ESP8266 Community Forum

Posted: **Sun Dec 14, 2014 7:56 am**

I did some digging into RTOS-SDK, and found ets_isr_attach was removed from the library. Instead, some interrupt related code seems to be move to port.c of freertos.

I wonder under such arrangement how can I write an ISR for example UART RX handler?

Any help will be appreciated.

BS

Posted: **Thu Dec 25, 2014 8:48 pm**

Answer my own questions:
Here is my UART initialization:

Code: Select all

void ICACHE_FLASH_ATTR uart0_init(uart_param_t* param, uart_rx_handler_t rx_handler)
{
    portENTER_CRITICAL();

    _rx_handler = rx_handler;

    PIN_PULLUP_DIS(PERIPHS_IO_MUX_U0TXD_U);
    PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0TXD_U, FUNC_U0TXD);

    WRITE_PERI_REG(UART_CLKDIV(UART0), UART_CLK_FREQ / (param->uart_baud_rate));

    WRITE_PERI_REG(UART_CONF0(UART0),
        param->uart_parity_mode
        |
        (param->uart_stop_bit << UART_STOP_BIT_NUM_S)
        |
        (param->uart_xfer_bit << UART_BIT_NUM_S));

    // Clear RX and TX FIFO
    SET_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);
    CLEAR_PERI_REG_MASK(UART_CONF0(UART0), UART_RXFIFO_RST | UART_TXFIFO_RST);

    // Clear all interrupt
    WRITE_PERI_REG(UART_INT_CLR(UART0), 0x1ff);

    _xt_isr_attach(ETS_UART_INUM, _uart0_rx_isr);

    // RX interrupt conditions: FIFO full (1 char)
    SET_PERI_REG_MASK(UART_CONF1(UART0), ((0x01 & UART_RXFIFO_FULL_THRHD) << UART_RXFIFO_FULL_THRHD_S));

    // Enable RX Interrupt
    SET_PERI_REG_MASK(UART_INT_ENA(UART0), UART_RXFIFO_FULL_INT_ENA | UART_FRM_ERR_INT_ENA);

    _xt_isr_unmask(1 << ETS_UART_INUM);  // ETS_UART_INTR_ENABLE();

    portEXIT_CRITICAL();
}

Set interrupt handler

Code: Select all _xt_isr_attach(ETS_UART_INUM, _uart0_rx_isr);

Enable interrupt.

Code: Select all_xt_isr_unmask(1 << ETS_UART_INUM);

Here is the ISR

Code: Select all

LOCAL uart_rx_handler_t _rx_handler = 0;

LOCAL void _uart0_rx_isr(void)
{
    char ch;

    // Frame error, ignore and continue
    if (UART_FRM_ERR_INT_ST == (READ_PERI_REG(UART_INT_ST(UART0)) & UART_FRM_ERR_INT_ST))
    {
        // printf("FRM_ERR\r\n");
        WRITE_PERI_REG(UART_INT_CLR(UART0), UART_FRM_ERR_INT_CLR);
    }
    // RX FIFO FULL
    else if (UART_RXFIFO_FULL_INT_ST == (READ_PERI_REG(UART_INT_ST(UART0)) & UART_RXFIFO_FULL_INT_ST))
    {
        //os_printf("RX_FULL\r\n");
        while (READ_PERI_REG(UART_STATUS(UART0)) & (UART_RXFIFO_CNT << UART_RXFIFO_CNT_S))
        {
            ch = READ_PERI_REG(UART_FIFO(UART0)) & 0xFF;
            if (_rx_handler)
                _rx_handler(ch);
        }
        WRITE_PERI_REG(UART_INT_CLR(UART0), UART_RXFIFO_FULL_INT_CLR);
    }
}

I found I shall not disable or enable interrupt inside the ISR. Otherwise some exceptions occur.

Posted: **Thu Jan 01, 2015 3:44 pm**

Hi Baoshi,

Thanks for sharing your experience.

I need to do this too, but i can't compile your code.

I can't find out some typedefs (like: uart_param_t, uart_rx_handler_t) and some things like: UART0, _uart0_rx_isr, etc.

Could you help me?

Thanks

Posted: **Sun Jan 04, 2015 8:48 am**

Use the code from http://bbs.espressif.com/viewtopic.php?f=7&t=100 instead. Better than mine.

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