UART API

The ALP SDK UART driver provides a CMSIS-Driver compatible interface for asynchronous serial communication across all E1M modules.

Header

#include "alp_uart.h"

Initialization

#include "alp_uart.h"

/* Get the UART driver instance for channel 0 */
ALP_UART_Driver_t *uart = ALP_UART_GetDriver(0);

/* Initialize and power on */
uart->Initialize(uart_event_callback);
uart->PowerControl(ALP_POWER_FULL);

/* Configure: 115200 baud, 8N1 */
uart->Control(ALP_UART_MODE_ASYNCHRONOUS |
              ALP_UART_DATA_BITS_8 |
              ALP_UART_PARITY_NONE |
              ALP_UART_STOP_BITS_1,
              115200);

/* Enable TX and RX */
uart->Control(ALP_UART_CONTROL_TX, 1);
uart->Control(ALP_UART_CONTROL_RX, 1);

Sending Data

const char *msg = "Hello from ALP SDK\r\n";

uart->Send((const uint8_t *)msg, strlen(msg));
while (uart->GetStatus().tx_busy);

Receiving Data

uint8_t rx_buf[64];

uart->Receive(rx_buf, sizeof(rx_buf));
while (uart->GetStatus().rx_busy);

uint32_t count = uart->GetRxCount();
/* rx_buf contains 'count' bytes of received data */

Event Callback

void uart_event_callback(uint32_t event)
{
    if (event & ALP_UART_EVENT_RECEIVE_COMPLETE) {
        /* All requested bytes received */
    }
    if (event & ALP_UART_EVENT_SEND_COMPLETE) {
        /* Transmit buffer fully sent */
    }
    if (event & ALP_UART_EVENT_RX_OVERFLOW) {
        /* Receive buffer overrun */
    }
    if (event & ALP_UART_EVENT_RX_FRAMING_ERROR) {
        /* Framing error detected */
    }
}

Printf Redirect

A common pattern is to redirect printf() output to UART for debug logging:

#include <stdio.h>
#include "alp_uart.h"

static ALP_UART_Driver_t *debug_uart;

/* Retarget _write for newlib */
int _write(int fd, const char *buf, int len)
{
    (void)fd;
    debug_uart->Send((const uint8_t *)buf, len);
    while (debug_uart->GetStatus().tx_busy);
    return len;
}

void debug_uart_init(void)
{
    debug_uart = ALP_UART_GetDriver(0);
    debug_uart->Initialize(NULL);
    debug_uart->PowerControl(ALP_POWER_FULL);
    debug_uart->Control(ALP_UART_MODE_ASYNCHRONOUS |
                        ALP_UART_DATA_BITS_8 |
                        ALP_UART_PARITY_NONE |
                        ALP_UART_STOP_BITS_1,
                        115200);
    debug_uart->Control(ALP_UART_CONTROL_TX, 1);
}

API Reference

Functions

Function	Description
ALP_UART_GetDriver()	Get driver instance for a UART channel
Initialize()	Initialize the UART driver with callback
Uninitialize()	De-initialize and release resources
PowerControl()	Set power state
Control()	Configure baud rate, data format, flow control
Send()	Transmit data
Receive()	Start receiving data into a buffer
GetTxCount()	Get number of bytes transmitted
GetRxCount()	Get number of bytes received
GetStatus()	Get current driver status
Abort()	Abort send or receive operation

Events

Event	Description
ALP_UART_EVENT_SEND_COMPLETE	All data transmitted
ALP_UART_EVENT_RECEIVE_COMPLETE	Requested number of bytes received
ALP_UART_EVENT_RX_TIMEOUT	Receive timeout (inter-byte gap)
ALP_UART_EVENT_RX_OVERFLOW	Hardware receive buffer overrun
ALP_UART_EVENT_RX_FRAMING_ERROR	Stop bit not detected
ALP_UART_EVENT_RX_PARITY_ERROR	Parity mismatch

Supported Baud Rates

Common baud rates: 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600.