Hey, my readings are nonsense…
Perhaps someone can look over it give some good advise?
I’m using the HCSR04 sensor driven with 5V. pins 15 & 16 on the daisy are 5V tolerant. so I use them with the sensor. Sending a 3.3V volt trigger gate.
any help would help 
cheers!
main.cpp
#define U_SONIC_PIN_TRIGGER D15
#define U_SONIC_PIN_ECHO D16
void InitEcholot()
{
echolot.Init(U_SONIC_PIN_TRIGGER, U_SONIC_PIN_ECHO);
}
float GetEcholotDistance(){
return echolot.measureDistanceCm();
}
HCSR04.h
#pragma once
#include "daisy_seed.h"
using namespace daisy;
class UltraSonicDistanceSensor {
public:
/**
* @param triggerPin Digital pin that is used for controlling sensor (output).
* @param echoPin Digital pin that is used to get information from sensor (input).
* @param maxDistanceCm Maximum distance sensor can measure, defaults to 4m for HC-SR04.
* You might want to set this value if you are using different sensor than HC-SR04
* or if you don't care about distances larger than whatever you will set it to
* (therefore reducing time it takes for a single measurement).
* @param maxTimeoutMicroSec Single measurement will never take longer than whatever value you provide here.
* You might want to do this in order to ensure your program is never blocked for longer than some specific time,
* since measurements are blocking.
* By default, there is no limit on time (only on distance). By defining timeout, you are again limiting the distance.
*/
UltraSonicDistanceSensor(){};
~UltraSonicDistanceSensor(){};
/**
* Measures distance by sending ultrasonic waves and measuring time it takes them
* to return.
* @returns Distance in centimeters, or negative value if distance is greater than 400cm.
*/
void Init(Pin triggerPin, Pin echoPin,
unsigned short maxDistanceCm = 400,
unsigned long maxTimeoutMicroSec );
float measureDistanceCm();
/**
* Measures distance by sending ultrasonic waves and measuring time it takes them
* to return. Measurement can not exceed duration calculated with maxDistanceCm or maxTimeoutMicroSec.
* @param temperature Temperature in degrees celsius
* @returns Distance in centimeters, or negative value if distance is greater than 400cm.
*/
float measureDistanceCm(float temperature);
unsigned short maxDistanceCm;
unsigned long maxTimeoutMicroSec;
private:
unsigned long pulseInSimpl(GPIO pin, bool state, unsigned long maxloops);
GPIO triggerPin_, echoPin_;
};
void UltraSonicDistanceSensor::Init(
Pin triggerPin, Pin echoPin, unsigned short maxDistanceCm, unsigned long maxTimeoutMicroSec) {
this->maxDistanceCm = maxDistanceCm;
this->maxTimeoutMicroSec = maxTimeoutMicroSec;
echoPin_.Init(echoPin, GPIO::Mode::INPUT, GPIO::Pull::NOPULL);
triggerPin_.Init(triggerPin, GPIO::Mode::OUTPUT);
}
float UltraSonicDistanceSensor::measureDistanceCm() {
//Using the approximate formula 19.307°C results in roughly 343m/s which is the commonly used value for air.
return measureDistanceCm(19.307);
}
float UltraSonicDistanceSensor::measureDistanceCm(float temperature) {
unsigned long maxDistanceDurationMicroSec;
// Make sure that trigger pin is LOW.
triggerPin_.Write(0);
System::DelayUs(2);
// Hold trigger for 10 microseconds, which is signal for sensor to measure distance.
triggerPin_.Write(1);
System::DelayUs(10);
triggerPin_.Write(0);
float speedOfSoundInCmPerMicroSec = 0.03313 + 0.0000606 * temperature; // Cair ≈ (331.3 + 0.606 ⋅ ϑ) m/s
// Compute max delay based on max distance with 25% margin in microseconds
maxDistanceDurationMicroSec = 2.5 * maxDistanceCm / speedOfSoundInCmPerMicroSec;
if (maxTimeoutMicroSec > 0) {
maxDistanceDurationMicroSec = std::min(maxDistanceDurationMicroSec, maxTimeoutMicroSec);
}
// Measure the length of echo signal, which is equal to the time needed for sound to go there and back.
unsigned long durationMicroSec = pulseInSimpl(echoPin_, 1, maxDistanceDurationMicroSec); // can't measure beyond max distance
float distanceCm = durationMicroSec / 2.0 * speedOfSoundInCmPerMicroSec;
if (distanceCm == 0 || distanceCm > maxDistanceCm) {
return -1.0 ;
} else {
return distanceCm;
}
}
unsigned long UltraSonicDistanceSensor::pulseInSimpl(GPIO pin, bool state, unsigned long maxloops)
{
unsigned long width = 0;
// wait for any previous pulse to end
while (pin.Read() == state)
if (--maxloops == 0)
return 0;
// wait for the pulse to start
while (pin.Read() != state)
if (--maxloops == 0)
return 0;
// wait for the pulse to stop
while (pin.Read() == state) {
if (++width == maxloops)
return 0;
}
return width;
}