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33 * \brief AFSK modem hardware-specific definitions.
36 * \author Francesco Sacchi <batt@develer.com>
46 #include <avr/interrupt.h>
50 * Here we are using only one modem. If you need to receive
51 * from multiple modems, you need to define an array of contexts.
55 void hw_afsk_adcInit(int ch, Afsk *_ctx)
62 /* Set prescaler to clk/8 (2 MHz), CTC, top = ICR1 */
64 TCCR1B = BV(CS11) | BV(WGM13) | BV(WGM12);
65 /* Set max value to obtain a 9600Hz freq */
66 ICR1 = ((CPU_FREQ / 8) / 9600) - 1;
68 /* Set reference to AVCC (5V), select CH */
69 ADMUX = BV(REFS0) | ch;
75 /* Set autotrigger on Timer1 Input capture flag */
76 ADCSRB = BV(ADTS2) | BV(ADTS1) | BV(ADTS0);
77 /* Enable ADC, autotrigger, 1MHz, IRQ enabled */
78 /* We are using the ADC a bit out of specifications otherwise it's not fast enough for our
80 ADCSRA = BV(ADEN) | BV(ADSC) | BV(ADATE) | BV(ADIE) | BV(ADPS2);
87 * This is how you declare an ISR.
92 afsk_adc_isr(ctx, ((int16_t)((ADC) >> 2) - 128));
94 PORTD = afsk_dac_isr(ctx) & 0xF0;