PIE/ditial_write_speed.ino at main · bminch/PIE · GitHub

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/*
** Copyright (c) 2021, Bradley A. Minch
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are met:
**
**     1. Redistributions of source code must retain the above copyright
**        notice, this list of conditions and the following disclaimer.
**     2. Redistributions in binary form must reproduce the above copyright
**        notice, this list of conditions and the following disclaimer in the
**        documentation and/or other materials provided with the distribution.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
** AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
** IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
** LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
** INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
** CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
** ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
** POSSIBILITY OF SUCH DAMAGE.
*/

#define D0_PORT   PORTD
#define D1_PORT   PORTD
#define D2_PORT   PORTD
#define D3_PORT   PORTD
#define D4_PORT   PORTD
#define D5_PORT   PORTD
#define D6_PORT   PORTD
#define D7_PORT   PORTD
#define D8_PORT   PORTB
#define D9_PORT   PORTB
#define D10_PORT  PORTB
#define D11_PORT  PORTB
#define D12_PORT  PORTB
#define D13_PORT  PORTB

#define D0_BIT    0b00000001
#define D1_BIT    0b00000010
#define D2_BIT    0b00000100
#define D3_BIT    0b00001000
#define D4_BIT    0b00010000
#define D5_BIT    0b00100000
#define D6_BIT    0b01000000
#define D7_BIT    0b10000000
#define D8_BIT    0b00000001
#define D9_BIT    0b00000010
#define D10_BIT   0b00000100
#define D11_BIT   0b00001000
#define D12_BIT   0b00010000
#define D13_BIT   0b00100000

#define digitalPinSet(p, b)     p |= b
#define digitalPinClear(p, b)   p &= (~b)
#define digitalPinToggle(p, b)  p ^= b

const uint16_t LOOP_INTERVAL = 5;

uint32_t loop_time;

/*
** Returns a boolean value that indicates whether the current time, t, is later than some prior
** time, t0, plus a given interval, dt.  The condition accounts for timer overflow / wraparound.
*/
bool it_is_time(uint32_t t, uint32_t t0, uint16_t dt) {
  return ((t >= t0) && (t - t0 >= dt)) ||         // The first disjunct handles the normal case
            ((t < t0) && (t + (~t0) + 1 >= dt));  //   while the second handles the overflow case
}

void setup() {
  pinMode(13, OUTPUT);
  digitalWrite(13, LOW);

  loop_time = millis();
}

void loop() {
  uint32_t t;

  t = millis();
  if (it_is_time(t, loop_time, LOOP_INTERVAL)) {
    digitalWrite(13, HIGH);
    digitalWrite(13, LOW);
    digitalWrite(13, HIGH);
    digitalWrite(13, LOW);

    digitalPinSet(D13_PORT, D13_BIT);
    digitalPinClear(D13_PORT, D13_BIT);
    digitalPinSet(D13_PORT, D13_BIT);
    digitalPinClear(D13_PORT, D13_BIT);

    digitalPinToggle(D13_PORT, D13_BIT);
    digitalPinToggle(D13_PORT, D13_BIT);
    digitalPinToggle(D13_PORT, D13_BIT);
    digitalPinToggle(D13_PORT, D13_BIT);

    loop_time = t;
  }
}