OpenModem/Modem/hw/hw_afsk.c

98 lines
2.7 KiB
C

/**
* \file
* <!--
* This file is part of BeRTOS.
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*
* \brief AFSK modem hardware-specific definitions.
*
*
* \author Francesco Sacchi <batt@develer.com>
*/
#include "hw_afsk.h"
#include <net/afsk.h>
#include <cpu/irq.h>
#include <avr/io.h>
#include <avr/interrupt.h>
/*
* Here we are using only one modem. If you need to receive
* from multiple modems, you need to define an array of contexts.
*/
static Afsk *ctx;
void hw_afsk_adcInit(int ch, Afsk *_ctx)
{
ctx = _ctx;
ASSERT(ch <= 5);
AFSK_STROBE_INIT();
AFSK_STROBE_OFF();
/* Set prescaler to clk/8 (2 MHz), CTC, top = ICR1 */
TCCR1A = 0;
TCCR1B = BV(CS11) | BV(WGM13) | BV(WGM12);
/* Set max value to obtain a 9600Hz freq */
ICR1 = ((CPU_FREQ / 8) / 9600) - 1;
/* Set reference to AVCC (5V), select CH */
ADMUX = BV(REFS0) | ch;
DDRC &= ~BV(ch);
PORTC &= ~BV(ch);
DIDR0 |= BV(ch);
/* Set autotrigger on Timer1 Input capture flag */
ADCSRB = BV(ADTS2) | BV(ADTS1) | BV(ADTS0);
/* Enable ADC, autotrigger, 1MHz, IRQ enabled */
/* We are using the ADC a bit out of specifications otherwise it's not fast enough for our
* purposes */
ADCSRA = BV(ADEN) | BV(ADSC) | BV(ADATE) | BV(ADIE) | BV(ADPS2);
}
bool hw_afsk_dac_isr;
/*
* This is how you declare an ISR.
*/
DECLARE_ISR(ADC_vect)
{
TIFR1 = BV(ICF1);
afsk_adc_isr(ctx, ((int16_t)((ADC) >> 2) - 128));
if (hw_afsk_dac_isr)
PORTD = afsk_dac_isr(ctx) & 0xF0;
else
PORTD = 128;
}