ESP32 Forum

Posted: **Wed Feb 08, 2023 2:51 pm**

Hi, so I`m using UART communication between ESP32 and AVR chip. Having issue with TX response rate.

AVR is sending 5 bytes, first two are command bytes and last 3 are data bytes:

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//command
Serial2.write(0x01);
Serial2.write(0x62);
//data
Serial2.write(0x69); //high byte
Serial2.write(0x70); //low byte
Serial2.write(0x71); //data
  
delayMicroseconds(150);

And on the ESP side its using RX interrupt to get and store data into another buffer and xTaskResumeFromISR to do something with recieved data:

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static void IRAM_ATTR uart_intr_handle(void *arg)
{
    uint16_t i = 0;
    uint16_t rx_fifo_len = 0;
    rx_fifo_len = UART1.status.rxfifo_cnt; // read number of bytes in UART buffer
    
    while(rx_fifo_len){
    rxbuf[i++] = UART1.fifo.rw_byte; // read all bytes

        if(rxbuf[i] == 0x01 && rxbuf[i+1] == 0x62){
            dataBuff[0] = rxbuf[i + 2];
            dataBuff[1] = rxbuf[i + 3];
            dataBuff[2] = rxbuf[i + 4];

            xTaskResumeFromISR(xHandle);
        }

        if(rxbuf[i] == 0x02 && rxbuf[i+1] == 0x63){
            // xTaskResumeFromISR(xHandle2);
        }

        rx_fifo_len--;
    }
    uart_clear_intr_status(EX_UART_NUM, UART_RXFIFO_FULL_INT_CLR|UART_RXFIFO_TOUT_INT_CLR);
}

This is function where it processes that data:

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void task(void *arg){
    while(1){
        char writeAddress[6];
        uint16_t tempAddress = dataBuff[1] | (dataBuff[0]<<8);
        uint8_t writeData = dataBuff[2];

        sprintf(writeAddress, "%d", tempAddress);
        ESP_LOGE("uart", "Address: %s, %x", writeAddress, writeData);
        
        //not implemented yet, but here is where data will be stored into esp nvs
        //and send 0x01 back to AVR so it knows that datas has been stored succesfully

        uart_write_bytes(EX_UART_NUM, &txDataBuff[1], 1);

        vTaskSuspend(NULL);
    }
}

Data im getting is correct and here is glimpse of ESP_LOGE:

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E (2290198) uart: Address: 26992, 71
E (2290198) uart: Address: 26992, 71
E (2290208) uart: Address: 26992, 71
E (2290208) uart: Address: 26992, 71
E (2290218) uart: Address: 26992, 71
E (2290218) uart: Address: 26992, 71

So my issue is that it takes about 5 milliseconds to uart_write_bytes() (so it also means that function takes 5ms to complete?):

This is a closeup of packet:

Trying to send response on every data packed received, but it looks like it just sends every ~30 packet.

I`m assuming that its something to do with how long time it takes to resume task or another task is interrupting this task?

How can i increase response time?

Your`e response will be greatly appreciated

ESP32 Forum

ESP32 and AVR UART communication issue

ESP32 and AVR UART communication issue