cpu/nrf52: add i2c driver and configs

boards/acd52832/include/periph_conf.h

@@ -96,6 +96,21 @@ static const spi_conf_t spi_config[] = {
 #define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
 /** @} */
 
+/**
+ * @name    I2C configuration
+ * @{
+ */
+static const i2c_conf_t i2c_config[] = {
+    {
+        .dev     = NRF_TWIM0,
+        .pin_scl = 28,
+        .pin_sda = 29
+    }
+};
+
+#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif

boards/common/nrf52xxxdk/Makefile.features

@@ -1,5 +1,6 @@
 # Put defined MCU peripherals here (in alphabetical order)
 FEATURES_PROVIDED += periph_gpio
+FEATURES_PROVIDED += periph_i2c
 FEATURES_PROVIDED += periph_rtt
 FEATURES_PROVIDED += periph_spi
 FEATURES_PROVIDED += periph_timer

boards/common/nrf52xxxdk/include/periph_conf.h

@@ -93,6 +93,21 @@ static const spi_conf_t spi_config[] = {
 #define SPI_NUMOF           (sizeof(spi_config) / sizeof(spi_config[0]))
 /** @} */
 
+/**
+ * @name    I2C configuration
+ * @{
+ */
+static const i2c_conf_t i2c_config[] = {
+    {
+        .dev     = NRF_TWIM0,
+        .pin_scl = 28,
+        .pin_sda = 29
+    }
+};
+
+#define I2C_NUMOF           (sizeof(i2c_config) / sizeof(i2c_config[0]))
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif

cpu/nrf52/include/periph_cpu.h

@@ -75,6 +75,29 @@ typedef enum {
 } adc_res_t;
 /** @} */
 
+/**
+ * @brief   Override I2C speed settings
+ * @{
+ */
+#define HAVE_I2C_SPEED_T
+typedef enum {
+    I2C_SPEED_LOW       = 0xff,                         /**< not supported */
+    I2C_SPEED_NORMAL    = TWI_FREQUENCY_FREQUENCY_K100, /**< 100kbit/s */
+    I2C_SPEED_FAST      = TWI_FREQUENCY_FREQUENCY_K400, /**< 400kbit/s */
+    I2C_SPEED_FAST_PLUS = 0xfe,                         /**< not supported */
+    I2C_SPEED_HIGH      = 0xfd,                         /**< not supported */
+} i2c_speed_t;
+/** @} */
+
+/**
+ * @brief   I2C (TWI) configuration options
+ */
+typedef struct {
+    NRF_TWIM_Type *dev;         /**< hardware device */
+    uint8_t pin_scl;            /**< SCL pin */
+    uint8_t pin_sda;            /**< SDA pin */
+} i2c_conf_t;
+
 #ifdef __cplusplus
 }
 #endif

