drivers/uart_half_duplex: initial support

drivers/Makefile.dep

@@ -203,3 +203,9 @@ ifneq (,$(filter xbee,$(USEMODULE)))
   USEMODULE += xtimer
   USEMODULE += netif
 endif
+
+ifneq (,$(filter uart_half_duplex,$(USEMODULE)))
+    FEATURES_REQUIRED += periph_gpio
+    FEATURES_REQUIRED += periph_uart
+    USEMODULE += xtimer
+endif

drivers/Makefile.include

@@ -106,3 +106,6 @@ endif
 ifneq (,$(filter adxl345,$(USEMODULE)))
     USEMODULE_INCLUDES += $(RIOTBASE)/drivers/adxl345/include
 endif
+ifneq (,$(filter uart_half_duplex,$(USEMODULE)))
+    USEMODULE_INCLUDES += $(RIOTBASE)/drivers/uart_half_duplex/include
+endif

drivers/uart_half_duplex/Makefile

@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base

drivers/uart_half_duplex/include/uart_half_duplex.h

@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2017 Inria
+ *
+ * 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_uart_half_duplex half-duplex UART Driver
+ * @ingroup     drivers_actuators
+ *
+ * This module contains drivers for UART half-duplex communication bus.
+ * It needs to manage the communication direction by enabling or disabling TX.
+ *
+ * @{
+ *
+ * @file
+ * @brief       Interface definition for half-duplex UART driver
+ *
+ * @author      Loïc Dauphin <loic.dauphin@inria.fr>
+ */
+
+#ifndef UART_HALF_DUPLEX_H
+#define UART_HALF_DUPLEX_H
+
+#include <stdlib.h>
+
+#include "periph/uart.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef UART_HALF_DUPLEX_DEFAULT_TIMEOUT_US
+#define UART_HALF_DUPLEX_DEFAULT_TIMEOUT_US (20000LU) /**< Default recv timeout (in microseconds) */
+#endif
+
+/**
+ * @brief half-duplex UART direction management method type
+ */
+typedef int uart_half_duplex_dir_t;
+
+#define UART_HALF_DUPLEX_DIR_NONE           (0)  /**< Don't manage direction */
+
+#define UART_HALF_DUPLEX_DIR_PIN_SET(pin)   (((pin + 1) << 1))     /**< pin set enables TX */
+#define UART_HALF_DUPLEX_DIR_PIN_CLEAR(pin) (((pin + 1) << 1) | 1) /**< pin clear enables TX */
+
+/**
+ * @brief Configuration for half-duplex UART
+ */
+typedef struct {
+    uart_t uart;                /**< the half-duplex UART bus to use */
+    uint32_t baudrate;          /**< the baudrate to use */
+    uart_half_duplex_dir_t dir; /**< the direction management method */
+} uart_half_duplex_params_t;
+
+/**
+ * @brief Descriptor struct for half-duplex UART
+ */
+typedef struct {
+    uint8_t *buffer;                  /**< the buffer used for TX and RX */
+    size_t size;                      /**< the number of available elements for TX/RX */
+    size_t buffer_max_size;                     /**< the buffer size */
+    uint32_t timeout_us;              /**< the maximum duration (in microseconds) for waiting data */
+    uart_half_duplex_params_t params; /**< the half-duplex UART configuration */
+} uart_half_duplex_t;
+
+/**
+ * @brief   Possible UART_HALF_DUPLEX return values
+ */
+enum {
+    UART_HALF_DUPLEX_OK     = UART_OK,       /**< everything in order */
+    UART_HALF_DUPLEX_NODEV  = UART_NODEV,    /**< invalid UART device given */
+    UART_HALF_DUPLEX_NOBAUD = UART_NOBAUD,   /**< given baudrate is not applicable */
+    UART_HALF_DUPLEX_INTERR = UART_INTERR,   /**< all other internal errors */
+    UART_HALF_DUPLEX_NOMODE = UART_NOMODE,   /**< given mode is not applicable */
+    UART_HALF_DUPLEX_NOBUFF = -5             /**< invalid buffer given */
+};
+
+/**
+ * @brief Initialize the half-duplex UART bus to communicate with devices
+ *
+ * @param[out] dev             the device
+ * @param[in] buffer           the buffer used for TX and RX
+ * @param[in] buffer_max_size  the buffer size
+ * @param[in] params           the initialization parameters
+ *
+ * @return     UART_HALF_DUPLEX_OK if everything is in order
+ * @return     UART_HALF_DUPLEX_NODEV if invalid UART device was given
+ * @return     UART_HALF_DUPLEX_NOBAUD if given baudrate is not applicable
+ * @return     UART_HALF_DUPLEX_INTERR if an other internal error occured
+ * @return     UART_HALF_DUPLEX_NOMODE if the given mode is not applicable
+ * @return     UART_HALF_DUPLEX_NOBUFF if an invalid buffer was given
+ */
+int uart_half_duplex_init(uart_half_duplex_t *dev, uint8_t *buffer, size_t buffer_max_size, const uart_half_duplex_params_t *params);
+
+/**
+ * @brief Set the half-duplex UART bus in TX mode
+ *
+ * @param[in] dev        the device
+ */
+static inline void uart_half_duplex_set_tx(uart_half_duplex_t *dev)
+{
+    dev->size = dev->buffer_max_size;
+}
+
+/**
+ * @brief Set the half-duplex UART bus in RX mode
+ *
+ * @param[in] dev        the device
+ */
+static inline void uart_half_duplex_set_rx(uart_half_duplex_t *dev)
+{
+    dev->size = 0;
+}
+
+/**
+ * @brief Send the data contained in the driver's buffer
+ *
+ * @param[in] dev        the device
+ * @param[in] size       the number of characters to send
+ *
+ * @return               the number of characters actually sent
+ */
+size_t uart_half_duplex_send(uart_half_duplex_t *dev, size_t size);
+
+/**
+ * @brief Recv data an fill the driver's buffer
+ *
+ * @param[in] dev        the device
+ * @param[in] size       the number of characters to receive
+ *
+ * @return               the number of characters actually received
+ */
+size_t uart_half_duplex_recv(uart_half_duplex_t *dev, size_t size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/** @} */

