ubitxv6/encoder.cpp

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#include <Arduino.h>
#include <stdint.h>
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#include "encoder.h"
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#include "pin_definitions.h"
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//Normal encoder state
uint8_t prev_enc = 0;
int8_t enc_count = 0;
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//Momentum encoder state
int16_t enc_count_periodic = 0;
int8_t momentum[3] = {0};
static const uint16_t CALLBACK_PERIOD_MS = 200;
static const uint8_t MOMENTUM_MULTIPLIER = 1;
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uint8_t enc_state (void)
{
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return (digitalRead(PIN_ENC_A)?1:0 + digitalRead(PIN_ENC_B)?2:0);
}
/*
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* SmittyHalibut's encoder handling, using interrupts. Should be quicker, smoother handling.
* The Interrupt Service Routine for Pin Change Interrupts on A0-A5.
*/
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ISR (PCINT1_vect)
{
uint8_t cur_enc = enc_state();
if (prev_enc == cur_enc) {
//Serial.println("unnecessary ISR");
return;
}
//Serial.print(prev_enc);
//Serial.println(cur_enc);
//these transitions point to the enccoder being rotated anti-clockwise
if ((prev_enc == 0 && cur_enc == 2) ||
(prev_enc == 2 && cur_enc == 3) ||
(prev_enc == 3 && cur_enc == 1) ||
(prev_enc == 1 && cur_enc == 0))
{
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enc_count -= 1;
enc_count_periodic -= 1;
}
//these transitions point to the enccoder being rotated clockwise
else if ((prev_enc == 0 && cur_enc == 1) ||
(prev_enc == 1 && cur_enc == 3) ||
(prev_enc == 3 && cur_enc == 2) ||
(prev_enc == 2 && cur_enc == 0))
{
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enc_count += 1;
enc_count_periodic += 1;
}
else {
// A change to two states, we can't tell whether it was forward or backward, so we skip it.
//Serial.println("skip");
}
prev_enc = cur_enc; // Record state for next pulse interpretation
}
/*
* Setup the encoder interrupts and global variables.
*/
void pci_setup(byte pin) {
*digitalPinToPCMSK(pin) |= bit (digitalPinToPCMSKbit(pin)); // enable pin
PCIFR |= bit (digitalPinToPCICRbit(pin)); // clear any outstanding interrupt
PCICR |= bit (digitalPinToPCICRbit(pin)); // enable interrupt for the group
}
void enc_setup(void)
{
enc_count = 0;
// This is already done in setup() ?
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//pinMode(PIN_ENC_A, INPUT);
//pinMode(PIN_ENC_B, INPUT);
prev_enc = enc_state();
// Setup Pin Change Interrupts for the encoder inputs
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pci_setup(PIN_ENC_A);
pci_setup(PIN_ENC_B);
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//Set up timer interrupt for momentum
TCCR1A = 0;//"normal" mode
TCCR1B = 3;//clock divider of 64
TCNT1 = 0;//start counting at 0
OCR1A = F_CPU * (unsigned long)CALLBACK_PERIOD_MS / 1000 / 64;//set target number
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TIMSK1 |= (1 << OCIE1A);//enable interrupt
}
ISR(TIMER1_COMPA_vect)
{
momentum[2] = momentum[1];
momentum[1] = momentum[0];
momentum[0] = enc_count_periodic;
enc_count_periodic = 0;
}
int8_t min_momentum_mag()
{
int8_t min_mag = 127;
for(uint8_t i = 0; i < sizeof(momentum)/sizeof(momentum[0]); ++i){
int8_t mag = abs(momentum[i]);
if(mag < min_mag){
min_mag = mag;
}
}
return min_mag;
}
int enc_read(void) {
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if(0 != enc_count){
int16_t ret = enc_count;
int8_t s = (enc_count < 0) ? -1 : 1;
int8_t momentum_mag = min_momentum_mag();
if(momentum_mag >= 20){
ret += s*40;
}
else if(momentum_mag >= 5){
ret += s*(20 + momentum_mag)/(20 - momentum_mag);
}
enc_count = 0;
return ret;
}
return 0;
}