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Reworked AFSK Struct

This commit is contained in:
Mark Qvist 2014-04-03 23:22:15 +02:00
parent 854d0abbe5
commit e76216875e
4 changed files with 115 additions and 153 deletions
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181
Modem/afsk.c
View File

@ -138,13 +138,7 @@ static bool hdlcParse(Hdlc *hdlc, bool bit, FIFOBuffer *fifo)
}
/**
* ADC ISR callback.
* This function has to be called by the ADC ISR when a sample of the configured
* channel is available.
* \param af Afsk context to operate on.
* \param curr_sample current sample from the ADC.
*/
void afsk_adc_isr(Afsk *af, int8_t curr_sample)
{
AFSK_STROBE_ON();
@ -165,63 +159,63 @@ void afsk_adc_isr(Afsk *af, int8_t curr_sample)
* through the CONFIG_AFSK_FILTER config variable.
*/
af->iir_x[0] = af->iir_x[1];
af->iirX[0] = af->iirX[1];
#if (CONFIG_AFSK_FILTER == AFSK_BUTTERWORTH)
af->iir_x[1] = ((int8_t)fifo_pop(&af->delay_fifo) * curr_sample) >> 2;
//af->iir_x[1] = ((int8_t)fifo_pop(&af->delay_fifo) * curr_sample) / 6.027339492;
af->iirX[1] = ((int8_t)fifo_pop(&af->delayFifo) * curr_sample) >> 2;
//af->iirX[1] = ((int8_t)fifo_pop(&af->delayFifo) * curr_sample) / 6.027339492;
#elif (CONFIG_AFSK_FILTER == AFSK_CHEBYSHEV)
af->iir_x[1] = ((int8_t)fifo_pop(&af->delay_fifo) * curr_sample) >> 2;
//af->iir_x[1] = ((int8_t)fifo_pop(&af->delay_fifo) * curr_sample) / 3.558147322;
af->iirX[1] = ((int8_t)fifo_pop(&af->delayFifo) * curr_sample) >> 2;
//af->iirX[1] = ((int8_t)fifo_pop(&af->delayFifo) * curr_sample) / 3.558147322;
#else
#error Filter type not found!
#endif
af->iir_y[0] = af->iir_y[1];
af->iirY[0] = af->iirY[1];
#if CONFIG_AFSK_FILTER == AFSK_BUTTERWORTH
/*
* This strange sum + shift is an optimization for af->iir_y[0] * 0.668.
* This strange sum + shift is an optimization for af->iirY[0] * 0.668.
* iir * 0.668 ~= (iir * 21) / 32 =
* = (iir * 16) / 32 + (iir * 4) / 32 + iir / 32 =
* = iir / 2 + iir / 8 + iir / 32 =
* = iir >> 1 + iir >> 3 + iir >> 5
*/
af->iir_y[1] = af->iir_x[0] + af->iir_x[1] + (af->iir_y[0] >> 1) + (af->iir_y[0] >> 3) + (af->iir_y[0] >> 5);
//af->iir_y[1] = af->iir_x[0] + af->iir_x[1] + af->iir_y[0] * 0.6681786379;
af->iirY[1] = af->iirX[0] + af->iirX[1] + (af->iirY[0] >> 1) + (af->iirY[0] >> 3) + (af->iirY[0] >> 5);
//af->iirY[1] = af->iirX[0] + af->iirX[1] + af->iirY[0] * 0.6681786379;
#elif CONFIG_AFSK_FILTER == AFSK_CHEBYSHEV
/*
* This should be (af->iir_y[0] * 0.438) but
* (af->iir_y[0] >> 1) is a faster approximation :-)
* This should be (af->iirY[0] * 0.438) but
* (af->iirY[0] >> 1) is a faster approximation :-)
*/
af->iir_y[1] = af->iir_x[0] + af->iir_x[1] + (af->iir_y[0] >> 1);
//af->iir_y[1] = af->iir_x[0] + af->iir_x[1] + af->iir_y[0] * 0.4379097269;
af->iirY[1] = af->iirX[0] + af->iirX[1] + (af->iirY[0] >> 1);
//af->iirY[1] = af->iirX[0] + af->iirX[1] + af->iirY[0] * 0.4379097269;
#endif
/* Save this sampled bit in a delay line */
af->sampled_bits <<= 1;
