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/*
* The MIT License (MIT)
*
* Copyright (c) 2019 Matthias P. Braendli
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <stdlib.h>
#include <stdint.h>
#include <avr/pgmspace.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
// Definitions allocation pin
#define PIN(x) (1 << x)
/* ALL relay signals PINx_Kx have external pulldown.
* All pins whose name ends in 'n' are active low */
// PORT B
constexpr uint8_t PINB_STATUSn = PIN(0);
// Pins 2,3,4,5 = SPI
constexpr uint8_t PINB_SPI_LTC_CSn = PIN(2); // with external pullup
constexpr uint8_t PINB_SPI_MOSI = PIN(3);
constexpr uint8_t PINB_SPI_MISO = PIN(4);
constexpr uint8_t PINB_SPI_SCK = PIN(5);
constexpr uint8_t PINB_OUTPUTS =
PINB_STATUSn | PINB_SPI_SCK | PINB_SPI_MOSI | PINB_SPI_LTC_CSn;
// PORT C
constexpr uint8_t PINC_ADC0 = PIN(0);
constexpr uint8_t PINC_ADC1 = PIN(1);
constexpr uint8_t PINC_K3_RESET = PIN(2);
constexpr uint8_t PINC_K3_SET = PIN(3);
constexpr uint8_t PINC_K2_RESET = PIN(4);
constexpr uint8_t PINC_K2_SET = PIN(5);
constexpr uint8_t PINC_OUTPUTS =
PINC_K3_RESET | PINC_K3_SET |
PINC_K2_RESET | PINC_K2_SET;
// PORT D
// Pins 0,1 = UART RX,TX
constexpr uint8_t PIND_UART_RX = PIN(0);
constexpr uint8_t PIND_UART_TX = PIN(1);
constexpr uint8_t PIND_ONEWIRE = PIN(4); // with exteral pullup
constexpr uint8_t PIND_K1_RESET = PIN(5);
constexpr uint8_t PIND_K1_SET = PIN(6);
constexpr uint8_t PIND_OUTPUTS =
PIND_UART_TX |
PIND_K1_RESET | PIND_K1_SET;
/* Assuming F_CPU at 16MHz / 8:
*
* overflow for 100ms: F_CPU [ticks/s] / prescaler [unit-less] * interval [s] = [ticks/s*s] = [ticks]
* interval [s] = 0.1 = 1 / 10
*
* Actual interval after rounding:
* interval [s] = overflow [ticks] / (F_CPU [ticks/s] / prescaler [unit-less])
* = 99.84 ms
*/
volatile uint8_t timer_counter; /* Timer */
ISR(TIMER0_COMPA_vect)
{
timer_counter++;
}
int main()
{
/* Setup GPIO */
// Active-low outputs must be high
PORTB = PINB_STATUSn | PINB_SPI_LTC_CSn;
PORTC = 0;
PORTD = 0;
// Enable output
DDRB = PINB_OUTPUTS;
DDRC = PINC_OUTPUTS;
DDRD = PIND_OUTPUTS;
/* Setup 100Hz timer */
TCCR0B |= (1 << WGM02); // Set timer mode to CTC (datasheet 15.7.2)
TIMSK0 |= (1 << TOIE0); // enable overflow interrupt
OCR0A = (uint8_t)(F_CPU / 1024 / 10); // Overflow at 99.84 ms
TCCR0B |= (1 << CS02) | (1 << CS00); // Start timer at Fcpu/1024
/* Enable interrupts */
sei();
/* Put the CPU to sleep */
set_sleep_mode(SLEEP_MODE_IDLE);
sleep_enable();
while (true) {
sleep_cpu();
}
return 0;
}
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