The At24cxx is a family of Serial EEPROM utilizing an I2C (2-wire) serial interface.
This implementation supports the following devices:
Important: I2C pins for the ESP32 must be properly setup the before creating the I2cDevice. For this, make sure you install the nanoFramework.Hardware.Esp32 NuGet and use the Configuration class to configure the pins:
// When connecting with an ESP32 device you will need to configure the I2C GPIOs used for the bus.
Configuration.SetPinFunction(Gpio.IO21, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO22, DeviceFunction.I2C1_CLOCK);For other devices like STM32, please make sure you're using the preset pins for the I2C bus you want to use.
using Iot.Device.At24cxx;
using nanoFramework.Hardware.Esp32;
using System.Device.I2c;
using System.Diagnostics;
using System.Text;
using System.Threading;
// Setup ESP32 I2C port.
Configuration.SetPinFunction(Gpio.IO21, DeviceFunction.I2C1_DATA);
Configuration.SetPinFunction(Gpio.IO22, DeviceFunction.I2C1_CLOCK);
// Setup At24c32c device.
I2cConnectionSettings settings = new I2cConnectionSettings(1, At24c32.DefaultI2cAddress);
I2cDevice i2cDevice = new I2cDevice(settings);
At24c32 eeprom = new At24c32(i2cDevice);
// Write string to device.
string message = "Hello from nanoFramework!";
byte[] encodedMessage = Encoding.UTF8.GetBytes(message);
int messageAddress = 0x0;
uint writeResult = eeprom.Write(messageAddress, encodedMessage);
Debug.WriteLine($"\"{message}\" written to EEPROM at 0x{messageAddress:X} ({writeResult} bytes)");
Thread.Sleep(100);
// Read back message from device.
byte[] receivedData = eeprom.Read(messageAddress, message.Length);
string decodedMessage = Encoding.UTF8.GetString(receivedData, 0, receivedData.Length);
Debug.WriteLine($"\"{decodedMessage}\" read from EEPROM at 0x{messageAddress:X}");
Thread.Sleep(100);
// Write byte to end of available device memory.
byte value = 0xA9;
int byteAddress = eeprom.Size - 1;
uint writeByteResult = eeprom.WriteByte(byteAddress, value);
Debug.WriteLine($"0x{value:X} written to EEPROM at 0x{byteAddress:X} ({writeByteResult} byte)");
Thread.Sleep(100);
// Read back byte from end of available device memory.
byte receivedByte = eeprom.ReadByte(byteAddress);
Debug.WriteLine($"0x{receivedByte:X} read from EEPROM at 0x{byteAddress:X}");
Thread.Sleep(100);
// Sequentially read back message from device byte-by-byte using the devices internal address counter.
// Since our last read from the device was at its last available byte, the internal address counter has now rolled over to point at the first byte.
byte[] receivedCharacter = new byte[1];
for (int i = 0; i < message.Length; i++)
{
receivedCharacter[0] = eeprom.ReadByte();
char[] character = Encoding.UTF8.GetChars(receivedCharacter, 0, 1);
Debug.WriteLine($"'{character[0]}' read from EEPROM");
}