private void Send4Bits(byte control, byte d)
{
byte portB = control;
portB |= FlipAndShift(d);
portB |= ENABLE_BIT;
if (register == Register.GPIOA)
{
expander.Write(MCP23017.Register.GPIOA, portB);
}
else
{
expander.Write(MCP23017.Register.GPIOB, portB);
}
portB &= 0xDF;
if (register == Register.GPIOA)
{
expander.Write(MCP23017.Register.GPIOA, portB);
}
else
{
expander.Write(MCP23017.Register.GPIOB, portB);
}
}
public HD44780U(MCP23017 exp, Register reg)
{
expander = exp;
register = reg;
if (register == Register.GPIOA)
{
expander.Write(MCP23017.Register.IODIRA, 0x00);
expander.Write(MCP23017.Register.GPIOA, 0x00);
}
else
{
expander.Write(MCP23017.Register.IODIRB, 0x00);
expander.Write(MCP23017.Register.GPIOB, 0x00);
}
}
public double GetDistance(Units toUnits)
{
double results = 0;
TimeSpan elapsedTime;
Stopwatch sw = new Stopwatch();
Stopwatch sw2 = new Stopwatch();
sw2.Reset();
sw2.Start();
sw.Reset();
long startTicks = 0;
long ticksPerSecond = Stopwatch.Frequency;
//Although the majority of the code between the Raspberry Pi GPIO
//and the expander I/O will be the same I am separating them to
//reduce any additional operations which could alter the timings
if (expander == null)
{
rpTriggerPin.SetDriveMode(GpioPinDriveMode.Output);
rpEchoPin.SetDriveMode(GpioPinDriveMode.Input);
//Turn off the trigger
rpTriggerPin.Write(GpioPinValue.Low);
// wait for the sensor to settle
Task.Delay(TimeSpan.FromMilliseconds(500)).Wait();
// turn on the pulse
rpTriggerPin.Write(GpioPinValue.High);
// let the pulse run for 10 microseconds
Task.Delay(TimeSpan.FromMilliseconds(.01)).Wait();
// turn off the pulse
rpTriggerPin.Write(GpioPinValue.Low);
// start the stopwatch just as the echo starts
startTicks = sw2.ElapsedTicks;
while (rpEchoPin.Read() == GpioPinValue.Low && sw2.ElapsedTicks - startTicks < ticksPerSecond)
{
;
}
sw.Start();
// stop the stopwatch when the echo stops
startTicks = sw2.ElapsedTicks;
while (rpEchoPin.Read() == GpioPinValue.High && sw2.ElapsedTicks - startTicks < ticksPerSecond)
{
;
}
sw.Stop();
// the duration of the echo is equal to the pulse's roundtrip time
elapsedTime = sw.Elapsed;
}
else
{
expander.SetDriveMode(ioTriggerPin, MCP23017.PinMode.Ouput);
expander.SetDriveMode(ioEchoPin, MCP23017.PinMode.Input);
// turn off the trigger
expander.Write(ioTriggerPin, MCP23017.PinValue.Low);
// wait for the sensor to settle
Task.Delay(TimeSpan.FromMilliseconds(500)).Wait();
// turn on the pulse
expander.Write(ioTriggerPin, MCP23017.PinValue.High);
// let the pulse run for 10 microseconds
Task.Delay(TimeSpan.FromMilliseconds(.01)).Wait();
// turn off the pulse
expander.Write(ioTriggerPin, MCP23017.PinValue.Low);
startTicks = sw2.ElapsedTicks;
// start the stopwatch just as the echo starts
while (expander.Read(ioEchoPin) == false && sw2.ElapsedTicks - startTicks < ticksPerSecond)
{
;
}
sw.Start();
// stop the stopwatch when the echo stops
startTicks = sw2.ElapsedTicks;
while (expander.Read(ioEchoPin) == true && sw2.ElapsedTicks - startTicks < ticksPerSecond)
{
;
}
sw.Stop();
// the duration of the echo is equal to the pulse's roundtrip time
elapsedTime = sw.Elapsed;
}
/*Convert value to proper units
* Speed of sound at ground level in air
* 13.51 inches per second
* 1.126 ft per second
* 34.32 centimeters per second
* 343.2 millimeters per second
*/
//Since the sound is sent out and bounces back we need
//to take the elapsed time in milliseconds and divide it by 2
results = elapsedTime.TotalMilliseconds / 2;
switch (toUnits)
{
case Units.Centimeters:
results = results * 34.32;
break;
case Units.Millimeters:
results = results * 343.2;
break;
case Units.Feet:
results = results * 1.126;
break;
case Units.Inches:
results = results * 13.51;
break;
}
return(results);
}
