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 elopes
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/*
* Copyright (C) 2014-2015 Freie Universitรคt Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup drivers_periph_uart UART
* @ingroup drivers_periph
* @brief Low-level UART peripheral driver
*
* This is a basic UART (Universal Asynchronous Receiver Transmitter) interface
* to allow platform independent access to the MCU's serial communication abilities.
* This interface is intentionally designed to be as simple as possible, to allow
* for easy implementation and maximum portability. In RIOT we only use the
* common 8-N-1 format of the serial port (8 data bits, no parity bit, one stop bit).
*
* The simple interface provides capabilities to initialize the serial communication
* module, which automatically enables for receiving data, as well as writing data
* to the UART port, which means transmitting data. The UART device and the
* corresponding pins need to be mapped in `RIOT/boards/ * /include/periph_conf.h`.
* Furthermore you need to select the baudrate for initialization which is typically
* {9600, 19200, 38400, 57600, 115200} baud. Additionally you should register a
* callback function that is executed in interrupt context when data is being received.
* The driver will then read the received data byte, call the registered callback
* function and pass the received data to it via its argument. The interface enforces
* the receiving to be implemented in an interrupt driven mode. Thus, you never know how
* many bytes are going to be received and might want to handle that in your specific
* callback function. The transmit function can be implemented in any way.
*
* By default the @p UART_DEV(0) device of each board is initialized and mapped to STDIO
* in RIOT which is used for standard input/output functions like `printf()` or
* `puts()`.
*
* @{
*
* @file
* @brief Low-level UART peripheral driver interface definition
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
*/
#ifndef PERIPH_UART_H
#define PERIPH_UART_H
#include <stddef.h>
#include <stdint.h>
#include <limits.h>
#include "periph_cpu.h"
#include "periph_conf.h"
/* TODO: remove once all platforms are ported to this interface */
#include "periph/dev_enums.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Define default UART type identifier
*/
#ifndef HAVE_UART_T
typedef unsigned int uart_t;
#endif
/**
* @brief Default UART undefined value
*/
#ifndef UART_UNDEF
#define UART_UNDEF (UINT_MAX)
#endif
/**
* @brief Default UART device access macro
*/
#ifndef UART_DEV
#define UART_DEV(x) (x)
#endif
/**
* @brief Signature for receive interrupt callback
*
* @param[in] arg context to the callback (optional)
* @param[in] data the byte that was received
*/
typedef void(*uart_rx_cb_t)(void *arg, uint8_t data);
/**
* @brief Interrupt context for a UART device
*/
#ifndef HAVE_UART_ISR_CTX_T
typedef struct {
uart_rx_cb_t rx_cb; /**< data received interrupt callback */
void *arg; /**< argument to both callback routines */
} uart_isr_ctx_t;
#endif
/**
* @brief Possible UART return values
*/
enum {
UART_OK = 0, /**< everything in order */
UART_NODEV = -1, /**< invalid UART device given */
UART_NOBAUD = -2, /**< given baudrate is not applicable */
UART_INTERR = -3, /**< all other internal errors */
UART_NOMODE = -4 /**< given mode is not applicable */
};
/**
* @brief Initialize a given UART device
*
* The UART device will be initialized with the following configuration:
* - 8 data bits
* - no parity
* - 1 stop bit
* - baudrate as given
*
* If no callback parameter is given (rx_cb := NULL), the UART will be
* initialized in TX only mode.
*
* @param[in] uart UART device to initialize
* @param[in] baudrate desired baudrate in baud/s
* @param[in] rx_cb receive callback, executed in interrupt context once
* for every byte that is received (RX buffer filled),
* set to NULL for TX only mode
* @param[in] arg optional context passed to the callback functions
*
* @return UART_OK on success
* @return UART_NODEV on invalid UART device
* @return UART_NOBAUD on inapplicable baudrate
* @return UART_INTERR on other errors
*/
int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg);
/**
* @brief Write data from the given buffer to the specified UART device
*
* This function is blocking, as it will only return after @p len bytes from the
* given buffer have been send. The way this data is send is up to the
* implementation: active waiting, interrupt driven, DMA, etc.
*
* @param[in] uart UART device to use for transmission
* @param[in] data data buffer to send
* @param[in] len number of bytes to send
*
*/
void uart_write(uart_t uart, const uint8_t *data, size_t len);
/**
* @brief Power on the given UART device
*
* @param[in] uart the UART device to power on
*/
void uart_poweron(uart_t uart);
/**
* @brief Power off the given UART device
*
* @param[in] uart the UART device to power off
*/
void uart_poweroff(uart_t uart);
#ifdef __cplusplus
}
#endif
#endif /* PERIPH_UART_H */
/** @} */
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