103 lines
3.5 KiB
C
103 lines
3.5 KiB
C
|
|
#ifndef FSK_MODEM_H
|
|
#define FSK_MODEM_H
|
|
|
|
#include "config.h"
|
|
#include "hardware.h"
|
|
|
|
#include <cfg/compiler.h>
|
|
#include <io/kfile.h>
|
|
#include <struct/fifobuf.h>
|
|
|
|
|
|
#define SAMPLERATE 9600 // The rate at which we are sampling and synthesizing
|
|
#define BITRATE 1200 // The actual bitrate at baseband. This is the baudrate.
|
|
#define SAMPLESPERBIT (SAMPLERATE / BITRATE) // How many DAC/ADC samples constitute on bit (8).
|
|
|
|
typedef struct Hdlc
|
|
{
|
|
uint8_t demodulatedBits; // Incoming bitstream from demodulator
|
|
uint8_t bitIndex; // The current received bit in the current received byte
|
|
uint8_t currentByte; // The byte we're currently receiving
|
|
bool receiving; // Whether or not where actually receiving data (or just noise ;P)
|
|
} Hdlc;
|
|
|
|
#define RX_OVERRUN BV(0)
|
|
|
|
typedef struct Afsk
|
|
{
|
|
KFile fd;
|
|
|
|
// I/O hardware pins
|
|
int adcPin; // Pin for incoming signal
|
|
int dacPin; // Pin for outgoing signal
|
|
|
|
// General values
|
|
Hdlc hdlc; // We need a link control structure
|
|
uint16_t preambleLength; // Length of sync preamble
|
|
uint16_t tailLength; // Length of transmission tail
|
|
|
|
// Modulation values
|
|
uint8_t sampleIndex; // Current sample index for outgoing bit
|
|
uint8_t currentOutputByte; // Current byte to be modulated
|
|
uint8_t txBit; // Mask of current modulated bit
|
|
bool bitStuff; // Whether bitstuffing is allowed
|
|
|
|
uint8_t bitstuffCount; // Counter for bit-stuffing
|
|
|
|
uint16_t phaseAcc; // Phase accumulator
|
|
uint16_t phaseInc; // Phase increment per sample
|
|
|
|
FIFOBuffer txFifo; // FIFO for transmit data
|
|
uint8_t txBuf[CONFIG_AFSK_TX_BUFLEN]; // Actial data storage for said FIFO
|
|
|
|
volatile bool sending; // Set when modem is sending
|
|
|
|
// Demodulation values
|
|
FIFOBuffer delayFifo; // Delayed FIFO for frequency discrimination
|
|
int8_t delayBuf[SAMPLESPERBIT / 2 + 1];// Actual data storage for said FIFO
|
|
|
|
FIFOBuffer rxFifo; // FIFO for received data
|
|
uint8_t rxBuf[CONFIG_AFSK_RX_BUFLEN]; // Actual data storage for said FIFO
|
|
|
|
int16_t iirX[2]; // IIR Filter X cells
|
|
int16_t iirY[2]; // IIR Filter Y cells
|
|
|
|
uint8_t sampledBits; // Bits sampled by the demodulator (at ADC speed)
|
|
int8_t currentPhase; // Current phase of the demodulator
|
|
uint8_t actualBits; // Actual found bits at correct bitrate
|
|
|
|
volatile int status; // Status of the modem, 0 means OK
|
|
|
|
} Afsk;
|
|
|
|
// Explanation nessecary for this. BertOS uses an
|
|
// object-oriented approach for handling "file-like"
|
|
// transactions (yes, we are using C :P). What we are
|
|
// doing here is defining a specific "file type" for
|
|
// the standard KFile to identify the modem as a "file"
|
|
// that can be read from and written to.
|
|
#define KFT_AFSK MAKE_ID('F', 'S', 'K', 'M')
|
|
|
|
// We then make a macro that can "typecast" a generic
|
|
// KFile file-pointer to an Afsk "object". This lets
|
|
// other pieces of code read from and write to the AFSK
|
|
// "objects" buffers with the standard KFile operations.
|
|
// If this seems weird and confusing, check out the
|
|
// BertOS KFile explanation at:
|
|
// http://www.bertos.org/use/tutorial-front-page/drivers-kfile-interface
|
|
INLINE Afsk *AFSK_CAST(KFile *fd) {
|
|
// We need to assert that the what we are trying
|
|
// to read/write is actually an AFSK "object",
|
|
// identified by the KFT_AFSK constant
|
|
ASSERT(fd->_type == KFT_AFSK);
|
|
return (Afsk *)fd;
|
|
}
|
|
|
|
// Declare ISRs and initialization functions
|
|
void afsk_adc_isr(Afsk *af, int8_t sample);
|
|
uint8_t afsk_dac_isr(Afsk *af);
|
|
void afsk_init(Afsk *af, int adc_ch, int dac_ch);
|
|
|
|
#endif
|