Marvee Amasi Posts - Answer Overflow

Marvee Amasi

•Created by Marvee Amasi on 5/23/2024 in #middleware-and-os

Using atomic operations to update the SPI busy flag in FreeRTOS

Hi everyone @Middleware & OS , I'm working on an embedded project using FreeRTOS . I encountered a scenario where I need to atomically clear an SPI busy flag (spiTxRxByteCount) to ensure thread safety. Disabling interrupts is a common approach, but I was wondering if we could achieve the same outcome using atomic operations provided by FreeRTOS.

static void ClearSpiBusyFlag(void) {
  uint8_t new_state = spiTxRxByteCount & ~0x0100;
  spiTxRxByteCount = AtomicCompareSet(spiTxRxByteCount, new_state);
}

static void ClearSpiBusyFlag(void) {
  uint8_t new_state = spiTxRxByteCount & ~0x0100;
  spiTxRxByteCount = AtomicCompareSet(spiTxRxByteCount, new_state);
}

My current approach utilizes a function like ClearSpiBusyFlag that leverages AtomicCompareSet to update the flag atomically. Is this a valid approach, or are there potential drawbacks compared to interrupt disabling? In your experience, what are the best practices for handling such scenarios in FreeRTOS development?

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