STM32F302 Adc with DMA for different size and channel

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votes

I'm using STM32F302 QFN32 and unfortunately, it has only one ADC module. One channel must get around 500 samples in one period and it must be sync with and PWM (thinking using a timer and this i/o will be toggled in callback, because while reading its ADC channel, I must know the i/o whether high or low, so that according to this value, will decide value). Furthermore, there are 4 more channels which must be read.(More samples doesn't need there like before, 8 or 16 samples will be enough.) However, it has only one ADC module. Consequently, Can I do this? If yes, how? Thank you.

1
stm32
"I'm using STM32F302 QFN32" - quite interesting as this micro is not manufactured in the QFN32 case – 0___________
I mentioned UFQFPN is its case. – Gokhan Sahin
ST has the package in the full order code, can you give the full order code? STM32F302xxx? Im guessing an x6x or x8x? – Jeroen3
It's STM32F302K8U6. – Gokhan Sahin

1 Answers

2
votes

ST ADC have two conversion modes. Regular and Injected.

Regular mode is like all ADC's have. You start it, either by software or trigger (timer/gpio) and it does one or a sequence of conversions. The result is written to a common register, that the DMA takes care of.
Injected mode is a high priority preemption conversion. Once you start an injected conversion sequence by software or trigger. The ADC injects the conversion between the regular conversions. As a higher priority one. The result is stored in one of the injected result channel for the interrupt.
Only regular mode supports DMA. See AN4195 for more info.

I suggest you use a timer to trigger a regular sequence for your fast channel, with a circular DMA setup to move the data. And use another timer to trigger the injected sequence. There is a maximum of 4 injected channels, so you are in luck!

Obviously, you can do this the other way around. Have fast injections and slow regular. But you'll need another timer synchronized to the injected start trigger to get the DMA to move the data.
That is, if your samplerate does not allow immediate processing. Otherwise you can just use the ISR.