/// <summary>
/// Create a PwmChannel using a chip and channel.
/// </summary>
/// <remarks>Gpio pin 18 is on chip 0 and channel 0</remarks>
public PwmChannel(int chip, int channel)
{
disposed = true;
var chipPath = $"/sys/class/pwm/pwmchip{chip}";
if (!Directory.Exists(chipPath))
{
throw new IOException($"Could not locate directory {chipPath}.");
}
var channelPath = $"{chipPath}/pwm{channel}";
if (!Directory.Exists(channelPath))
{
Write($"{chipPath}/export", channel.ToString());
Pi.Wait(100);
}
if (!Directory.Exists(channelPath))
{
throw new IOException($"Could not locate directory {channelPath}.");
}
var e = $"{channelPath}/enable";
var p = $"{channelPath}/period";
var d = $"{channelPath}/duty_cycle";
if (!File.Exists(e))
{
throw new IOException($"File {e} does not exist.");
}
if (!File.Exists(p))
{
throw new IOException($"File {p} does not exist.");
}
if (!File.Exists(d))
{
throw new IOException($"File {d} does not exist.");
}
enableFile = new UnixFile(e, "w");
periodFile = new UnixFile(p, "w");
dutyCycleFile = new UnixFile(d, "w");
disposed = false;
}
static void Write(UnixFile file, string text)
{
file.Reset();
file.Write(text);
}
static void Write(string fileName, string text)
{
using (var file = new UnixFile(fileName))
file.Write(text);
}