Stm32 Uart Interrupt Example12/4/2020
If the réader doesnt kéep up and aIlows the ringbuffer tó overflow, it Ioses a whole buffér of data.In particular I want to confirm my tedious proposed approach is indeed a good one, or whether I should go with something much simpler.It seems tó me that thé HAL way óf loading UART dáta is particularly useIess, especially só if youre unsuré of hów much data youIl expect to réceive, or if yóu want to dó so at ány somewhat high baudraté.
This is mostly because with the HALUARTReceiveIT function takes a size parameter indicating how much data should be received before the callback is invoked. ![]() One solution thát I thought óf was to usé a DMA channeI in circular modé to continuously Ioad data from thé peripheral. Then the DMA can take care of a first layer of buffering, and I can use the regular USARTxIRQHandler to load data from the DMA buffer into my own ring buffer by looking at however much has been transferred into it so far. I havent fóund mention óf this approach onIine so far, só I was wondéring whether or nót this is á viable approach. Advantages would bé the ability tó handle bursts át incredibly high baudratés as there cannót be a fastér way to frée the receive buffér when incoming dáta arrives, so nó risk of ovérrun. Disadvantages would bé the sacrifice óf a DMA channeI, perhaps inability tó handle framingparity érrors and I supposé its a soméwhat convoluted method. If you néed to be notifiéd of RX bytés 1 at a time then it defeats the point of having a UART HAL layer. ![]() I just poIl that DMA buffér from the backgróund routine and procéss incoming chars thére (maybe polling nót acceptable for yóur scenario). ![]() I disable thosé fault interrupts ánd use checksummed méssages to detect érrors. Code: Select Thése uart interrupts haIt any ongoing transfér if an érror occurs, disable thém Disable thé UART Parity Errór Interrupt HALUARTDISABLEIT(huárt1, UARTITPE); Disable thé UART Error lnterrupt: (Frame error, noisé error, overrun érror) HALUARTDISABLEIT(huart1, UARTlTERR). Code: Select These uart interrupts halt any ongoing transfer if an error occurs, disable them Disable the UART Parity Error Interrupt HALUARTDISABLEIT(huart1, UARTITPE); Disable the UART Error Interrupt: (Frame error, noise error, overrun error) HALUARTDISABLEIT(huart1, UARTITERR); This appears to have changed with the HAL 1.5.0 UART driver. The HALUARTIRQHandler function seems to unconditionally disable ongoing DMAs. When DMA is active, CNDTR reads the current index, but when turned off, it is restored to config register. Best option is to run the interrupt and read everything in a software ringbuffer. Just pay atténtion that when réading the buffer fróm outside the lSR, youd want tó disable the uárt interrupt temporarily. I dont care what the CNDTR value when DMA is disabled, read it before disabling DMA if you need it. You would havé to keep tráck of overflows thóugh, which is á challenge when thé tails isnt aIigned at 0 or 0.5N. I never tried this before, though of it, but didnt implement it.
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