Add Eight-Bit-Adressing mode to I2CEEBlockDevice.

When dealing with EEPROMs without a 16 bit adressing, the current
implementation does not work, as it writes a 16 bit address to the chip.
This may cause undefined behaviour.
This change adds a new constructor argument to enable this new eight-bit
mode. It defaults to false to not break existing code.
This constructor argument should actually never be necessary to manually
set, except when dealing with cheap devices.

Author: boomer41

components/storage/blockdevice/COMPONENT_I2CEE/I2CEEBlockDevice.cpp

@@ -22,17 +22,21 @@ using namespace mbed;
 
 I2CEEBlockDevice::I2CEEBlockDevice(
     PinName sda, PinName scl, uint8_t addr,
-    bd_size_t size, bd_size_t block, int freq)
-    : _i2c_addr(addr), _size(size), _block(block)
+    bd_size_t size, bd_size_t block, int freq,
+    bool address_is_eight_bit)
+    : _i2c_addr(addr), _size(size), _block(block),
+      _address_is_eight_bit(address_is_eight_bit)
 {
     _i2c = new (_i2c_buffer) I2C(sda, scl);
     _i2c->frequency(freq);
 }
 
 I2CEEBlockDevice::I2CEEBlockDevice(
     I2C *i2c_obj, uint8_t addr,
-    bd_size_t size, bd_size_t block)
-    : _i2c_addr(addr), _size(size), _block(block)
+    bd_size_t size, bd_size_t block,
+    bool address_is_eight_bit)
+    : _i2c_addr(addr), _size(size), _block(block),
+      _address_is_eight_bit(address_is_eight_bit)
 {
     _i2c = i2c_obj;
 }
@@ -60,9 +64,15 @@ int I2CEEBlockDevice::read(void *buffer, bd_addr_t addr, bd_size_t size)
 
     _i2c->start();
 
-    if (!_i2c->write(_i2c_addr | 0) ||
-            !_i2c->write((char)(addr >> 8)) ||
-            !_i2c->write((char)(addr & 0xff))) {
+    if (!_i2c->write(_i2c_addr | 0)) {
+        return BD_ERROR_DEVICE_ERROR;
+    }
+
+    if (!_address_is_eight_bit && !_i2c->write((char)(addr >> 8))) {
+        return BD_ERROR_DEVICE_ERROR;
+    }
+
+    if (!_i2c->write((char)(addr & 0xff))) {
         return BD_ERROR_DEVICE_ERROR;
     }
 
@@ -92,9 +102,15 @@ int I2CEEBlockDevice::program(const void *buffer, bd_addr_t addr, bd_size_t size
 
         _i2c->start();
 
-        if (!_i2c->write(_i2c_addr | 0) ||
-                !_i2c->write((char)(addr >> 8)) ||
-                !_i2c->write((char)(addr & 0xff))) {
+        if (!_i2c->write(_i2c_addr | 0)) {
+            return BD_ERROR_DEVICE_ERROR;
+        }
+
+        if (!_address_is_eight_bit && !_i2c->write((char)(addr >> 8))) {
+            return BD_ERROR_DEVICE_ERROR;
+        }
+
+        if (!_i2c->write((char)(addr & 0xff))) {
             return BD_ERROR_DEVICE_ERROR;
         }
 

components/storage/blockdevice/COMPONENT_I2CEE/I2CEEBlockDevice.h

@@ -59,29 +59,37 @@ class I2CEEBlockDevice : public BlockDevice {
 public:
     /** Constructor to create an I2CEEBlockDevice on I2C pins
      *
-     *  @param sda      The pin name for the sda line of the I2C bus.
-     *  @param scl      The pin name for the scl line of the I2C bus.
-     *  @param addr     The 8bit I2C address of the chip, common range 0xa0 - 0xae.
-     *  @param size     The size of the device in bytes
-     *  @param block    The page size of the device in bytes, defaults to 32bytes
-     *  @param freq     The frequency of the I2C bus, defaults to 400K.
+     *  @param sda                  The pin name for the sda line of the I2C bus.
+     *  @param scl                  The pin name for the scl line of the I2C bus.
+     *  @param addr                 The 8bit I2C address of the chip, common range 0xa0 - 0xae.
+     *  @param size                 The size of the device in bytes
+     *  @param block                The page size of the device in bytes, defaults to 32bytes
+     *  @param freq                 The frequency of the I2C bus, defaults to 400K.
+     *  @param address_is_eight_bit Specifies whether the EEPROM device is using eight bit
+     *                              addresses instead of 16 bit addresses. This should not be needed
+     *                              unless dealing with very cheap devices.
      */
     I2CEEBlockDevice(
         PinName sda, PinName scl, uint8_t address,
         bd_size_t size, bd_size_t block = 32,
-        int bus_speed = 400000);
+        int bus_speed = 400000,
+        bool address_is_eight_bit = false);
 
     /** Constructor to create an I2CEEBlockDevice on I2C pins
-    *
-    *  @param i2c      The I2C instance pointer
-    *  @param addr     The 8bit I2C address of the chip, common range 0xa0 - 0xae.
-    *  @param size     The size of the device in bytes
-    *  @param block    The page size of the device in bytes, defaults to 32bytes
-    *  @param freq     The frequency of the I2C bus, defaults to 400K.
-    */
+     *
+     *  @param i2c                  The I2C instance pointer
+     *  @param addr                 The 8bit I2C address of the chip, common range 0xa0 - 0xae.
+     *  @param size                 The size of the device in bytes
+     *  @param block                The page size of the device in bytes, defaults to 32bytes
+     *  @param freq                 The frequency of the I2C bus, defaults to 400K.
+     *  @param address_is_eight_bit Specifies whether the EEPROM device is using eight bit
+     *                              addresses instead of 16 bit addresses. This should not be needed
+     *                              unless dealing with very cheap devices.
+     */
     I2CEEBlockDevice(
         mbed::I2C *i2c_obj, uint8_t address,
-        bd_size_t size, bd_size_t block = 32);
+        bd_size_t size, bd_size_t block = 32,
+        bool address_is_eight_bit = false);
 
     /** Destructor of I2CEEBlockDevice
      */
@@ -169,6 +177,8 @@ class I2CEEBlockDevice : public BlockDevice {
     uint32_t _size;
     uint32_t _block;
 
+    bool _address_is_eight_bit;
+
     int _sync();
 };