238 lines
7.7 KiB
C
238 lines
7.7 KiB
C
/* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <stdint.h> // Standard Integer Types
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#include <stdio.h> // Standard IO facilities
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#include <stdlib.h> // General utilities
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#include <stdbool.h> // Boolean
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#include <string.h> // Strings
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#include <avr/io.h> // AVR device-specific IO definitions
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#include <util/delay.h> // Convenience functions for busy-wait delay loops
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#include <avr/interrupt.h> // Interrupts
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#include <avr/wdt.h> // Watchdog timer handling
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#include <avr/pgmspace.h> // Program Space Utilities
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#include <avr/sleep.h> // Power Management and Sleep Modes
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#include "uart.h" // basic UART functions
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#include "main.h" // main definitions
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/* contants */
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// max measurement jitter for high and low value 8/3
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#define JITTER_HIGH 11
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#define JITTER_LOW 5
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// how many value have to be stable before showing output
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#define MEASUREMENT_STABLE 3
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/* variables */
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volatile uint8_t state_portD; // the state of port D
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volatile bool scale_on = false; // is the scale on (based on the SCALE_ON PIN)
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volatile bool scale_old = false; // the previous state (to detect changes)
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volatile bool pwm_high = false; // is the PWM for the weight measurement high
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volatile bool measurement_flag = false; // is a PWM measurement value ready
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volatile uint16_t measurement_value = 0; // the PWM measurement value from the timer
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/* switch off LED */
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void led_off(void)
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{
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PORTB &= ~(1<<LED); // remove power to LED
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}
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/* switch on LED */
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void led_on(void)
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{
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PORTB |= (1<<LED); // provide power to LED
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}
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/* toggle LED */
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void led_toggle(void)
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{
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PINB |= (1<<LED);
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}
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/* scale on interrupt
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* PCI2 Interrupt Vector for PCINT[23:16]/PORTD
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*/
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ISR(PCINT2_vect)
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{
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if ((state_portD&(1<<SCALE_ON))!=(PIND&(1<<SCALE_ON))) { // scale on state changed
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if (PIND&(1<<SCALE_ON)) {
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scale_on = true;
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led_on();
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} else {
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scale_on = false;
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led_off();
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}
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}
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state_portD = PIND; // save new state
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}
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/* PWM weight signal
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* analog comparator interrupt
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*/
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ISR(ANALOG_COMP_vect)
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{
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if (scale_on && !measurement_flag) { // only save value if scale is on and previous value is read
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measurement_value = TCNT1; // save value
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TCNT1 = 0; // reset timer
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if (ACSR&(1<<ACO)) { // PWM raising edge
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pwm_high = false;
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led_on();
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} else { // PWM falling edge
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pwm_high = true;
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led_off();
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}
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measurement_flag = true; // signal new value is ready
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}
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}
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/* disable watchdog when booting */
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void wdt_init(void) __attribute__((naked)) __attribute__((section(".init3")));
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void wdt_init(void)
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{
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MCUSR = 0;
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wdt_disable();
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return;
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}
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/* initialize GPIO */
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void io_init(void)
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{
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/* use UART as terminal */
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uart_init();
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stdout = &uart_output;
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stdin = &uart_input;
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/* gpio */
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/* LED */
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DDRB |= (1<<LED); // LED is driven by pin (set as output)
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led_off();
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/* scale on signal */
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DDRD &= ~(1<<SCALE_ON); // SIGNAL_ON is input (should be per default)
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PCIFR &= ~(1<<PCIF2); // clear interrupt flag for SCALE_ON on PCINT[23:16]/PORTD
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PCICR |= (1<<PCIE2); // enable interrupt for PCINT[23:16]/PORTD
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PCMSK2 |= (1<<PCINT21); // enable interrupt for SCALE_ON
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state_portD = PIND; // save state to detect change
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/* PWM scale weight signal on analog comparator */
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DDRD &= ~((1<<SCALE_PWM)|(1<<REF_PWM)); // analog comparator is input (should be per default)
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ADCSRA &= ~(1<<ADEN); // switch off ADC
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ADCSRB &= ~(1<<ACME); // disable analog comparator multiplexer, use AIN1 as negative input (should be per default)
