wiring.c

/*
  wiring.c - Wiring API Partial Implementation
  Part of Arduino / Wiring Lite

  Copyright (c) 2005 David A. Mellis

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General
  Public License along with this library; if not, write to the
  Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  Boston, MA  02111-1307  USA

  $Id: wiring.c,v 1.7 2005/05/28 21:04:15 mellis Exp $
*/

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/signal.h>
#include <avr/delay.h>
#include <stdio.h>
#include <stdarg.h>

#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif

// from Pascal's avrlib
#include "global.h"
//#include "a2d.h"
#include "timer.h"
#include "uart.h"

// timer.h #defines delay to be delay_us, we need to undefine
// it so our delay can be in milliseconds.
#undef delay

#include "BConstants.h"
#include "wiring.h"

// Get the hardware port of the given virtual pin number.  This comes from
// the pins_*.c file for the active board configuration.
int digitalPinToPort(int pin)
{
	return digital_pin_to_port[pin].port;
}

// Get the bit location within the hardware port of the given virtual pin.
// This comes from the pins_*.c file for the active board configuration.
int digitalPinToBit(int pin)
{
	return digital_pin_to_port[pin].bit;
}

int analogOutPinToPort(int pin)
{
	return analog_out_pin_to_port[pin].port;
}

int analogOutPinToBit(int pin)
{
	return analog_out_pin_to_port[pin].bit;
}

int analogInPinToBit(int pin)
{
	return analog_in_pin_to_port[pin].bit;
}

void pinMode(int pin, int mode)
{
	if (digitalPinToPort(pin) != NOT_A_PIN) {
		if (mode == INPUT)
			cbi(_SFR_IO8(port_to_mode[digitalPinToPort(pin)]), digitalPinToBit(pin));
		else
			sbi(_SFR_IO8(port_to_mode[digitalPinToPort(pin)]), digitalPinToBit(pin));
	}
}

void digitalWrite(int pin, int val)
{
	if (digitalPinToPort(pin) != NOT_A_PIN) {
		// If the pin that support PWM output, we need to turn it off
		// before doing a digital write.

		if (analogOutPinToBit(pin) == 1)
			timer1PWMAOff();

		if (analogOutPinToBit(pin) == 2)
			timer1PWMBOff();

		if (val == LOW)
			cbi(_SFR_IO8(port_to_output[digitalPinToPort(pin)]), digitalPinToBit(pin));
		else
			sbi(_SFR_IO8(port_to_output[digitalPinToPort(pin)]), digitalPinToBit(pin));
	}
}

int digitalRead(int pin)
{
	if (digitalPinToPort(pin) != NOT_A_PIN) {
		// If the pin that support PWM output, we need to turn it off
		// before getting a digital reading.

		if (analogOutPinToBit(pin) == 1)
			timer1PWMAOff();

		if (analogOutPinToBit(pin) == 2)
			timer1PWMBOff();

		return (_SFR_IO8(port_to_input[digitalPinToPort(pin)]) >> digitalPinToBit(pin)) & 0x01;
	}
	
	return LOW;
}

/*
int analogRead(int pin)
{
	unsigned long start_time = millis();
	int ch = analogInPinToBit(pin);
	volatile unsigned int low, high;

	//return a2dConvert10bit(ch);

	a2dSetChannel(ch);
	a2dStartConvert();

	// wait until the conversion is complete or we
	// time out.  without the timeout, this sometimes
	// becomes an infinite loop.  page 245 of the atmega8
	// datasheet says the conversion should take at most
	// 260 microseconds, so if two milliseconds have ticked
	// by, something's wrong.
	//while (!a2dIsComplete() && millis() - start_time < 50);
	while (!a2dIsComplete());