af->sampled_bits |= (af->iir_y[1] > 0) ? 1 : 0;
af->sampledBits <<= 1;
af->sampledBits |= (af->iirY[1] > 0) ? 1 : 0;
/* Store current ADC sample in the af->delay_fifo */
fifo_push(&af->delay_fifo, curr_sample);
/* Store current ADC sample in the af->delayFifo */
fifo_push(&af->delayFifo, curr_sample);
/* If there is an edge, adjust phase sampling */
if (EDGE_FOUND(af->sampled_bits))
if (EDGE_FOUND(af->sampledBits))
{
if (af->curr_phase < PHASE_THRES)
af->curr_phase += PHASE_INC;
if (af->currentPhase < PHASE_THRES)
af->currentPhase += PHASE_INC;
else
af->curr_phase -= PHASE_INC;
af->currentPhase -= PHASE_INC;
}
af->curr_phase += PHASE_BIT;
af->currentPhase += PHASE_BIT;
/* sample the bit */
if (af->curr_phase >= PHASE_MAX)
if (af->currentPhase >= PHASE_MAX)
{
af->curr_phase %= PHASE_MAX;
af->currentPhase %= PHASE_MAX;
/* Shift 1 position in the shift register of the found bits */
af->found_bits <<= 1;
af->actualBits <<= 1;
/*
* Determine bit value by reading the last 3 sampled bits.
@ -230,19 +224,19 @@ void afsk_adc_isr(Afsk *af, int8_t curr_sample)
* This algorithm presumes that there are 8 samples per bit.
*/
STATIC_ASSERT(SAMPLESPERBIT == 8);
uint8_t bits = af->sampled_bits & 0x07;
uint8_t bits = af->sampledBits & 0x07;
if (bits == 0x07 // 111, 3 bits set to 1
|| bits == 0x06 // 110, 2 bits
|| bits == 0x05 // 101, 2 bits
|| bits == 0x03 // 011, 2 bits
)
af->found_bits |= 1;
af->actualBits |= 1;
/*
* NRZI coding: if 2 consecutive bits have the same value
* a 1 is received, otherwise it's a 0.
*/
if (!hdlcParse(&af->hdlc, !EDGE_FOUND(af->found_bits), &af->rx_fifo))
if (!hdlcParse(&af->hdlc, !EDGE_FOUND(af->actualBits), &af->rxFifo))
af->status |= AFSK_RXFIFO_OVERRUN;
}
@ -254,14 +248,14 @@ static void afsk_txStart(Afsk *af)
{
if (!af->sending)
{
af->phase_inc = MARK_INC;
af->phase_acc = 0;
af->stuff_cnt = 0;
af->phaseInc = MARK_INC;
af->phaseAcc = 0;
af->bitstuffCount = 0;
af->sending = true;
af->preamble_len = DIV_ROUND(CONFIG_AFSK_PREAMBLE_LEN * BITRATE, 8000);
AFSK_DAC_IRQ_START(af->dac_ch);
af->preambleLength = DIV_ROUND(CONFIG_AFSK_PREAMBLE_LEN * BITRATE, 8000);
AFSK_DAC_IRQ_START(af->dacPin);
}
ATOMIC(af->trailer_len = DIV_ROUND(CONFIG_AFSK_TRAILER_LEN * BITRATE, 8000));
ATOMIC(af->tailLength = DIV_ROUND(CONFIG_AFSK_TRAILER_LEN * BITRATE, 8000));
}
#define BIT_STUFF_LEN 5
@ -282,14 +276,14 @@ uint8_t afsk_dac_isr(Afsk *af)
AFSK_STROBE_ON();
/* Check if we are at a start of a sample cycle */
if (af->sample_count == 0)
if (af->sampleIndex == 0)
{
if (af->tx_bit == 0)
if (af->txBit == 0)
{
/* We have just finished transimitting a char, get a new one. */
if (fifo_isempty(&af->tx_fifo) && af->trailer_len == 0)
if (fifo_isempty(&af->txFifo) && af->tailLength == 0)
{
AFSK_DAC_IRQ_STOP(af->dac_ch);
AFSK_DAC_IRQ_STOP(af->dacPin);
af->sending = false;
AFSK_STROBE_OFF();
return 0;
@ -300,58 +294,58 @@ uint8_t afsk_dac_isr(Afsk *af)
* If we have just finished sending an unstuffed byte,
* reset bitstuff counter.
