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liampwll · 2024-07-21

I'm trying to use DMA with the USART2 receiver in half-duplex mode but the DMA indicates a device error as soon as it begins even though no error flag is set in the ISR register either before the DMA starts or after the DMA ends, additionally the sam...

liampwll · 2024-07-21

That's an annoying thing for them to not document, especially when the RM explicitly says that the error only occurs when an address is in the reserved space, not an inaccessible-to-DMA space. I've just moved the buffer out of CCM, which solves the p...

liampwll · 2024-07-21

> How did you come to this conclusion?I thought that ISR.TEIFx was set when the peripheral that was being read from indicated an error, however this appears to not be the case, instead it is set when reading from or writing to a reserved address spac...

liampwll · 2024-07-21

> So, how would DMA indicate an error in any other way than setting a flag in the DMA_ISR register?To be clear I mean there is no error in the USART ISR register. The DMA ISR register error flags have no reason to be set in this case.

liampwll · 2024-07-21

I forgot DMAMUX:DMAMUX.C1CR: (DMAREQ_ID => 26, RESERVED_7_7 => 0, SOIE => FALSE, EGE => FALSE, RESERVED_10_15 => 0, SE => FALSE, SPOL => 0, NBREQ => 0, SYNC_ID => 0, RESERVED_29_31 => 0)

liampwll · 2024-07-21

This is Ada and nothing is touching the ISR register in between these two calls. Poll_For_Completion only looks at the ISR on the DMA, and the error indicates that ISR.TEIF1 is set. Here's a dump of the relevant USART2 and DMA registers. I can conver...

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USART DMA immediately indicates error but no error flag is set

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