stm32 - Transfer data from RAM to Flash while ADC is running with DMA - Stack Overflow

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I have a STM32WB55VG device where ADC Sampling for one channel is happening at a rate of 40 kHz. As the sampling duration is about 5 seconds the data (400 kBytes) can not be stored in RAM (only 256 kBytes) only.

I was wondering, if the following method could work:

The DMA Controller stores the ADC Data directly to RAM. Once 4kBytes of data is stored in the RAM, the CPU writes this data to one page at the internal flash. While this writing to the flash occurs, the DMA Controller can still transfer the data from ADC to RAM.

As there´s only one bank available in the flash, the CPU is halted during writing to the flash. But the DMA should be able to continue the writing to the RAM?

This way I should be able to store all the data in the flash. Am I missing something here?

Thank you

I have a STM32WB55VG device where ADC Sampling for one channel is happening at a rate of 40 kHz. As the sampling duration is about 5 seconds the data (400 kBytes) can not be stored in RAM (only 256 kBytes) only.

I was wondering, if the following method could work:

The DMA Controller stores the ADC Data directly to RAM. Once 4kBytes of data is stored in the RAM, the CPU writes this data to one page at the internal flash. While this writing to the flash occurs, the DMA Controller can still transfer the data from ADC to RAM.

As there´s only one bank available in the flash, the CPU is halted during writing to the flash. But the DMA should be able to continue the writing to the RAM?

This way I should be able to store all the data in the flash. Am I missing something here?

Thank you

• stm32
• dma
• adc

Share Improve this question Follow asked Apr 2 at 1:32 JonasD2700JonasD2700 111 silver badge11 bronze badge New contributor JonasD2700 is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct. 1

• The datasheet indicates that writing a page of flash takes ~30-40ms. Your ADC will fill 4KB of RAM in 50ms (assuming 12-bit samples). So, from a timing perspective, it will be tight. But it sounds like it might work. – pmacfarlane Commented Apr 2 at 2:06

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This might work but it's not the best way of doing this because flash memories are not infinitely writeable/readable. STM32s flash typically have 10.000 cycles of flash endurance since it's not designed to be written into repetitiely. Although it might work after that amount of cycles, it's not guaranteed. You might wear the flash down and make it unusable after repetitive writes. The best option here would be connecting a SPI controlled volatile or non-volatile memory to your STM. Using QSPI would be better because it's memory mapped and faster than SPI. Choosing between volatile or non-volatile memory is completely based on your design choice.

You can find the list of possible ICs here

You need to consider the clock speed, write and read times, size and interface of the IC you choose according to your needs

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