*/
if (!af->bit_stuff)
af->stuff_cnt = 0;
if (!af->bitStuff)
af->bitstuffCount = 0;
af->bit_stuff = true;
af->bitStuff = true;
/*
* Handle preamble and trailer
*/
if (af->preamble_len == 0)
if (af->preambleLength == 0)
{
if (fifo_isempty(&af->tx_fifo))
if (fifo_isempty(&af->txFifo))
{
af->trailer_len--;
af->curr_out = HDLC_FLAG;
af->tailLength--;
af->currentOutputByte = HDLC_FLAG;
}
else
af->curr_out = fifo_pop(&af->tx_fifo);
af->currentOutputByte = fifo_pop(&af->txFifo);
}
else
{
af->preamble_len--;
af->curr_out = HDLC_FLAG;
af->preambleLength--;
af->currentOutputByte = HDLC_FLAG;
}
/* Handle char escape */
if (af->curr_out == AX25_ESC)
if (af->currentOutputByte == AX25_ESC)
{
if (fifo_isempty(&af->tx_fifo))
if (fifo_isempty(&af->txFifo))
{
AFSK_DAC_IRQ_STOP(af->dac_ch);
AFSK_DAC_IRQ_STOP(af->dacPin);
af->sending = false;
AFSK_STROBE_OFF();
return 0;
}
else
af->curr_out = fifo_pop(&af->tx_fifo);
af->currentOutputByte = fifo_pop(&af->txFifo);
}
else if (af->curr_out == HDLC_FLAG || af->curr_out == HDLC_RESET)
else if (af->currentOutputByte == HDLC_FLAG || af->currentOutputByte == HDLC_RESET)
/* If these chars are not escaped disable bit stuffing */
af->bit_stuff = false;
af->bitStuff = false;
}
/* Start with LSB mask */
af->tx_bit = 0x01;
af->txBit = 0x01;
}
/* check for bit stuffing */
if (af->bit_stuff && af->stuff_cnt >= BIT_STUFF_LEN)
if (af->bitStuff && af->bitstuffCount >= BIT_STUFF_LEN)
{
/* If there are more than 5 ones in a row insert a 0 */
af->stuff_cnt = 0;
af->bitstuffCount = 0;
/* switch tone */
af->phase_inc = SWITCH_TONE(af->phase_inc);
af->phaseInc = SWITCH_TONE(af->phaseInc);
}
else
{
@ -359,14 +353,14 @@ uint8_t afsk_dac_isr(Afsk *af)
* NRZI: if we want to transmit a 1 the modulated frequency will stay
* unchanged; with a 0, there will be a change in the tone.