	// a2Convert10bit sometimes read ADCL and ADCH in the
	// wrong order (?) causing it to sometimes miss reading,
	// especially if called multiple times in rapid succession.
	//return a2dConvert10bit(ch);
	//return ADCW;
	low = ADCL;
	high = ADCH;

	return (high << 8) | low;
}
*/

int analogRead(int pin)
{
	unsigned int low, high, ch = analogInPinToBit(pin);

	// the low 4 bits of ADMUX select the ADC channel
	ADMUX = (ADMUX & (unsigned int) 0xf0) | (ch & (unsigned int) 0x0f);

	// without a delay, we seem to read from the wrong channel
	delay(1);

	// start the conversion
	sbi(ADCSRA, ADSC);

	// ADSC is cleared when the conversion finishes
	while (bit_is_set(ADCSRA, ADSC));

	// we have to read ADCL first; doing so locks both ADCL
	// and ADCH until ADCH is read.  reading ADCL second would
	// cause the results of each conversion to be discarded,
	// as ADCL and ADCH would be locked when it completed.
	low = ADCL;
	high = ADCH;

	// combine the two bytes
	return (high << 8) | low;
}

// Right now, PWM output only works on the pins with
// hardware support.  These are defined in the appropriate
// pins_*.c file.  For the rest of the pins, we default
// to digital output.
void analogWrite(int pin, int val)
{
	// We need to make sure the PWM output is enabled for those pins
	// that support it, as we turn it off when digitally reading or
	// writing with them.  Also, make sure the pin is in output mode
	// for consistenty with Wiring, which doesn't require a pinMode
	// call for the analog output pins.
	if (analogOutPinToBit(pin) == 1) {
		pinMode(pin, OUTPUT);
		timer1PWMAOn();
		timer1PWMASet(val);
	} else if (analogOutPinToBit(pin) == 2) {
		pinMode(pin, OUTPUT);
		timer1PWMBOn();
		timer1PWMBSet(val);
	} else if (val < 128)
		digitalWrite(pin, LOW);
	else
		digitalWrite(pin, HIGH);
}

void beginSerial(int baud)
{
	uartInit();
	uartSetBaudRate(baud);
}

void serialWrite(unsigned char c)
{
	uartSendByte(c);
}

void printMode(int mode)
{
	// do nothing, we only support serial printing, not lcd.
}

void uartSendString(unsigned char *str)
{
	while (*str)
		uartSendByte(*str++);
}

void print(const char *format, ...)
{
	char buf[256];
	va_list ap;
	
	va_start(ap, format);
	vsnprintf(buf, 256, format, ap);
	va_end(ap);
	
	uartSendString(buf);
}

unsigned long millis()
{
	// timer 0 increments every timer0GetPrescaler() cycles, and
	// overflows when it reaches 256.  we calculate the total
	// number of clock cycles, then divide by the number of clock
	// cycles per millisecond.
	return timer0GetOverflowCount() * timer0GetPrescaler() * 256L / F_CPU * 1000L;
}

void delay(unsigned long ms)
{
	timerPause(ms);
}

int main(void)
{
	sei();
	
	// timer 0 is used for millis() and delay()
	timer0Init();

	// timer 1 is used for the hardware pwm
	timer1Init();
	timer1SetPrescaler(TIMER_CLK_DIV1);
	timer1PWMInit(8);

	//a2dInit();
	//a2dSetPrescaler(ADC_PRESCALE_DIV128);

	// set a2d reference to AVCC (5 volts)
	cbi(ADMUX, REFS1);
	sbi(ADMUX, REFS0);

	// set a2d prescale factor to 128
	// 16 MHz / 128 = 125 KHz, inside the desired 50-200 KHz range.
	// XXX: this will not work properly for other clock speeds, and
	// this code should use F_CPU to determine the prescale factor.
	sbi(ADCSRA, ADPS2);
	sbi(ADCSRA, ADPS1);
	sbi(ADCSRA, ADPS0);

	// enable a2d conversions
	sbi(ADCSRA, ADEN);
	
	setup();
	
	for (;;)
		loop();
		
	return 0;
}