Abstraction of I2C interface for discussion - STM32

src/ArduinoInterface.h

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+/*
+ * Copyright (C) 2020 Bruce MacKinnon KC1FSZ
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _ArduinoInterface_h
+#define _ArduinoInterface_h
+
+#include "Arduino.h"
+#include "Wire.h"
+#include "I2CInterface.h"
+
+/**
+ * The standard Ardiuno way of talking to I2C
+ * via the Wire.h library.
+ */
+class ArduinoInterface : public I2CInterface {
+public:
+
+    ArduinoInterface() {
+        Wire.begin();
+    }
+
+    uint8_t check_address(uint8_t i2c_bus_addr) {
+    	Wire.beginTransmission(i2c_bus_addr);
+        return Wire.endTransmission();
+    }
+
+    uint8_t read(uint8_t i2c_bus_addr, uint8_t addr) {
+
+        uint8_t reg_val = 0;
+
+        Wire.beginTransmission(i2c_bus_addr);
+        Wire.write(addr);
+        Wire.endTransmission();
+
+        Wire.requestFrom(i2c_bus_addr, (uint8_t)1, (uint8_t)false);
+
+        while(Wire.available())
+        {
+            reg_val = Wire.read();
+        }
+
+        return reg_val;
+    }
+
+    uint8_t write(uint8_t i2c_bus_addr, uint8_t addr, uint8_t data) {
+    	Wire.beginTransmission(i2c_bus_addr);
+        Wire.write(addr);
+        Wire.write(data);
+        return Wire.endTransmission();
+    }
+
+    uint8_t write_bulk(uint8_t i2c_bus_addr, uint8_t addr, uint8_t bytes, uint8_t *data) {
+        Wire.beginTransmission(i2c_bus_addr);
+        Wire.write(addr);
+        for(int i = 0; i < bytes; i++)
+        {
+            Wire.write(data[i]);
+        }
+        return Wire.endTransmission();
+     }
+};
+
+#endif

src/I2CInterface.h

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+/*
+ * Copyright (C) 2020 Bruce MacKinnon KC1FSZ
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _I2CInterface_h
+#define _I2CInterface_h
+
+#include <stdint.h>
+
+/**
+ * A generic interface for interacting with an I2C bus
+ */
+class I2CInterface {
+public:
+
+    /**
+     * Determmines whether a device is connected at the specified address.
+     * @return 0 if things are good, -1 if there is a problem.
+     */
+    virtual uint8_t check_address(uint8_t i2c_bus_addr) = 0;
+
+    /**
+     * Standard read operation.
+     * @return The received byte
+     */
+    virtual uint8_t read(uint8_t i2c_bus_addr, uint8_t addr) = 0;
+
+    /** 
+     * Standard write operation.
+     * @return Then number of bytes written
+     */
+    virtual uint8_t write(uint8_t i2c_bus_addr, uint8_t addr, uint8_t data) = 0;
+
+    /**
+     * Multi-byte write operation
+     * @return The number of bytes written
+     */
+    virtual uint8_t write_bulk(uint8_t i2c_bus_addr, uint8_t addr, uint8_t bytes, uint8_t *data) = 0;
+};
+
+#endif

src/STM32_HAL_Interface.h

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+/*
+ * Copyright (C) 2020 Bruce MacKinnon KC1FSZ
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _STM32_HAL_Interface_h
+#define _STM32_HAL_Interface_h
+
+#include <stdint.h>
+// NOTE: Add the appropriate HAL include here:
+#include "stm32f4xx_hal.h"
+
+#include "I2CInterface.h"
+
+// An STM32/HAL based implementation of the I2CInterface.
+// 
+// NOT IMPLEMENTED YET!!
+//
+class STM32_HAL_Interface : public I2CInterface {
+public:
+
+    STM32_HAL_Interface(I2C_HandleTypeDef* hi2c)
+    :   _hi2c(hi2c),
+        _errorCount(0),
+        _timeoutMs(10) {
+    }
+
+    uint8_t check_address(uint8_t i2c_bus_addr) {
+        HAL_StatusTypeDef status = HAL_I2C_IsDeviceReady(_hi2c, (uint16_t)(i2c_bus_addr << 1), 1, _timeoutMs);
+        if (status == HAL_OK) {
+           return 0;
+        } else {
+            return -1;
+        }
+    }
+
+    uint8_t read(uint8_t i2c_bus_addr, uint8_t addr) {
+        uint8_t reg_val = 0;
+        // NOTE: PER HAL DOCUMENTATION, ADDRESS NEEDS TO BE SHIFTED LEFT
+        HAL_StatusTypeDef status = HAL_I2C_Mem_Read(_hi2c, (uint16_t)(i2c_bus_addr << 1), (uint16_t)(addr), 1, 
+            &reg_val, 1, _timeoutMs);
+        if (status != HAL_OK) {
+            _errorCount++;
+        }
+        return reg_val;        
+    }
+
+    uint8_t write(uint8_t i2c_bus_addr, uint8_t addr, uint8_t data) {
+        // NOTE: PER HAL DOCUMENTATION, ADDRESS NEEDS TO BE SHIFTED LEFT
+	    HAL_StatusTypeDef status = HAL_I2C_Mem_Write(_hi2c, (uint16_t)(i2c_bus_addr << 1), addr, 1, 
+            &data, 1, _timeoutMs);
+        if (status != HAL_OK) {
+            _errorCount++;
+        }
+        return 1;
+    }
+
+    uint8_t write_bulk(uint8_t i2c_bus_addr, uint8_t addr, uint8_t bytes, uint8_t *data)  {
+        // NOTE: PER HAL DOCUMENTATION, ADDRESS NEEDS TO BE SHIFTED LEFT
+	    HAL_StatusTypeDef status = HAL_I2C_Mem_Write(_hi2c, (uint16_t)(i2c_bus_addr << 1), addr, 1, 
+            data, bytes, _timeoutMs);
+        if (status != HAL_OK) {
+            _errorCount++;
+        }
+        return bytes;
+    }
+
+private:
+
+    I2C_HandleTypeDef* _hi2c;
+    int _errorCount;
+    uint32_t _timeoutMs;
+};
+
+#endif

src/TestInterface.h

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+/*
+ * Copyright (C) 2020 Bruce MacKinnon KC1FSZ
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef _Test_Interface_h
+#define _Test_Interface_h
+
+#include <stdint.h>
+#include <stdio.h>
+#include "I2CInterface.h"
+
+// A dummy interface for testing.
+// 
+class TestInterface : public I2CInterface {
+public:
+    TestInterface() {
+        printf("TestInterface initialized\n");
+    }
+    uint8_t check_address(uint8_t i2c_bus_addr) {
+        printf("check_address\n");
+        return 0;
+    }
+    uint8_t read(uint8_t i2c_bus_addr, uint8_t addr) {
+        printf("read(%x,%x)\n", i2c_bus_addr, addr);
+        return 0;
+    }
+    uint8_t write(uint8_t i2c_bus_addr, uint8_t addr, uint8_t data) {
+        printf("write(%x, %x, %x)\n", i2c_bus_addr, addr, data);
+        return 0;
+    }
+    uint8_t write_bulk(uint8_t i2c_bus_addr, uint8_t addr, uint8_t bytes, uint8_t *data)  {
+        printf("write_bulk(%x, %x, ", i2c_bus_addr, addr);
+        for (int i = 0; i < bytes; i++) {
+            printf("%x ", data[i]);
+        }
+        printf(")\n");
+        return 0;
+    }
+};
+
+#endif