* Added 8-bit I2CEEBlockDevice support (e.g. 24LC04B EEPROM)

  This old patch was lost when fork created

Author: Mads Bligaard Nielsen

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;
 }
@@ -58,43 +62,61 @@ int I2CEEBlockDevice::read(void *buffer, bd_addr_t addr, bd_size_t size)
     // Check the address and size fit onto the chip.
     MBED_ASSERT(is_valid_read(addr, size));
 
+    auto *pBuffer = static_cast<char *>(buffer);
+
     _i2c->start();
 
-    if (!_i2c->write(_i2c_addr | 0) ||
-            !_i2c->write((char)(addr >> 8)) ||
-            !_i2c->write((char)(addr & 0xff))) {
+    if (1 != _i2c->write(get_paged_device_address(addr))) {
+        return BD_ERROR_DEVICE_ERROR;
+    }
+
+    if (!_address_is_eight_bit && 1 != _i2c->write((char)(addr >> 8u))) {
+        return BD_ERROR_DEVICE_ERROR;
+    }
+
+    if (1 != _i2c->write((char)(addr & 0xffu))) {
         return BD_ERROR_DEVICE_ERROR;
     }
 
     _i2c->stop();
 
-    if (_i2c->read(_i2c_addr, static_cast<char *>(buffer), size) < 0) {
+    if (0 != _i2c->read(_i2c_addr, pBuffer, size)) {
         return BD_ERROR_DEVICE_ERROR;
     }
 
-    return 0;
+    return BD_ERROR_OK;
 }
 
 int I2CEEBlockDevice::program(const void *buffer, bd_addr_t addr, bd_size_t size)
 {
     // Check the addr and size fit onto the chip.
     MBED_ASSERT(is_valid_program(addr, size));
 
+    const auto *pBuffer = static_cast<const char *>(buffer);
+
     // While we have some more data to write.
     while (size > 0) {
         uint32_t off = addr % _block;
         uint32_t chunk = (off + size < _block) ? size : (_block - off);
 
         _i2c->start();
 
-        if (!_i2c->write(_i2c_addr | 0) ||
-                !_i2c->write((char)(addr >> 8)) ||
-                !_i2c->write((char)(addr & 0xff))) {
+        if (1 != _i2c->write(get_paged_device_address(addr))) {
+            return BD_ERROR_DEVICE_ERROR;
+        }
+
+        if (!_address_is_eight_bit && 1 != _i2c->write((char)(addr >> 8u))) {
+            return BD_ERROR_DEVICE_ERROR;
+        }
+
+        if (1 != _i2c->write((char)(addr & 0xffu))) {
             return BD_ERROR_DEVICE_ERROR;
         }
 
         for (unsigned i = 0; i < chunk; i++) {
-            _i2c->write(static_cast<const char *>(buffer)[i]);
+            if (1 != _i2c->write(pBuffer[i])) {
+                return BD_ERROR_DEVICE_ERROR;
+            }
         }
 
         _i2c->stop();
@@ -107,10 +129,10 @@ int I2CEEBlockDevice::program(const void *buffer, bd_addr_t addr, bd_size_t size
 
         addr += chunk;
         size -= chunk;
-        buffer = static_cast<const char *>(buffer) + chunk;
+        pBuffer += chunk;
     }
 
-    return 0;
+    return BD_ERROR_OK;
 }
 
 int I2CEEBlockDevice::erase(bd_addr_t addr, bd_size_t size)
@@ -159,3 +181,14 @@ const char *I2CEEBlockDevice::get_type() const
 {
     return "I2CEE";
 }
+
+uint8_t I2CEEBlockDevice::get_paged_device_address(bd_addr_t address)
+{
+    if (!_address_is_eight_bit) {
+        return _i2c_addr;
+    } else {
+        // Use the three least significant bits of the 2nd byte as the page
+        // The page will be bits 2-4 of the user defined addresses.
+        return _i2c_addr | ((address & 0x0700u) >> 7u);
+    }
+}

components/storage/blockdevice/COMPONENT_I2CEE/I2CEEBlockDevice.h

@@ -65,11 +65,15 @@ class I2CEEBlockDevice : public BlockDevice {
      *  @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 is used for example
+     *                              in AT24C series chips.
      */
     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
     *
@@ -78,10 +82,14 @@ class I2CEEBlockDevice : public BlockDevice {
     *  @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 is used for example
+    *                              in AT24C series chips.
     */
     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
      */
@@ -168,8 +176,19 @@ class I2CEEBlockDevice : public BlockDevice {
     uint8_t _i2c_addr;
     uint32_t _size;
     uint32_t _block;
+    bool _address_is_eight_bit;
 
     int _sync();
+
+    /**
+     * Gets the device's I2C address with respect to the requested page.
+     * When eight-bit mode is disabled, this function is a noop.
+     * When eight-bit mode is enabled, it sets the bits required
+     * in the devices address. Other bits remain unchanged.
+     * @param address An address in the requested page.
+     * @return The device's I2C address for that page
+     */
+    uint8_t get_paged_device_address(bd_addr_t address);
 };