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/* Name: modem.h
* Author: Jari Tulilahti
* Copyright: 2014 Rakettitiede Oy
* License: LGPLv3, see COPYING, and COPYING.LESSER -files for more info
*/
#ifndef MODEM_H_
#define MODEM_H_
#include <avr/interrupt.h>
#include <stdlib.h>
/* Modem ring buffer size must be power of 2 */
#define MODEM_BUFFER_SIZE 8
/* Modem defines */
#define MODEM_SYNC_LEN 42
#define MODEM_TIMER TCNT1L
#define MODEM_PCINT PCINT24
#define MODEM_PCMSK PCMSK3
#define MODEM_PCIE PCIE3
#define MODEM_PIN PA0
#define MODEM_DDR DDRA
/**
* Receive-only modem. Sets up a pin change interrupt on the modem pin
* and receives bytes using a simple protocol. Does not detect or correct
* transmission errors. Exposes a global modem object for convenience.
*/
class Modem {
private:
uint8_t buffer_head;
uint8_t buffer_tail;
uint8_t buffer[MODEM_BUFFER_SIZE];
void buffer_put(const uint8_t c);
public:
Modem() {};
/**
* Checks if there are unprocessed bytes in the modem receive buffer.
* @return number of unprocessed bytes
*/
uint8_t buffer_available(void);
/**
* Get next byte from modem receive buffer.
* @return next unprocessed byte (0 if the buffer is empty)
*/
uint8_t buffer_get(void);
/**
* Enable the modem. Turns on the input voltage divider on MODEM_PIN
* and enables the receive interrupt (MODEM_PCINT).
*/
void enable(void);
/**
* Disable the modem. Disables the receive interrupt and turns off
* the input voltage divider on MODEM_PIN.
*/
void disable(void);
/**
* Called by the pin change interrupt service routine whenever the
* modem pin is toggled. Detects sync pulses, receives bits and
* stores complete bytes in the buffer.
*
* Do not call this function yourself.
*/
void receive(void);
};
#endif /* MODEM_H_ */
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