Serial interrupts and LittlsFS together

[grunnels@gmail.com]

Is there a way to use LittleFS and not drop any serial data? I'm capturing about 8k of serial data per minute and writing to a littleFS file. When the file write happens, interrupts are disabled and I lose serial data. Hardware is an ESP32-S3. Serial is read over GPIO 4 & 5.

[adokitkat]

Hello. You should be able to do so by putting the ISR handler function into IRAM and registering it under the IRAM interrupt flag:

Code: Select all

void IRAM_ATTR my_critical_isr_handler(void *arg) {
    // This ISR can run even during flash operations
    // BUT: it must NOT access any data in flash either!
    // Any function this function calls also HAS to be in IRAM
    // Any data this function access has to be placed in DRAM (DRAM_ATTR), e.g.: `static const uint8_t DRAM_ATTR lookup[] = {0, 1, 2, 3};`
}

//...

esp_err_t ret = esp_intr_alloc(ETS_GPIO_INTR_SOURCE,
                                ESP_INTR_FLAG_IRAM | ESP_INTR_FLAG_LEVEL1,
                                my_critical_isr_handler,
                                NULL,
                                NULL);

This is more advanced feature so please read the documentation thoroughly.
https://docs.espressif.com/projects/esp ... t-handlers
https://docs.espressif.com/projects/esp ... uction-ram
https://docs.espressif.com/projects/esp ... io_isr_tPv
https://docs.espressif.com/projects/esp ... nc-in-iram

What: In Flash (Default) -> Move to IRAM

• Functions: Regular functions -> IRAM_ATTR
• Called sub-functions: Normal calls -> Must also be IRAM_ATTR
• Const data / tables: const, static const -> DRAM_ATTR
• String literals: "hello" -> Use DRAM_ATTR char arrays
• Logging: ESP_LOGx() -> esp_rom_printf()
• GPIO control: gpio_set_level() -> Direct register access or place GPIO function into IRAM (CONFIG_GPIO_CTRL_FUNC_IN_IRAM)