Merge pull request #6117 from u-blox/i2c_read_write

UBLOX C030: I2C avoid any RTOS waits

Author: 0xc0170

targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F437xG/TARGET_UBLOX_C030/battery_charger_i2c.cpp

@@ -0,0 +1,73 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2017 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 "min_battery_voltage.h"
+
+/** Defining HAL_MspInit strong function
+ * in user defined file as described in documentation
+ */
+
+void HAL_MspInit(void)
+{
+    set_minimum_battery_voltage();
+}
+
+void set_minimum_battery_voltage()
+{
+    i2c_t i2c_obj;
+    int data_read;
+    i2c_frequency(&i2c_obj, I2C_FREQUENCY);
+    i2c_init(&i2c_obj, I2C_SDA_B, I2C_SCL_B);
+
+    if (read_from_i2c(BQ24295_I2C_ADDRESS, 0, &data_read, i2c_obj)) {
+        data_read = data_read & MIN_BATTERY_VOLTAGE_MASK;
+        write_to_i2c(BQ24295_I2C_ADDRESS, 0, data_read, i2c_obj);
+            //Battery Voltage is set to 3880mV
+    } else {
+        // Minimum battery voltage could not be set.  This is not a critical error, no need to stop execution
+        // It simply means that longer cabling or USB ports with lower output voltages may cause problems.
+    }
+}
+
+char write_to_i2c(int slave_addr, int reg_addr, int data_write, i2c_t i2c_obj)
+{
+    char ret_code = 0;
+    if (!i2c_start(&i2c_obj)) {
+        if ((i2c_byte_write(&i2c_obj, slave_addr << 1) == 1) &&
+            (i2c_byte_write(&i2c_obj, reg_addr) == 1) &&
+            (i2c_byte_write(&i2c_obj,data_write) ==1)) {
+                 ret_code = 1;
+        }
+        i2c_stop(&i2c_obj);
+    }
+    return ret_code;
+}
+
+char read_from_i2c(int slave_addr, int reg_addr, int* data_read, i2c_t i2c_obj)
+{
+    char ret_code = 0;
+    if (!i2c_start(&i2c_obj)) {
+        if ((i2c_byte_write(&i2c_obj,(slave_addr << 1))==1) &&
+            (i2c_byte_write(&i2c_obj, reg_addr)==1) &&
+            (!i2c_start(&i2c_obj)) &&
+            (i2c_byte_write(&i2c_obj, ((slave_addr << 1) | 0x01)) == 1)) {
+             *data_read = i2c_byte_read(&i2c_obj,1);
+             ret_code = 1;
+        }
+        i2c_stop(&i2c_obj);
+    }
+    return ret_code;
+}

targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F437xG/TARGET_UBLOX_C030/battery_charger_i2c.h

@@ -17,18 +17,23 @@
 #ifndef MIN_BATTERY_VOLTAGE_H
 #define MIN_BATTERY_VOLTAGE_H
 
+#include "hal/i2c_api.h"
+
 #ifdef __cplusplus
 extern"C"{
 #endif
 
-#define BQ24295_I2C_ADDRESS (0x6B << 1)
+#define BQ24295_I2C_ADDRESS (0x6B)
+#define I2C_FREQUENCY 100000
 #define MIN_BATTERY_VOLTAGE_MASK (0x87)
 
 /** Initializes an instance of class BatteryChargerI2c which is using the STM HAL I2C APIs
  *  This allows longer USB cables or USB ports with lower output voltages to power the board correctly.
  */
 
 void set_minimum_battery_voltage(void);
+char read_from_i2c(int slave_addr, int reg_addr, int* data_read, i2c_t i2c_obj);
+char write_to_i2c(int slave_addr, int reg_addr,int data_write, i2c_t i2c_obj);
 
 #ifdef __cplusplus
 }