cpu/nrf52/periph/i2c.c

@@ -0,0 +1,209 @@
+/*
+ * Copyright (C) 2017 HAW Hamburg
+ *
+ * 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     cpu_nrf52
+ * @{
+ *
+ * @file
+ * @brief       Low-level I2C driver implementation
+ *
+ * @author      Dimitri Nahm <dimitri.nahm@haw-hamburg.de>
+ *
+ * @}
+ */
+
+#include "cpu.h"
+#include "mutex.h"
+#include "assert.h"
+#include "periph/i2c.h"
+#include "periph_conf.h"
+
+#define ENABLE_DEBUG        (0)
+#include "debug.h"
+
+/**
+ * @brief   If any of the 4 lower bits are set, the speed value is invalid
+ */
+#define INVALID_SPEED_MASK  (0x0f)
+
+static mutex_t locks[I2C_NUMOF];
+
+static inline NRF_TWIM_Type *dev(i2c_t bus)
+{
+    return i2c_config[bus].dev;
+}
+
+static int error(i2c_t bus)
+{
+    DEBUG("[i2c] error 0x%02x\n", (int)dev(bus)->ERRORSRC);
+    dev(bus)->ERRORSRC = 0;
+    dev(bus)->EVENTS_ERROR = 0;
+    return -1;
+}
+
+static int write(i2c_t bus, uint8_t address, const void *data, int length, int stop)
+{
+    uint8_t *out_buf = (uint8_t *)data;
+    assert((bus <= I2C_NUMOF) && (length > 0));
+
+    DEBUG("[i2c]: writing %i bytes to the bus\n", length);
+
+    /* disable shortcuts */
+    if (stop == 0) {
+        dev(bus)->SHORTS = 0;
+    }
+
+    /* set the client address and the data pointer */
+    dev(bus)->ADDRESS = (address & 0x7f);
+    dev(bus)->TXD.PTR = (uint32_t)out_buf;
+    dev(bus)->TXD.MAXCNT = (length << TWIM_TXD_MAXCNT_MAXCNT_Pos);
+
+    /* start write sequence */
+    dev(bus)->EVENTS_LASTTX = 0;
+    dev(bus)->TASKS_STARTTX = 1;
+
+    /* wait for the device to finish up */
+    while ((dev(bus)->EVENTS_LASTTX == 0) && (dev(bus)->EVENTS_ERROR == 0)) {}
+    if (dev(bus)->EVENTS_ERROR) {
+        return error(bus);
+    }
+
+    /* wait for the device to finish up */
+    while ((dev(bus)->TXD.AMOUNT != (unsigned)length) && (dev(bus)->EVENTS_ERROR == 0)) {}
+    if (dev(bus)->EVENTS_ERROR) {
+        return error(bus);
+    }
+
+    /* enable shortcuts */
+    if (stop == 0) {
+        dev(bus)->SHORTS = (TWIM_SHORTS_LASTTX_STOP_Enabled << TWIM_SHORTS_LASTTX_STOP_Pos) |
+                           (TWIM_SHORTS_LASTRX_STOP_Enabled << TWIM_SHORTS_LASTRX_STOP_Pos);
+    }
+
+    return dev(bus)->TXD.AMOUNT;
+}
+
+int i2c_init_master(i2c_t bus, i2c_speed_t speed)
+{
+    if (bus >= I2C_NUMOF) {
+        return -1;
+    }
+    if (speed & INVALID_SPEED_MASK) {
+        return -2;
+    }
+
+    /* initialize lock */
+    mutex_init(&locks[bus]);
+
+    /* pin configuration */
+    NRF_P0->PIN_CNF[i2c_config[bus].pin_scl] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos);
+    NRF_P0->PIN_CNF[i2c_config[bus].pin_scl] = (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos);
+    dev(bus)->PSEL.SCL = i2c_config[bus].pin_scl;
+    dev(bus)->PSEL.SDA = i2c_config[bus].pin_sda;
+
+    /* shortcuts configuration */
+    dev(bus)->SHORTS = (TWIM_SHORTS_LASTTX_STOP_Enabled << TWIM_SHORTS_LASTTX_STOP_Pos) |
+                       (TWIM_SHORTS_LASTRX_STOP_Enabled << TWIM_SHORTS_LASTRX_STOP_Pos);
+
+    /* bus clock speed configuration */
+    dev(bus)->FREQUENCY = (speed << TWIM_FREQUENCY_FREQUENCY_Pos);
+
+    /* enable the device */
+    dev(bus)->ENABLE = (TWIM_ENABLE_ENABLE_Enabled << TWIM_ENABLE_ENABLE_Pos);
+
+    return 0;
+}
+
+int i2c_acquire(i2c_t bus)
+{
+    assert(bus <= I2C_NUMOF);
+    mutex_lock(&locks[bus]);
+    return 0;
+}
+
+int i2c_release(i2c_t bus)
+{
+    assert(bus <= I2C_NUMOF);
+    mutex_unlock(&locks[bus]);
+    return 0;
+}
+
+int i2c_read_byte(i2c_t bus, uint8_t address, void *data)
+{
+    return i2c_read_bytes(bus, address, data, 1);
+}
+
+int i2c_read_bytes(i2c_t bus, uint8_t address, void *data, int length)
+{
+    uint8_t *in_buf = (uint8_t *)data;
+    assert((bus <= I2C_NUMOF) && (length > 0));
+
+    DEBUG("[i2c] reading %i bytes from the bus\n", length);
+
+    /* set the client address and the data pointer */
+    dev(bus)->ADDRESS = (address & 0x7f);
+    dev(bus)->RXD.PTR = (uint32_t)in_buf;
+    dev(bus)->RXD.MAXCNT = (length << TWIM_RXD_MAXCNT_MAXCNT_Pos);
+
+    /* start read sequence */
+    dev(bus)->EVENTS_STOPPED = 0;
+    dev(bus)->TASKS_STARTRX = 1;
+
+    /* wait for the device to finish up */
+    while ((dev(bus)->EVENTS_STOPPED == 0) && (dev(bus)->EVENTS_ERROR == 0)) {}
+    if (dev(bus)->EVENTS_ERROR) {
+        return error(bus);
+    }
+
+    return dev(bus)->RXD.AMOUNT;
+}
+
+int i2c_read_reg(i2c_t bus, uint8_t address, uint8_t reg, void *data)
+{
+    write(bus, address, &reg, 1, 0);
+    return i2c_read_bytes(bus, address, data, 1);
+}
+
+int i2c_read_regs(i2c_t bus, uint8_t address, uint8_t reg,
+                  void *data, int length)
+{
+    write(bus, address, &reg, 1, 0);
+    return i2c_read_bytes(bus, address, data, length);
+}
+
+int i2c_write_byte(i2c_t bus, uint8_t address, uint8_t data)
+{
+    return write(bus, address, &data, 1, 1);
+}
+
+int i2c_write_bytes(i2c_t bus, uint8_t address, const void *data, int length)
+{
+    return write(bus, address, data, length, 1);
+}
+
+int i2c_write_reg(i2c_t bus, uint8_t address, uint8_t reg, uint8_t data)
+{
+    /* send reg and data in one function call */
+    uint8_t out_buf[2];
+    out_buf[0] = reg;
+    out_buf[1] = data;
+    return write(bus, address, &out_buf, 2, 1) - 1;
+}
+
+int i2c_write_regs(i2c_t bus, uint8_t address, uint8_t reg, const void *data, int length)
+{
+    /* send reg and data in one function call */
+    uint8_t *buf = (uint8_t *)data;
+    uint8_t out_buf[length + 1];
+    out_buf[0] = reg;
+    for (int i = 0; i < length ; i++) {
+        out_buf[i + 1] = buf[i];
+    }
+    return write(bus, address, &out_buf, (length + 1), 1) - 1;
+}