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142 lines
4.2 KiB
C
142 lines
4.2 KiB
C
/*
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* Copyright (C) 2020 ML!PA Consulting GmbH
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup drivers_soft_uart Software UART
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* @ingroup drivers_soft_periph
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* @brief Software implemented UART
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*
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* This module provides a software implemented Universal Asynchronous Receiver Transmitter.
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* It is intended to be used in situation where hardware UART is not available.
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* The signatures of the functions are similar to the functions declared in uart.h
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*
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* Currently sending and receiving is not possible at the same time, so loopback operation
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* is not possible.
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*
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* @{
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*
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* @file
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* @brief Software UART port descriptor definition
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*
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* @author Benjamin Valentin <benjamin.valentin@ml-pa.com>
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*/
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#ifndef SOFT_UART_H
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#define SOFT_UART_H
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#include "periph/gpio.h"
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#include "periph/uart.h"
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#include "periph/timer.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief invert the level of the TX signal
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*/
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#define SOFT_UART_FLAG_INVERT_TX 0x1
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/**
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* @brief invert the level of the RX signal
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*/
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#define SOFT_UART_FLAG_INVERT_RX 0x2
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/**
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* @brief Software UART port descriptor
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*/
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typedef struct {
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gpio_t rx_pin; /**< RX pin */
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gpio_t tx_pin; /**< TX pin */
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tim_t rx_timer; /**< Hardware timer used for RX */
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tim_t tx_timer; /**< Hardware timer used for TX */
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uint32_t timer_freq; /**< Operating frequency of the timer.
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Should be a multiple of baudrate */
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uint8_t flags; /**< Soft UART flags */
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} soft_uart_conf_t;
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/**
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* @brief Software UART type definition
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*/
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typedef unsigned soft_uart_t;
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/**
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* @brief Initialize a given UART device
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*
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* The UART device will be initialized with the following configuration:
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* - 8 data bits
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* - no parity
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* - 1 stop bit
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* - baudrate as given
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*
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* If no callback parameter is given (rx_cb := NULL), the UART will be
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* initialized in TX only mode.
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*
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* @param[in] uart UART device to initialize
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* @param[in] baudrate desired symbol rate in baud
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* @param[in] rx_cb receive callback, executed in interrupt context once
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* for every byte that is received (RX buffer filled),
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* set to NULL for TX only mode
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* @param[in] arg optional context passed to the callback functions
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*
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* @return UART_OK on success
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* @return UART_NODEV on invalid UART device
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* @return UART_NOBAUD on inapplicable baudrate
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* @return UART_INTERR on other errors
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*/
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int soft_uart_init(soft_uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg);
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/**
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* @brief Setup parity, data and stop bits for a given UART device
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*
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* @param[in] uart UART device to configure
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* @param[in] data_bits number of data bits in a UART frame
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* @param[in] parity parity mode
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* @param[in] stop_bits number of stop bits in a UART frame
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*
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* @return UART_OK on success
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* @return UART_NOMODE on other errors
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*/
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int soft_uart_mode(soft_uart_t uart, uart_data_bits_t data_bits, uart_parity_t parity,
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uart_stop_bits_t stop_bits);
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/**
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* @brief Write data from the given buffer to the specified UART device
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*
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* This function is blocking, as it will only return after @p len bytes from the
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* given buffer have been send. The way this data is send is up to the
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* implementation: active waiting, interrupt driven, DMA, etc.
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*
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* @param[in] uart UART device to use for transmission
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* @param[in] data data buffer to send
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* @param[in] len number of bytes to send
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*
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*/
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void soft_uart_write(soft_uart_t uart, const uint8_t *data, size_t len);
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/**
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* @brief Power on the given UART device
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*
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* @param[in] uart the UART device to power on
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*/
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void soft_uart_poweron(soft_uart_t uart);
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/**
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* @brief Power off the given UART device
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*
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* @param[in] uart the UART device to power off
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*/
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void soft_uart_poweroff(soft_uart_t uart);
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#ifdef __cplusplus
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}
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#endif
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#endif /* SOFT_UART_H */
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/** @} */
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