/***********************************************************
* hello.piezo.c
*
* based on hello.mag.45.c by Neil Gershenfeld
*      and http://www.protostack.com/blog/2011/02/analogue-to-digital-conversion-on-an-atmega168/
*      and button44 by Rob Hart
* set lfuse to 0x5E for 20 MHz xtal
*
* Adds ADC conversion to the hello piezo
*
* Brian Plancher
* 11/02/16
*
***********************************************************/

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <util/delay.h>

// helper defs
#define output(directions,pin) (directions |= pin) // set port direction for output
#define input(directions,pin) (directions &= (~pin)) // set port direction for input
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set

// input and output devices
// Piezo   PA5
// Button1 PA6
// Button1 PA7
// LED1    PA2
// LED2    PA3
// LED3    PA4
#define input_port PORTA		// The button is on port A
#define input_direction DDRA	//  DDRA defines input/output for port A
#define piezo_pin (1 << PA6)   //  The button is on pin 5 of port A
#define button1_pin (1 << PA6)	//  The button is on pin 6 of port A
#define button2_pin (1 << PA7)   //  The button is on pin 7 of port A
#define input_pins PINA			//  PINA is the register that is read to detect input high or low.
#define LED_port PORTA		//  port A will be used for the LED
#define LED_direction DDRA
#define LED1_pin (1 << PA2)
#define LED2_pin (1 << PA3)
#define LED3_pin (1 << PA4)

int main(void) {
   
   // set clock divider to /1
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   // initialize pins
   output(LED_direction, LED1_pin|LED2_pin|LED3_pin); // sed LEDs for output
   set(input_port, button1_pin|button2_pin); // turn on pull-up for the buttons
   input(input_direction, button1_pin|button2_pin|piezo_pin); // make buttons and piezos input
   
   // init A/D for the piezo
   ADMUX = (0 << REFS2) | (0 << REFS1) | (0 << REFS0) // Vcc ref
      | (0 << ADLAR) // right adjust
      | (0 << MUX3) | (1 << MUX2) | (0 << MUX1) | (1 << MUX0); // ADC5 is PA 5
   ADCSRA = (1 << ADEN) // enable
      | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); // prescaler /128
   
   // main loop
   while (1) {
      // use LED 2 and 3 for the piezo level
      piezo_flag = ADCSRA & (1 << ADSC); // tests if in an active ADC conversion
      // ADC done or not started
      if (~piezo_flag){
         ADCSRA |= (1 << ADSC); // run it again
         int piezo_val = ADC; // 16 bit val
         // 16 bit means 65536 so if >3000 then both lights
         // if >1500 then second lights
         // if >500 then first light else none
         if (piezo_val > 3000){
            set(LED_port,LED1_pin);
            set(LED_port,LED2_pin);
         }
         else if(piezo_val > 1500){
            set(LED_port,LED2_pin);
         }
         else if(piezo_val > 500){
            set(LED_port,LED1_pin);
         }
         else{
            clear(LED_port,LED2_pin);
            clear(LED_port,LED3_pin);
         }
      }
      
      // combine the buttons on one LED
      int btn1_flag = pin_test(input_pins,button1_pin);
      int btn2_flag = pin_test(input_pins,button2_pin);
      if (btn1_flag & btn2_flag){
         clear(LED_port,LED1_pin);
      }
      else{
         set(LED_port,LED1_pin);
      }
   }
   return 0;   
}