public static void Main()
{
var sensor = new HCSR04(Stm32F4Discovery.FreePins.PC2, Stm32F4Discovery.FreePins.PC1);
//crash detect: red led on or off
var crashLed = new OutputPort(Stm32F4Discovery.LedPins.Red, false);
var scanPeriod = new TimeSpan(0, 0, 0, 0, 100);//100ms
var detector = new CollisionDetector(sensor, scanPeriod)
{
Barier = 10
}; //10cm
detector.StateChanged += crashLed.Write;
//pwm frequency display (green led linear blink): far->lo freq, near->hi freq
var distancePwm = new PWM(Cpu.PWMChannel.PWM_0, 1, 0, false);
distancePwm.Start();
//print distance every 1s and change pwm freq
DateTime nextPrint = DateTime.Now;
for (;;)
{
TimeSpan pulse = sensor.Ping();
if (DateTime.Now > nextPrint)
{
float cm = HCSR04.ToCentimeters(pulse);
string cmStr = cm.Equals(Single.MaxValue) ? "?" : cm.ToString("F1");
float inch = HCSR04.ToInches(pulse);
string inStr = inch.Equals(Single.MaxValue) ? "?" : inch.ToString("F1");
Debug.Print("Distance: " + cmStr + " cm = " + inStr + " in");
nextPrint = DateTime.Now.AddSeconds(1);
}
distancePwm.Frequency = ToFrequency(pulse);
distancePwm.DutyCycle = 0.5;
Thread.Sleep(200);
}
}
public static float ToFrequency(TimeSpan pulse)
{
//0-30 cm --> 12-1 Hz
const int barier = 30;//cm
float cm = HCSR04.ToCentimeters(pulse);
if (cm > barier)
{
return(1);
}
const int maxFreq = 12;//Hz
float result = (cm * (1 - maxFreq)) / barier + maxFreq;
return(result);
}
public static void Main()
{
var sensor = new HCSR04(Stm32F4Discovery.FreePins.PC2, Stm32F4Discovery.FreePins.PC1);
//crash detect: red led on or off
var crashLed = new OutputPort(Stm32F4Discovery.LedPins.Red, false);
var scanPeriod = new TimeSpan(0, 0, 0, 0, 100);//100ms
var detector = new CollisionDetector(sensor, scanPeriod) { Barier = 10 }; //10cm
detector.StateChanged += crashLed.Write;
//pwm frequency display (green led linear blink): far->lo freq, near->hi freq
var distancePwm = new PWM(Cpu.PWMChannel.PWM_0, 1, 0, false);
distancePwm.Start();
//print distance every 1s and change pwm freq
DateTime nextPrint = DateTime.Now;
for(;;)
{
TimeSpan pulse = sensor.Ping();
if (DateTime.Now > nextPrint)
{
float cm = HCSR04.ToCentimeters(pulse);
string cmStr = cm.Equals(Single.MaxValue) ? "?" : cm.ToString("F1");
float inch = HCSR04.ToInches(pulse);
string inStr = inch.Equals(Single.MaxValue) ? "?" : inch.ToString("F1");
Debug.Print("Distance: " + cmStr + " cm = " + inStr + " in");
nextPrint = DateTime.Now.AddSeconds(1);
}
distancePwm.Frequency = ToFrequency(pulse);
distancePwm.DutyCycle = 0.5;
Thread.Sleep(200);
}
}
private void TimerTick(object state)
{
TimeSpan pulse = _sensor.Ping();
float distance = HCSR04.ToCentimeters(pulse);
if (distance.Equals(Single.MaxValue))
{
return;
}
bool newState = distance <= Barier;
if (_collision ^ newState)
{
_collision = newState;
StateChangedEventHandler handler = StateChanged;
if (handler != null)
{
StateChanged(_collision);
}
}
}
public CollisionDetector(HCSR04 sensor, TimeSpan scanPeriod)
{
_sensor = sensor;
_timer = new Timer(TimerTick, null, TimeSpan.Zero, scanPeriod);
}
public CollisionDetector(HCSR04 sensor, TimeSpan scanPeriod)
{
_sensor = sensor;
_timer = new Timer(TimerTick, null, TimeSpan.Zero, scanPeriod);
}
