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main.c
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main.c
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#define F_CPU 8000000 // Clock Speed
#define BAUD 1200
#define MYUBRR F_CPU/16/BAUD-1
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <stdlib.h>
#include "main.h"
#include <string.h>
uint8_t brygger_status = 0;
uint8_t nybryggt_status = 0;
uint8_t last_min = 255;
volatile uint16_t second_counter = 0;
uint8_t average = 0;
double average_factor = 0.2; // "constant smoothing factor
// between 0 and 1. A higher α discounts older observations faster"
char string[20];
char time[5];
int main(void)
{
init_timer();
init_uart(MYUBRR);
init_adc();
srand(read_adc());
// Setup the I/O for the status LED
DDRB |= (1<<7); // Set PortB Pin7 as an output
PORTB &= ~(1<<7); // Set PortB Pin7 LOW to turn ON LED
//PORTB |= (1<<7); // Set PortB Pin7 HIGH to turn OFF LED
uart_send(0x3C); // Enable Screen Saver, dims after 10 min idle
uart_send(0x0E); // Remove cursor
uart_send(0x15); // Clear display
while(1) {
// Read kaffebryggare current
_delay_ms(1000);
uint8_t data = read_adc();
uint8_t result = average_value(data);
// Check current to kaffebryggare
if(result > ADC_threshold) { // Current is high
if(brygger_status == 0) { // If starting to brew
uart_send(0x15); // Clear display
// Write do display
int random = rand()%200;
if(random == 0) {
uart_str(egg);
}
else if(random == 1) {
uart_str(golv);
}
else {
uart_str(brygger_kaffe);
}
brygger_status = 1;
nybryggt_status = 1;
}
}
else { // Current is low
if(nybryggt_status == 1) { // If brew completed
activate_counter1();
// Send CAN message
nybryggt_status = 0;
brygger_status = 0;
}
else if(second_counter > 60*90) { // If coffee is old
deactivate_counter1();
uart_send(0x15); // Clear display
uart_str(brygg_nytt);
}
else if(brygger_status == 0) { // If brew is finished
reset_string(string);
reset_string(time);
if(second_counter/60 != last_min) { // Only update display if new minute
uart_send(0x15); // Clear display
itoa(second_counter/60, time, 10); // Convert time to string
// Build output string
strcat(string, time);
if(second_counter/60 == 1) {
strcat(string, kaffe_gammalt_singular);
}
else {
strcat(string, kaffe_gammalt);
}
uart_str(string);
}
last_min = second_counter/60;
}
}
}
}
// Implements an Exponential moving average filter
uint8_t average_value(uint8_t last_value) {
average = average_factor * last_value + (1-average_factor) * average;
return average;
}
void activate_counter1() {
second_counter = 0;
TCNT1 = 0; // Set initial count value to zero
TIMSK1 |= 1<<OCIE1A; // Enable timer compare interrupt
}
void deactivate_counter1() {
TIMSK1 &= ~(1<<OCIE1A); // Disable timer compare interrupt
}
// Sends a single char. Blocks processor.
void uart_send(unsigned char data) {
// Wait for empty transmit buffer
while ( !( UCSR0A & (1<<UDRE0)) );
// Send message buffer content
UDR0 = data;
}
void uart_str(char *msg) {
for(uint8_t x = 0 ; msg[x] != '\0' ; x++) {
uart_send(msg[x]);
}
}
void init_timer(void) {
//Setup the clock
cli(); // Disable global interrupts
TCCR1B |= 1<<CS11 | 1<<CS10; // Divide by 64 -> Clock freq = 39062 Hz
OCR1A = 39062; // Count 15624 cycles for 1 second interrupt
TCCR1B |= 1<<WGM12; // Put Timer/Counter1 in CTC mode
TCNT1 = 0; // Reset count register
TIFR1 &= !(1<<OCF1A); // Reset Timer/Counter1, output compare A match flag
sei(); // Enable global interrupts
}
ISR(TIMER1_COMPA_vect) {
second_counter++;
TIFR1 &= !(1<<OCF1A); // Reset Timer/Counter1, output compare A match flag
}
void init_uart(unsigned int ubrr) {
cli(); //Disable global interrupts
// Set baud rate
UBRR0H = (unsigned char)(ubrr>>8);
UBRR0L = (unsigned char)ubrr;
UCSR0C &= ~((1 << UPM00) | (1 << UPM01)); // No parity
UCSR0C &= ~(1 << USBS0); // 1 stop bit
UCSR0B |= (1 << TXEN0); // Enable transmitter
sei(); //Enable global interrupts
}
void init_adc() {
cli();
ADMUX |= (1 << MUX1); // Use ADC2
ADMUX |= (1 << ADLAR); // Left adjust result (highest 8-bits in ADCH reg)
ADCSRA |= (1 << ADEN); // Activate ADC
ADCSRA |= (1 << ADPS2); // Set ADC prescale to .
ADCSRA |= (1 << ADPS1);
ADCSRA |= (1 << ADPS0);
sei();
}
uint8_t read_adc() {
ADCSRA |= (1 << ADSC); // Start ADC conversion
while(ADCSRA & (1 << ADSC)); // Wait for measurement to complete
return ADCH;
}
void reset_string(char *str) {
for(uint8_t x = 0 ; str[x] != '\0' ; x++) {
str[x] = 0;
}
}