IMXRT UART communication on Zephyr with ISR

[srinivasa2005]

Hi 

I am using IMXRT1064 EVK to communicate with GSM module over UART using ISR on Zephyr OS. 

uart_fifo_read always reading 4 bytes from the buffer and post that it returns number of bytes is 0. this API works well if the response is less than  4 bytes. If the response is more than 4 bytes, I am not getting the complete data from the FIFO.

1. Do we need to change the FIFO size? If we need to change, where is the place to update?

2. CTS and RTS to be enabled? if to enable,  there is no option on IMXRT1064 EVK UART pinouts.

Here is UART config 

struct uart_config cfg;

    cfg.baudrate = p_baudrate;

    cfg.data_bits = UART_CFG_DATA_BITS_8;

    cfg.parity = UART_CFG_PARITY_NONE;

    cfg.stop_bits = UART_CFG_STOP_BITS_1;

    cfg.flow_ctrl = UART_CFG_FLOW_CTRL_NONE;

Here is the Callback to read the FIFO 

/*void NXPUart::UartCb(const struct device* dev, void* user_data)

{

    NXPUart* instance = static_cast<NXPUart*>(user_data);

    auto& logger = Logger::GetInstance();

    if (!instance->uart_dev_)

    {

        logger.Error("UART device not initialized");

        return;

    }

    uint8_t buffer[UART_FIFO_SIZE];

    std::lock_guard<std::mutex> lock(instance->data_mutex_);

    int total_bytes_read = 0;

    while (uart_irq_update(dev) && uart_irq_is_pending(dev))

    {

        // Check if RX IRQ is ready

        if (uart_irq_rx_ready(dev))

        {

            int l_num_bytes_read = 0;

            do

            {

                // Read data in chunks into the buffer

                l_num_bytes_read = uart_fifo_read(dev, buffer, UART_FIFO_SIZE);

                total_bytes_read += l_num_bytes_read;

                if (l_num_bytes_read > 0)

                {

                    // Insert the chunk of data into accumulated_data_

                    instance->accumulated_data_.insert(instance->accumulated_data_.end(), buffer, buffer + l_num_bytes_read);

                    logger.Info("Received chunk: %s", std::string(buffer, buffer + l_num_bytes_read).c_str());

                }

            } while (l_num_bytes_read > 0);

            // Debug: Check accumulated data

            logger.Info("Accumulated Data so far: %s", std::string(instance->accumulated_data_.begin(), instance->accumulated_data_.end()).c_str());

            // Check if accumulated data contains a complete response

            if (instance->is_complete_response_callback_)

            {

                bool is_complete = instance->is_complete_response_callback_(instance->accumulated_data_);

                if (is_complete)

                {

                    // If response is complete, process the accumulated data

                    if (instance->data_received_callback_)

                    {

                        instance->data_received_callback_(

                            instance->accumulated_data_.data(),

                            instance->accumulated_data_.size()

                        );

                    }

                    // Clear the accumulated data after processing the complete response

                    instance->accumulated_data_.clear();

                }

            }

        }

[Omar_Anguiano]

The RXFIFO size is 4 ( 32 data words).  It is a fixed value, a hardware attribute, not configurable.

Hardware control may be helpful, you can use another LPUART instance to have it available on the EVK, CTS and RTS are available on the RT1064 EVK pins over LPUART3.

Best regards,
Omar