*/
if (af->curr_out & af->tx_bit)
if (af->currentOutputByte & af->txBit)
{
/*
* Transmit a 1:
* - Stay on the previous tone
* - Increase bit stuff counter
*/
af->stuff_cnt++;
af->bitstuffCount++;
}
else
{
@ -375,23 +369,23 @@ uint8_t afsk_dac_isr(Afsk *af)
* - Reset bit stuff counter
* - Switch tone
*/
af->stuff_cnt = 0;
af->phase_inc = SWITCH_TONE(af->phase_inc);
af->bitstuffCount = 0;
af->phaseInc = SWITCH_TONE(af->phaseInc);
}
/* Go to the next bit */
af->tx_bit <<= 1;
af->txBit <<= 1;
}
af->sample_count = DAC_SAMPLESPERBIT;
af->sampleIndex = DAC_SAMPLESPERBIT;
}
/* Get new sample and put it out on the DAC */
af->phase_acc += af->phase_inc;
af->phase_acc %= SIN_LEN;
af->phaseAcc += af->phaseInc;
af->phaseAcc %= SIN_LEN;
af->sample_count--;
af->sampleIndex--;
AFSK_STROBE_OFF();
return sinSample(af->phase_acc);
return sinSample(af->phaseAcc);
}
@ -401,7 +395,7 @@ static size_t afsk_read(KFile *fd, void *_buf, size_t size)
uint8_t *buf = (uint8_t *)_buf;
#if CONFIG_AFSK_RXTIMEOUT == 0
while (size-- && !fifo_isempty_locked(&af->rx_fifo))
while (size-- && !fifo_isempty_locked(&af->rxFifo))
#else
while (size--)
#endif
@ -410,7 +404,7 @@ static size_t afsk_read(KFile *fd, void *_buf, size_t size)
ticks_t start = timer_clock();
#endif
while (fifo_isempty_locked(&af->rx_fifo))
while (fifo_isempty_locked(&af->rxFifo))
{
cpu_relax();
#if CONFIG_AFSK_RXTIMEOUT != -1
@ -419,7 +413,7 @@ static size_t afsk_read(KFile *fd, void *_buf, size_t size)
#endif
}
*buf++ = fifo_pop_locked(&af->rx_fifo);
*buf++ = fifo_pop_locked(&af->rxFifo);
}
return buf - (uint8_t *)_buf;
@ -432,10 +426,10 @@ static size_t afsk_write(KFile *fd, const void *_buf, size_t size)
while (size--)
{
while (fifo_isfull_locked(&af->tx_fifo))
while (fifo_isfull_locked(&af->txFifo))
cpu_relax();
fifo_push_locked(&af->tx_fifo, *buf++);
fifo_push_locked(&af->txFifo, *buf++);
afsk_txStart(af);
}
@ -465,33 +459,26 @@ static void afsk_clearerr(KFile *fd)
ATOMIC(af->status = 0);
}
/**
* Initialize an AFSK1200 modem.
* \param af Afsk context to operate on.
* \param adc_ch ADC channel used by the demodulator.
* \param dac_ch DAC channel used by the modulator.
*/
void afsk_init(Afsk *af, int adc_ch, int dac_ch)
void afsk_init(Afsk *af, int adcPin, int dacPin)
{
#if CONFIG_AFSK_RXTIMEOUT != -1
MOD_CHECK(timer);
#endif
memset(af, 0, sizeof(*af));
af->adc_ch = adc_ch;
af->dac_ch = dac_ch;
af->adcPin = adcPin;
af->dacPin = dacPin;
fifo_init(&af->delay_fifo, (uint8_t *)af->delay_buf, sizeof(af->delay_buf));
fifo_init(&af->rx_fifo, af->rx_buf, sizeof(af->rx_buf));
fifo_init(&af->delayFifo, (uint8_t *)af->delay_buf, sizeof(af->delay_buf));
fifo_init(&af->rxFifo, af->rx_buf, sizeof(af->rx_buf));
/* Fill sample FIFO with 0 */
for (int i = 0; i < SAMPLESPERBIT / 2; i++)
fifo_push(&af->delay_fifo, 0);
fifo_push(&af->delayFifo, 0);
fifo_init(&af->tx_fifo, af->tx_buf, sizeof(af->tx_buf));
fifo_init(&af->txFifo, af->tx_buf, sizeof(af->tx_buf));
AFSK_ADC_INIT(adc_ch, af);
AFSK_DAC_INIT(dac_ch, af);
AFSK_ADC_INIT(adcPin, af);
