UART

UART Serial API.

API functions for bidirectional Asynchronous serial communications

Sysprops

sysprop	description
gpio_tx	RX GPIO
gpio_rx	TX GPIO
gpio_rts	RTS GPIO
gpio_cts	CTS GPIO

Functions Overview

	Name
CW_DRIVER_FUNC	uart_config(int hDev, uint32_t baudrate, uint8_t bits, uint8_t stop, uint8_t parity) configure baudrate and hardware protocol for the UART.
CW_DRIVER_FUNC	uart_write(int hDev, char * buf, size_t buflen, uint32_t timeout_ms) write a character sequence over the UART
CW_DRIVER_FUNC	uart_read(int hDev, char * buf, size_t buflen, uint32_t timeout_ms) read a character sequence from the UART

Defines

Name
UART_IOCTL_SEND_BREAK

Function Details

function uart_config

CW_DRIVER_FUNC uart_config(
    int hDev,
    uint32_t baudrate,
    uint8_t bits,
    uint8_t stop,
    uint8_t parity
)

configure baudrate and hardware protocol for the UART.

Parameters:

• hDev device handle as returned by open(const char*)
• baudrate desired baudrate. the peripheral driver documentation should be consulted for supported baudrates
• bits databits in the UART protocol, ususally 8
• stop number of stop-bits in the UART protocol. since 1.5 stop bits is no longer used in modern devices, it is not supported here.
• parity 0 for no parity, 1 for odd and 2 for even parity

function uart_write

CW_DRIVER_FUNC uart_write(
    int hDev,
    char * buf,
    size_t buflen,
    uint32_t timeout_ms
)

write a character sequence over the UART

Parameters:

• hDev device handle as returned by open(const char*)
• buf pointer to a char buffer. the buffer is not copied in the function, so it needs to be valid until the function returns.
• buflen length of the passed buffer.
• timeout_ms timeout in milliseconds to wait for the buffer to be transmitted

Return: 0 on successful write.

the function acts as blocking during a write to simplify the application architecture.

function uart_read

CW_DRIVER_FUNC uart_read(
    int hDev,
    char * buf,
    size_t buflen,
    uint32_t timeout_ms
)

read a character sequence from the UART

Parameters:

• hDev device handle as returned by open(const char*)
• buf buffer to hold the received characters.
• buflen length of the provided buffer
• timeout_ms timeout in milliseconds to wait for buflen characters to be returned

Return: number of characters read

the function will return after

• the timeout has passed.
• n > 0 characters have been received, followed by a timeout of at least 2 character-times.
• the passed buffer is full.

Macros Documentation

define UART_IOCTL_SEND_BREAK

#define UART_IOCTL_SEND_BREAK (0x0F01)