screenlight/firmware/main.c

/* This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <stdint.h> // Standard Integer Types
#include <stdio.h> // Standard IO facilities
#include <stdlib.h> // General utilities
#include <stdbool.h> // Boolean
#include <string.h> // Strings

#include <avr/io.h> // AVR device-specific IO definitions
#include <util/delay.h> // Convenience functions for busy-wait delay loops
#include <avr/interrupt.h> // Interrupts
#include <avr/wdt.h> // Watchdog timer handling
#include <avr/pgmspace.h> // Program Space Utilities
#include <avr/sleep.h> // Power Management and Sleep Modes

#include "main.h" // main definitions
#include "uart.h" // basic UART functions
#include "ws2812b.h" // to control WS2812B LEDs

/* global variables */
const uint8_t leds_per_channel[WS2812B_NB_CHANNELS] = {11,5,9,11,5,9}; // the led strips (top 1, top 2, left, bottom 1, bottom 2, right)
uint8_t nb_leds = 0; // the total number of LEDs (will be calculated on the number of LEDs per channel)
volatile uint8_t uart_in[16]; // input from USART, enough space for one fnordlight command or sync sequence

/* flags, set in the interrupts and handled in the main program */
volatile bool uart_flag = false; // data on UART has been received
volatile char uart_char = 0; // UART data
volatile bool command_flag = false; // a command has been received

/* switch off LED */
void led_off(void)
{
	LED_PORT &= ~(1<<LED_IO); // remove power to LED
}

/* switch on LED */
void led_on(void)
{
	LED_PORT |= (1<<LED_IO); // provide power to LED
}

/* toggle LED */
void led_toggle(void)
{
	LED_PIN |= (1<<LED_IO);
}

/* disable watchdog when booting */
void wdt_init(void) __attribute__((naked)) __attribute__((section(".init3")));
void wdt_init(void)
{
	MCUSR = 0;
	wdt_disable();

	return;
}

/* receive UART input */
ISR(USART_RX_vect) { /* UART receive interrupt */
	uart_char = getchar(); // save current character
	uart_flag = true; // warm main programm
}

/* process command */
void command_action(void)
{
	/* parse command */
	switch (uart_in[1]) {
		case 0x01: // set LED colors
			if (uart_in[0]<nb_leds) { // set LED color
				for (uint8_t channel = 0; channel<sizeof(leds_per_channel); channel++) { // find right channel
						if (uart_in[0]<leds_per_channel[channel]) { // find right LED
							ws2812b_set_led_color(channel,uart_in[0],uart_in[4],uart_in[5],uart_in[6]);
							break;
						} else {
							uart_in[0] -= leds_per_channel[channel]; // go to next channel
						}
				}
			} else { // use additional LED setting as signal to show the LEDs
				ws2812b_show();
			}
			break;
		case 0x08: // stop color changing
			ws2812b_show(); // use this as flush command
			break;
		case 0x80: // start bootloader
		case 0x87: // start application
			ws2812b_off();
			ws2812b_show();
			break;
		default:
			break; // all other commands are not relevant
	}
}

/* initialize GPIO */
void io_init(void)
{
	/* use UART as terminal */
	uart_init();
	stdout = &uart_output;
	stdin  = &uart_input;

	/* gpio */
	/* LED */
	LED_DDR |= (1<<LED_IO); // LED is driven by pin (set as output)
	led_off();
	
	sei(); /* enable interrupts */
	
	/* WS2812B LEDs */
	ws2812b_init();
	ws2812b_off();
	ws2812b_show();
}

int main(void)
{
	uint8_t uart_in_i = 0; // UART input index
	uint8_t escape_count = 0; // number of escape bytes received
	
	io_init(); // initialize IOs
	
	/* count the total number of LEDs */
	for (uint8_t i=0; i<sizeof(leds_per_channel); i++) {
		nb_leds += leds_per_channel[i];
	}
	
	led_on();
	printf(PSTR("welcome on the VLC+fnordlicht+WS2812B AtmoLight\n"));
	led_off();
	
	while (true) { // endless loop for micro-controller
		while (uart_flag) {
			/* go to next character but next got pass the last
			 * only sync sequences can be longer than 15, but should only be 16
			 * but sometimes (bug) they are longer
			 * then ignore the escape byte until the sequence ends
			 */
			uart_in[uart_in_i] = uart_char;
			if (uart_in_i<sizeof(uart_in)-1) {
				uart_in_i++;
			}
			
			if (uart_char==0x1b) { // escape byte received
				if (escape_count<15) { // there should be maximum 15 escape bytes. ignore all additional
					escape_count++; // count number of escape bytes
				}
			} else {
				if (escape_count>=15) { // end of sync sequence
					uart_in_i = 0; // reset input but don't handle sync sequence
				}
				escape_count = 0; // restart count
			}
			if (uart_in_i>=15 && escape_count<15) { // end of command
				command_flag = true; // notify a command is ready
				uart_in_i = 0; // reset input
			}
			uart_flag = false;
		}
		while (command_flag) { // UART input command is ready
			led_on();
			command_action(); // process command
			command_flag = false; // clear flag
			led_off();
		}
	}
	return 0;
}