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encoder.cpp
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encoder.cpp
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// This software is part of OpenMono, see http://developer.openmono.com
// Released under the MIT license, see LICENSE.txt
#include "encoder.hpp"
#include "constants.hpp"
Encoder::Encoder (PinName pinA, PinName pinB)
:
lastA(0),
lastB(0),
channelA(pinA),
channelB(pinB)
{
#ifndef EMUNO
// Pull up A.
CyPins_SetPinDriveMode(pinA, CY_PINS_DM_RES_UP);
CyPins_SetPin(pinA);
// Pull up B.
CyPins_SetPinDriveMode(pinB, CY_PINS_DM_RES_UP);
CyPins_SetPin(pinB);
#endif
reset();
#ifndef EMUNO
// Samples every 100µs.
ticker.attach_us(this, &Encoder::sample, 100);
#endif
}
void Encoder::reset ()
{
pulses = 0;
}
int Encoder::getPulses ()
{
return pulses;
}
void Encoder::sample ()
{
uint8_t a = channelA.read();
uint8_t b = channelB.read();;
if (a != lastA || b != lastB)
{
translate(a, b);
lastA = a;
lastB = b;
}
}
void Encoder::translate (uint8_t a, uint8_t b)
{
// 00 -> 01 -> 11 -> 10 -> ... = clockwise rotation.
if (
(lastA == 0 && lastB == 0 && a == 0 && b >= 1) ||
(lastA == 0 && lastB >= 1 && a >= 1 && b >= 1) ||
(lastA >= 1 && lastB >= 1 && a >= 1 && b == 0) ||
(lastA >= 1 && lastB == 0 && a == 0 && b == 0)
)
{
++pulses;
}
// 01 -> 00 -> 10 -> 11 -> ... = counter clockwise rotation.
else if (
(lastA == 0 && lastB >= 1 && a == 0 && b == 0) ||
(lastA == 0 && lastB == 0 && a >= 1 && b == 0) ||
(lastA >= 1 && lastB == 0 && a >= 1 && b >= 1) ||
(lastA >= 1 && lastB >= 1 && a == 0 && b >= 1)
)
{
--pulses;
}
}