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ACSR &= ~(1<<ACD); // enable analog comparator (should be per default)
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ACSR &= ~(1<<ACBG); // use AIN0 as positiv input (should be per default)
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ACSR |= (1<<ACI); // clear analog comparator interrup flag
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ACSR &= ~((1<<ACIS1)|(1<<ACIS0)); // comparator interrupt on output toggle
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DIDR1 |= ((1<<AIN1D)|(1<<AIN0D)); // disable digital input buffer on AIN0 and AIN1
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ACSR |= (1<<ACIE); // enable analog comparator interrupt
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/* use timer 1 (with capture unit) to measure PWM */
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TCCR1A &= ~((1<<WGM11)|(1<<WGM10)); // mode 0: normal (should be per default)
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TCCR1B &= ~((1<<WGM13)|(1<<WGM12)); // mode 0: normal (should be per default)
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TCCR1B |= (1<<CS12)|(0<<CS11)|(0<<CS10); // set prescale to 256 for 1.048576s before overflow (PWM should be 3Hz)
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sei(); /* enable interrupts */
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}
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int main(void)
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{
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uint16_t measurement_high = 0, measurement_low = 0; // the average measurement value
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uint16_t zero_high = 0, zero_low = 0; // the intial zero value
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uint8_t count_high = 0, count_low = 0; // the number of stable counts
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io_init(); // initialize IOs
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printf(PSTR("welcome to the body scale weight reader\n")); // print welcome message
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while (true) { // endless loop for micro-controller
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/* display if scale switches on */
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if (scale_old!=scale_on && scale_on) {
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#ifdef DEBUG
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printf(PSTR("scale start\n"));
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#endif
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measurement_high = measurement_low = zero_high = zero_low = count_high = count_low = 0; // re-initialize values
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scale_old = scale_on; // save new state
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}
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/* display value if available */
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if (measurement_flag) {
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if (pwm_high) {
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#ifdef DEBUG
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printf("high: %u\n", measurement_value);
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#endif
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if (measurement_value<=measurement_high+JITTER_HIGH && measurement_value>=measurement_high-JITTER_HIGH) { // stable value
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measurement_high = (measurement_high+measurement_value)/2;
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count_high += 1;
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} else {
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measurement_high = measurement_value;
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count_high = 0;
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}
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} else {
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#ifdef DEBUG
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printf("low: %u\n", measurement_value);
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#endif
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if (measurement_value<=measurement_low+JITTER_LOW && measurement_value>=measurement_low-JITTER_LOW) { // stable value
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measurement_low = (measurement_low+measurement_value)/2;
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count_low += 1;
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} else {
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measurement_low = measurement_value;
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count_low = 0;
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}
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}
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#ifdef DEBUG
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printf("values high/low (stable): %u (%u)/%u (%u)\n", measurement_high, count_high, measurement_low, count_low);
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#endif
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measurement_flag = false;
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}
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/* display weight if values are stable */
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if (count_high>=MEASUREMENT_STABLE && count_low>=MEASUREMENT_STABLE) {
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if (zero_high == 0 && zero_low == 0) { // initialize zero values
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zero_high = measurement_high;
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zero_low = measurement_low;
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#ifdef DEBUG
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printf("zero values high low: %u %u\n", zero_high, zero_low);
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#endif
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count_high = count_low = 0;
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} else { // print measurement weight
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#ifdef DEBUG
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printf("%u %u 0\n", zero_high, zero_low);
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printf("%u %u t1\n", measurement_high, measurement_low);
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#endif
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// the low measurement are linear and more stable
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// normally it should not have a origin, but the linear estimation shows one and it works better
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const double orig_low = -1.92285;
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const double coef_low = 0.0258119;
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double weight_low = (int16_t)(measurement_low-zero_low)*coef_low+orig_low;
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if (weight_low<orig_low*-1.5 && weight_low>orig_low*1.5) {
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weight_low = 0;
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}
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printf("%.2f kg\n", weight_low);
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}
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count_high = count_low = 0;
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}
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/* display if scale switches off */
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if (scale_old!=scale_on && !scale_on) {
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#ifdef DEBUG
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printf(PSTR("scale stop\n")); // actually measurement is finished and the on switch is released
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#endif
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scale_old = scale_on; // save new state
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}
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/* go to sleep and wait for next interrupt */
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set_sleep_mode(SLEEP_MODE_IDLE);
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sleep_mode();
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}
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return 0;
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}
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