// File: hello2.c
//
// Nearly simple "hello, world" program, similar to the 
// hello.c program, but uses sleep() and watchdog timer 
// to wake from sleep rather than a programmed 500 mSec
// delay.  The PIC16F84 processor on the iRX board draws
// very little current when in sleep mode.
//
// Robert Poor <r@media.mit.edu>
// MIT Media Lab
// November, 1999
//
#include <16F84.H>

// Configure PIC to use: HS clock, ENABLE Watchdog Timer, 
// no code protection, enable Power Up Timer
//
#fuses HS,WDT,NOPROTECT,PUT

// Tell compiler clock is 10MHz.  This is required for delay_ms()
// and for all serial I/O (such as printf(...).  These functions
// use software delay loops, so the compiler needs to know the
// processor speed.
//
#use DELAY(clock=10000000)

// Declare that we'll manually establish the data direction of
// each I/O pin on port B.
//
#use fast_io(B)

// Standard definitions for the irx2_1 board
//
#define RS232_XMT       PIN_B1  // (output) RS232 serial transmit
#define RED_LED         PIN_B2  // (output) Red LED (low true)
#define IR_LED          PIN_B3  // (output) Infrared LED (low true)
#define IR_SENSOR       PIN_B4  // (input) IR sensor (Sharp IS1U30)
#define RS232_RCV       PIN_B5  // (input) RS232 serial receive

// Macros to simplify I/O operations
//
#define RED_LED_ON      output_low(RED_LED)
#define RED_LED_OFF     output_high(RED_LED)
#define IR_LED_ON       output_low(IR_LED)
#define IR_LED_OFF      output_high(IR_LED)
#define IR_RECEIVED	(!input(IR_SENSOR))

// Default tri-state port direction bits: all PORT B bits are
// output except for IR_SENSOR (bit 4) and RC232_RCV (bit 5).
//
#define IRX_B_TRIS      0b00110000

// Inform printf() and friends of the desired baud rate 
// and which pins to use for serial I/O.
//
#use rs232(baud=9600, xmit=RS232_XMT, rcv=RS232_RCV)

void main() {
  // since we've declared #use fast_io(B) (above), we MUST 
  // include a call to set_tris_b() at startup.
  // 
  set_tris_b(IRX_B_TRIS);

  // set up prescaler on watchdog timer to bark after approx 576 mSec
  setup_counters(RTCC_INTERNAL, WDT_576MS);

  RED_LED_ON;			// reality check at startup
  delay_ms(200);
  RED_LED_OFF;
  restart_wdt();		// prevent wdt from firing too soon.

  while (1) {
    RED_LED_ON;			// turn on the led
    printf("Hello, world.\r\n"); // print to serial port
    RED_LED_OFF;		// turn off the led
    sleep();			// put PIC to sleep until WDT fires (576 mWSec)
  }
}