Convert UART routines to interrupt routines problem

Projects Programming
1

Hello,

I am new to Arduino, so I have a few questions. I have this loop in my main program and want to move it to an interrupt based routine:

  while (Serial1.available()) {
                         Serial.print(char(Serial1.read()));
                                      };

It echoes the received data to the default uart0.
So I made a class in a header file with these routines:

#define WH24P_UART_NUM    UART_NUM_1
 #define Weather_RXD       37
 #define Weather_TXD       38
 #define Weather_Baudrate  9600
 const int TX_uart_buffer_size = 30;
 const int RX_uart_buffer_size = 512;
 const uart_config_t uart_config = {
.baud_rate = Weather_Baudrate,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE
        };

 void InitWH24P ()
 {
   ESP_ERROR_CHECK(uart_param_config(WH24P_UART_NUM, &uart_config));
   ESP_ERROR_CHECK(uart_set_pin(WH24P_UART_NUM, Weather_TXD, Weather_RXD, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
ESP_ERROR_CHECK(uart_driver_install(WH24P_UART_NUM, TX_uart_buffer_size * 2, RX_uart_buffer_size * 2, 0, NULL, 0));
ESP_ERROR_CHECK(uart_isr_free(WH24P_UART_NUM));
ESP_ERROR_CHECK(uart_isr_register(WH24P_UART_NUM,SerialEvent1, NULL, ESP_INTR_FLAG_IRAM, NULL));
ESP_ERROR_CHECK(uart_enable_rx_intr(WH24P_UART_NUM));
 }

 //static void IRAM_ATTR SerialEvent1(void *arg){ // doesn't work
 static void SerialEvent1(void *arg){ // UART RX event
   while (Serial1.available()) {
                         Serial.print(char(Serial1.read()));
                             };
   uart_clear_intr_status(WH24P_UART_NUM, UART_RXFIFO_FULL_INT_CLR|UART_RXFIFO_TOUT_INT_CLR);
 }

Why can I not use IRAM_ATTR? The code compiles without IRAM_ATTR. I get these errors with IRAM_ATTR : .iram1[WH24P::SerialEvent1(void*)]+0x3): dangerous relocation: l32r: literal placed after use:...
I saw that it had something to do with -mlongcalls. How can I check and change the compiler options? Please keep it stupid simple. Something like go to path c:\blabla and edit file file.ext. That would help.
I am using an ESP32 by the way.
Another question. The interrupt routine only constantly produces garbage on uart0. why is that? The routine was working well in my main program (echo data on uart0). Data is only received once every 16 seconds (21 bytes@9600Baud from the RS485 transceiver every 16 seconds).
I hope someone can help me. Thank you.

Best regards,
Mark

2

Hi,

I'm nowhere near a good programmer however I have recently been working with interrupts.

From what I understand, the compiler adds code that disables interrupts when you enter an interrupt, and vice versa on exiting the interrupt.

I'm not sure but I think Serial code uses interrupts. You might check this.

John

3

Why do you think that a serial read/write needs to be in an ISR? Unless you are running an extremely high baud rate there should be no problem keeping up with the serial input buffer. The previous post is also correct about serial needing interrupts, so it does not work inside an ISR while interrupts are disabled.

4

Data is only received once every 16 seconds (21 bytes@9600Baud from the RS485 transceiver every 16 seconds).

Have you ever heard of a wild goose chase?

5

Thank you for your answers, but does nobody know how to enable mlongcalls? that is messing up my code (reboots :frowning: )

6

markbng:
I have this loop in my main program and want to move it to an interrupt based routine:

What's wrong with the way you were doing it?

7

No. Why would we need to? The Arduino framework takes care of that for us.

If you think you need interrupts for this task then you are doing something wrong or you're using something different to Arduino.