Diff: targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/i2c_api.c

Revision:

168:9672193075cf

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_ARM_SSG/TARGET_CM3DS_MPS2/i2c_api.c	Thu Jul 06 15:42:05 2017 +0100
@@ -0,0 +1,273 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "i2c_api.h"
+#include "cmsis.h"
+#include "mbed_error.h"
+#include "mbed_wait_api.h"
+#include "SMM_MPS2.h"
+#include "pinmap.h"
+
+/*
+ * The ARM I2C SBCon IP (Two-wire serial bus interface) requires a
+ * bit banging programing model.
+ */
+
+#if DEVICE_I2CSLAVE
+#error "I2C slave is not supported in MPS2 CM3DS board"
+#endif
+
+#define DEFAULT_I2C_SBCON_HZ   4000000U /* 4MHz */
+#define STOP_REQUIRED          1
+#define LAST_ACK_REQUIRED      1
+#define LAST_ACK_NOT_REQUIRED  0
+#define I2C_ACK_BIT            0x1
+
+#define SDA  (1 << 1)
+#define SCL  (1 << 0)
+#define I2C_HIGH(p_i2c, pin) (p_i2c->CONTROLS = pin)
+#define I2C_LOW(p_i2c, pin)  (p_i2c->CONTROLC = pin)
+#define I2C_GET(p_i2c, pin)  ((p_i2c->CONTROL >> (pin-1)) & 0x01)
+
+static const PinMap PinMap_I2C_SDA[] = {
+    {TSC_SDA      , I2C_0, 0},
+    {AUD_SDA      , I2C_1, 0},
+    {SHIELD_0_SDA , I2C_2, ALTERNATE_FUNC},
+    {SHIELD_1_SDA , I2C_3, ALTERNATE_FUNC},
+    {NC           , NC   , 0}
+};
+
+static const PinMap PinMap_I2C_SCL[] = {
+    {TSC_SCL      , I2C_0, 0},
+    {AUD_SCL      , I2C_1, 0},
+    {SHIELD_0_SCL , I2C_2, ALTERNATE_FUNC},
+    {SHIELD_1_SCL , I2C_3, ALTERNATE_FUNC},
+    {NC           , NC,    0}
+};
+
+/*
+ * \brief Transmits a data bit.
+ *
+ * \param[in] obj  I2C object
+ * \param[in] bit  Bit to transmit
+ */
+static void i2c_tx_bit(i2c_t *obj, uint8_t bit)
+{
+    if (bit != 0) {
+        I2C_HIGH(obj->i2c, SDA);
+    } else {
+        I2C_LOW(obj->i2c, SDA);
+    }
+
+    wait_us(obj->freq_us);
+
+    I2C_HIGH(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+
+    I2C_LOW(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+}
+
+/*
+ * \brief Reads a data bit
+ *
+ * \param[in] obj  I2C object
+ *
+ * \returns Bit value received.
+ */
+static uint8_t i2c_rx_bit(i2c_t *obj)
+{
+    uint8_t bit;
+
+    I2C_HIGH(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+
+    I2C_HIGH(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+
+    bit = I2C_GET(obj->i2c, SDA);
+
+    I2C_LOW(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+
+    return bit;
+}
+
+void i2c_init(i2c_t *obj, PinName sda, PinName scl)
+{
+    I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
+    I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
+    obj->i2c = (MPS2_I2C_TypeDef *)pinmap_merge(i2c_sda, i2c_scl);
+
+    if ((int)obj->i2c == NC) {
+        error("I2C pin mapping failed");
+    }
+
+    switch ((int)obj->i2c) {
+        case I2C_2:
+        case I2C_3:
+            /* Enables alt-function to use I2C SCL and SDA signals */
+            pin_function(sda, ALTERNATE_FUNC);
+            pin_function(scl, ALTERNATE_FUNC);
+            break;
+       default:
+            break;
+    }
+
+    /* Sets default I2C frequency in microseconds */
+    obj->freq_us = (SystemCoreClock / DEFAULT_I2C_SBCON_HZ);
+}
+
+void i2c_frequency(i2c_t *obj, int hz)
+{
+    if ((hz <= 0) || ((unsigned int)hz > SystemCoreClock)) {
+        error("Couldn't setup requested I2C frequency %dHz", hz);
+    }
+
+    obj->freq_us = (SystemCoreClock / hz);
+}
+
+int i2c_start(i2c_t *obj)
+{
+    I2C_HIGH(obj->i2c, (SCL | SDA));
+    wait_us(obj->freq_us);
+
+    I2C_LOW(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+
+    I2C_LOW(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+
+    return 0;
+}
+
+int i2c_stop(i2c_t *obj)
+{
+    I2C_LOW(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+
+    I2C_HIGH(obj->i2c, SCL);
+    wait_us(obj->freq_us);
+
+    I2C_HIGH(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+
+    return 0;
+}
+
+int i2c_read(i2c_t *obj, int address, char *data, int length, int stop)
+{
+    int32_t nbr_bytes_read = 0;
+
+    if (data == 0 || length == 0) {
+        error("Invalid i2c_read input data");
+    }
+
+    i2c_start(obj);
+
+    i2c_byte_write(obj, (uint8_t)(address | 0x1));
+
+    while(nbr_bytes_read < (length - 1)) {
+        data[nbr_bytes_read++] = i2c_byte_read(obj, LAST_ACK_NOT_REQUIRED);
+    }
+
+    data[nbr_bytes_read++] = i2c_byte_read(obj, LAST_ACK_REQUIRED);
+
+    if (stop == STOP_REQUIRED) {
+        i2c_stop(obj);
+    }
+
+    return nbr_bytes_read;
+}
+
+int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
+{
+    int32_t nbr_bytes_write;
+
+    if (data == 0) {
+        error("Invalid i2c_write input data");
+    }
+
+    i2c_start(obj);
+
+    i2c_byte_write(obj, (uint8_t)address);
+
+    for (nbr_bytes_write = 0; nbr_bytes_write < length; nbr_bytes_write++) {
+        i2c_byte_write(obj, data[nbr_bytes_write]);
+    }
+
+    if (stop == STOP_REQUIRED) {
+       i2c_stop(obj);
+    }
+
+    return nbr_bytes_write;
+}
+
+void i2c_reset(i2c_t *obj)
+{
+   uint32_t iter;
+
+    /*
+     * The reset sequence is:
+     *  - SDA line low
+     *  - 9 clock pulses
+     *  - SDA line high
+     */
+    I2C_LOW(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+
+    for(iter=0; iter < 9; iter++) {
+        I2C_LOW(obj->i2c, SCL);
+        wait_us(obj->freq_us);
+        I2C_HIGH(obj->i2c, SCL);
+        wait_us(obj->freq_us);
+    }
+
+    I2C_HIGH(obj->i2c, SDA);
+    wait_us(obj->freq_us);
+}
+
+int i2c_byte_read(i2c_t *obj, int last)
+{
+    uint8_t nbr_bits;
+    uint8_t data = 0;
+
+    data = i2c_rx_bit(obj);
+    for (nbr_bits = 1; nbr_bits < 8; nbr_bits++) {
+        data <<= 1;
+        data |= i2c_rx_bit(obj);
+    }
+
+    i2c_tx_bit(obj, last);
+
+    return data;
+}
+
+int i2c_byte_write(i2c_t *obj, int data)
+{
+    uint8_t nbr_bits;
+    uint8_t ack;
+
+    for(nbr_bits=0; nbr_bits < 7; nbr_bits++) {
+        i2c_tx_bit(obj, data & 0x80);
+        data <<= 1;
+    }
+
+    i2c_tx_bit(obj, data & 0x80);
+
+    ack = i2c_rx_bit(obj);
+
+    return ack;
+}