back ADC_CR.ADSTP until it autoclears.

But I personally wouldn't do that. I would try to avoid triggering the interrupt by setting the watchdog thresholds so that no ADC result triggers it.

JW

[ETX]

Thanks for your idea!
This really sounds a better solution....