I2C

I2C (pronounced eye-squared-sea or eye-two-sea) is a synchronous two-wire serial bus. One master shares the bus with one or more slaves; each slave is selected by a 7-bit address sent on the bus instead of by a dedicated chip-select line. The two wires are SDA (Serial Data) and SCL (Serial Clock).

Endpoint uses the standard System.Device.I2c API for the data transfer. The only Endpoint-specific step is calling I2cController.Initialize(bus) first, which claims the bus's pins and sets the clock speed. The default speed is 400 kHz; pass a second argument to change it.

.NET

using System.Device.I2c;
using GHIElectronics.Endpoint.Core;

// Bring up I2C6 at the default 400 kHz
I2cController.Initialize(EPDomino24.I2c.I2c6);

// Open the device and talk to it with the standard API
var settings = new I2cConnectionSettings(EPDomino24.I2c.I2c6, deviceAddress: 0x1C);
using var i2c = I2cDevice.Create(settings);

// Write a byte to a register
i2c.Write(new byte[] { 0x2A, 0x01 });

// Read a register (write the register address, then read the value)
var read = new byte[1];
i2c.WriteRead(new byte[] { 0x2A }, read);
Console.WriteLine($"0x2A = {read[0]:X2}");

Python

from GHIElectronics.Endpoint.Core import EPDomino24, I2cController
from GHIElectronics.Endpoint.Devices.I2c import I2cDevice, I2cConnectionSettings

# Bring up I2C6 at the default 400 kHz
I2cController.Initialize(EPDomino24.I2c.I2c6)

# Open the device and talk to it with the standard API
settings = I2cConnectionSettings(EPDomino24.I2c.I2c6, 0x1C)
with I2cDevice.Create(settings) as i2c:
    # Write a byte to a register
    i2c.Write(bytes([0x2A, 0x01]))

    # Read a register (write the register address, then read the value)
    read = bytearray(1)
    i2c.WriteRead(bytes([0x2A]), read)
    print(f"0x2A = {read[0]:02X}")

C/C++

#include <array>
#include <cstdint>
#include <cstdio>
#include <endpoint/I2cController.h>
#include <endpoint/EPDomino24.h>

using namespace GHIElectronics::Endpoint::Core;
using namespace GHIElectronics::Endpoint::Devices::I2c;

// Bring up I2C6 at the default 400 kHz
I2cController::Initialize(EPDomino24::I2c::I2c6);

// Open the device and talk to it with the standard API
auto i2c = I2cDevice::Create(I2cConnectionSettings(EPDomino24::I2c::I2c6, 0x1C));

// Write a byte to a register
i2c.Write(std::array<uint8_t, 2>{0x2A, 0x01});

// Read a register (write the register address, then read the value)
std::array<uint8_t, 1> read{};
i2c.WriteRead(std::array<uint8_t, 1>{0x2A}, read);
std::printf("0x2A = %02X\n", read[0]);

Change the clock speed if the device needs it:

.NET

I2cController.Initialize(EPDomino24.I2c.I2c6, frequency: 100_000);   // 100 kHz

Python

I2cController.Initialize(EPDomino24.I2c.I2c6, 100_000)   # 100 kHz

C/C++

I2cController::Initialize(EPDomino24::I2c::I2c6, 100'000);   // 100 kHz

tip

I2cController is chip-neutral; the same call works on any supported module. The bus constant (EPDomino24.I2c.I2c6) is board-specific and lists only the buses actually bonded on EP-Domino24.