AFSK_DAC_INIT(dacPin, af);
AFSK_STROBE_INIT();
//LOG_INFO("MARK_INC %d, SPACE_INC %d\n", MARK_INC, SPACE_INC);
@ -501,5 +488,5 @@ void afsk_init(Afsk *af, int adc_ch, int dac_ch)
af->fd.flush = afsk_flush;
af->fd.error = afsk_error;
af->fd.clearerr = afsk_clearerr;
af->phase_inc = MARK_INC;
af->phaseInc = MARK_INC;
}

81
Modem/afsk.h
View File

@ -26,74 +26,49 @@ typedef struct Hdlc
typedef struct Afsk
{
// I/O hardware pins
int adcPin; // Pin for incoming signal
int dacPin; // Pin for outgoing signal
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
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 sample_index; // Current sample index for outgoing bit
uint8_t currentOutputByte; // Current byte to be modulated
uint8_t txBit; // Mask of current modulated bit
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
uint8_t bitstuffCount; // Counter for bit-stuffing
uint16_t phaseAcc; // Phase accumulator
uint16_t phaseInc; // Phase increment per sample
uint16_t phaseAcc; // Phase accumulator
uint16_t phaseInc; // Phase increment per sample
FIFOBuffer txFifo; // FIFO for transmit data
uint8_t txBuffer[TX_BUFLEN];// Actial data storage for said FIFO
FIFOBuffer txFifo; // FIFO for transmit data
uint8_t tx_buf[CONFIG_AFSK_TX_BUFLEN]; // Actial data storage for said FIFO
volatile bool sending; // Set when modem is sending
volatile bool sending; // Set when modem is sending
// Demodulation values
FIFOBuffer delayFifo; // Delayed FIFO for frequency discrimination
int8_t delayBuffer[5]; // Actual data storage for said FIFO
FIFOBuffer delayFifo; // Delayed FIFO for frequency discrimination
int8_t delay_buf[SAMPLESPERBIT / 2 + 1];// Actual data storage for said FIFO
FIFOBuffer rxFifo; // FIFO for received data
uint8_t rxBuffer[RX_BUFLEN];// Actual data storage for said FIFO
FIFOBuffer rxFifo; // FIFO for received data
uint8_t rx_buf[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
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
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
volatile int status; // Status of the modem, 0 means OK
/*
KFile fd;
int adc_ch;
int dac_ch;
uint8_t sample_count;
uint8_t curr_out;
uint8_t tx_bit;
bool bit_stuff;
uint8_t stuff_cnt;
uint16_t phase_acc;
uint16_t phase_inc;
FIFOBuffer delay_fifo;
int8_t delay_buf[SAMPLESPERBIT / 2 + 1];
FIFOBuffer rx_fifo;
uint8_t rx_buf[CONFIG_AFSK_RX_BUFLEN];
FIFOBuffer tx_fifo;
uint8_t tx_buf[CONFIG_AFSK_TX_BUFLEN];
int16_t iir_x[2];
int16_t iir_y[2];
uint8_t sampled_bits;
int8_t curr_phase;
uint8_t found_bits;
volatile bool sending;
volatile int status;
Hdlc hdlc;
uint16_t preamble_len;
uint16_t trailer_len;
*/
} Afsk;
#define KFT_AFSK MAKE_ID('F', 'S', 'K', 'M')

4
Modem/main.c
View File

@ -34,8 +34,8 @@ int main(void)
while (1)
{
if (!fifo_isempty(&afsk.rx_fifo)) {
char c = fifo_pop(&afsk.rx_fifo);
if (!fifo_isempty(&afsk.rxFifo)) {
char c = fifo_pop(&afsk.rxFifo);
kprintf("%c", c);
}
}

2
buildrev.h
View File

@ -1,2 +1,2 @@
#define VERS_BUILD 45
#define VERS_BUILD 49
#define VERS_HOST "vixen"