drivers/uart_half_duplex/uart_half_duplex.c

@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2017 Inria
+ *
+ * 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.
+ */
+
+/**
+ * @ingroup     drivers_uart_half_duplex
+ * @{
+ *
+ * @file
+ * @brief       Driver implementation for half-duplex UART devices
+ *
+ * @author      Loïc Dauphin <loic.dauphin@inria.fr>
+ *
+ * @}
+ */
+
+#include "uart_half_duplex.h"
+
+#include "periph/uart.h"
+#include "periph/gpio.h"
+#include "xtimer.h"
+
+#define IS_SET(dir)   ((dir & 1) == 0)
+#define IS_CLEAR(dir) ((dir & 1) == 1)
+
+#define IS_PIN(dir)    (dir >= UART_HALF_DUPLEX_DIR_PIN_SET(0))
+#define GET_PIN(dir)   ((dir >> 1) - 1)
+
+static inline void _enable_tx(uart_half_duplex_dir_t dir)
+{
+    if (IS_PIN(dir)) {
+        if (IS_SET(dir)) {
+            gpio_set(GET_PIN(dir));
+            return;
+        }
+        if (IS_CLEAR(dir)) {
+            gpio_clear(GET_PIN(dir));
+            return;
+        }
+    }
+}
+
+static inline void _disable_tx(uart_half_duplex_dir_t dir)
+{
+    if (IS_PIN(dir)) {
+        if (IS_SET(dir)) {
+            gpio_clear(GET_PIN(dir));
+            return;
+        }
+        if (IS_CLEAR(dir)) {
+            gpio_set(GET_PIN(dir));
+            return;
+        }
+    }
+}
+
+static void _rx_cb(void* data, uint8_t c)
+{
+    uart_half_duplex_t *dev = data;
+    if (dev->size < dev->buffer_max_size) {
+        dev->buffer[dev->size++] = c;
+    }
+}
+
+int uart_half_duplex_init(uart_half_duplex_t *dev, uint8_t *buffer, size_t buffer_max_size, const uart_half_duplex_params_t *params)
+{
+    if (buffer == NULL || buffer_max_size <= 7) {
+        return UART_HALF_DUPLEX_NOBUFF;
+    }
+
+    dev->buffer = buffer;
+    dev->buffer_max_size = buffer_max_size;
+    dev->params = *params;
+    dev->timeout_us = UART_HALF_DUPLEX_DEFAULT_TIMEOUT_US;
+
+    if (IS_PIN(dev->params.dir)) {
+        gpio_init(GET_PIN(dev->params.dir), GPIO_OUT);
+    }
+
+    int ret = uart_init(dev->params.uart, dev->params.baudrate, _rx_cb, dev);
+
+    _disable_tx(dev->params.dir);
+    uart_half_duplex_set_rx(dev);
+
+    return ret;
+}
+
+size_t uart_half_duplex_send(uart_half_duplex_t *dev, size_t size)
+{
+    _enable_tx(dev->params.dir);
+    uart_write(dev->params.uart, dev->buffer, size);
+    _disable_tx(dev->params.dir);
+    return size;
+}
+
+size_t uart_half_duplex_recv(uart_half_duplex_t *dev, size_t size)
+{
+    const uint32_t begin = xtimer_now_usec();
+    while (xtimer_now_usec() - begin < dev->timeout_us) {
+        if (dev->size >= size) {
+            break;
+        }
+    }
+    return dev->size;
+}