Apa102

APA102 - Double line transmission integrated control LED

APA102 is a intelligent control LED light source that the control circuit and RGB chip are integrated in a package of 5050/2020 components. It internal include 3 groups shift register and Selfdetection sign decoder circuit.

It's different from WS2812. In addition to the data line, it has a clock line. So APA102 has no strict requirements for timing. It's more friendly to devices such as Raspberry Pi that can't precisely control the timing of data lines.

There are other models like APA107, HD107s, SK9822, etc. The controls are exactly the same.

Model	SCLK	PWM
APA102	20 MHz	20 kHz
APA107	30 MHz	9 kHz
HD107s	40 MHz	27 kHz
SK9822	15 MHz	4.7 kHz

Documentation

• APA102
• SK9822
• Compare SK6822 WS2813 APA102 SK9822 LED
• Difference between APA102, APA107,HD107s and SK9822

Usage

Important: make sure you properly setup the SPI pins especially for ESP32 before creating the SpiDevice, make sure you install the nanoFramework.Hardware.ESP32 nuget:

//////////////////////////////////////////////////////////////////////
// when connecting to an ESP32 device, need to configure the SPI GPIOs
// used for the bus
Configuration.SetPinFunction(21, DeviceFunction.SPI1_MOSI);
Configuration.SetPinFunction(22, DeviceFunction.SPI1_MISO);
Configuration.SetPinFunction(23, DeviceFunction.SPI1_CLOCK);
// Make sure as well you are using the right chip select

For other devices like STM32, please make sure you're using the pre-set pins for the SPI bus you want to use. The chip select can as well be pre setup.

Here is an example how to use the APA102:

using System;
using System.Device.Spi;
using System.Drawing;
using System.Threading;
using Iot.Device.Apa102;

var random = new Random();

using SpiDevice spiDevice = SpiDevice.Create(new SpiConnectionSettings(1, 42)
{
    ClockFrequency = 20_000_000,
    DataFlow = DataFlow.MsbFirst,
    Mode = SpiMode.Mode0 // ensure data is ready at clock rising edge
});
using Apa102 apa102 = new Apa102(spiDevice, 16);

while (true)
{
    for (var i = 0; i < apa102.Pixels.Length; i++)
    {
        apa102.Pixels[i] = Color.FromArgb(255, random.Next(256), random.Next(256), random.Next(256));
    }

    apa102.Flush();
    Thread.Sleep(1000);
}