X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fnet%2Fafsk.c;h=e516a3f32b854bf23d813ebcc70600afd1eca34d;hb=441c294a809638c22c77ae37c8e7bb57cf57f126;hp=c73cf8585a47aa0e218605c33a2112268f57a5b6;hpb=e1aa79e276934cbaceeb77a85b945074e3c1bbc8;p=bertos.git

diff --git a/bertos/net/afsk.c b/bertos/net/afsk.c
index c73cf858..e516a3f3 100644
--- a/bertos/net/afsk.c
+++ b/bertos/net/afsk.c
@@ -37,6 +37,8 @@
  */
 
 #include "afsk.h"
+#include <net/ax25.h>
+
 #include "cfg/cfg_afsk.h"
 #include "hw/hw_afsk.h"
 
@@ -149,6 +151,7 @@ static uint8_t tx_buf[CONFIG_AFSK_TX_BUFLEN];
 
 static int16_t iir_x[2];
 static int16_t iir_y[2];
+
 static uint8_t sampled_bits;
 static uint8_t found_bits;
 static uint8_t demod_bits;
@@ -161,6 +164,9 @@ static uint8_t hdlc_bit_idx;
 #define BIT_DIFFER(bitline1, bitline2) (((bitline1) ^ (bitline2)) & 0x01)
 #define EDGE_FOUND(bitline)            BIT_DIFFER((bitline), (bitline) >> 1)
 
+static uint16_t preamble_len;
+static uint16_t trailer_len;
+
 static void hdlc_parse(bool bit)
 {
 	demod_bits <<= 1;
@@ -169,13 +175,14 @@ static void hdlc_parse(bool bit)
 	/* HDLC Flag */
 	if (demod_bits == HDLC_FLAG)
 	{
-		if (!fifo_isfull_locked(&rx_fifo))
+		if (!fifo_isfull(&rx_fifo))
 		{
 			fifo_push(&rx_fifo, HDLC_FLAG);
 			hdlc_rxstart = true;
 		}
 		else
 			hdlc_rxstart = false;
+
 		hdlc_currchar = 0;
 		hdlc_bit_idx = 0;
 		return;
@@ -202,13 +209,15 @@ static void hdlc_parse(bool bit)
 	{
 		if ((hdlc_currchar == HDLC_FLAG
 			|| hdlc_currchar == HDLC_RESET
-			|| hdlc_currchar == AFSK_ESC)
-			&& !fifo_isfull_locked(&rx_fifo))
-			fifo_push(&rx_fifo, AFSK_ESC);
-		else
-			hdlc_rxstart = false;
+			|| hdlc_currchar == AX25_ESC))
+		{
+			if (!fifo_isfull(&rx_fifo))
+				fifo_push(&rx_fifo, AX25_ESC);
+			else
+				hdlc_rxstart = false;
+		}
 
-		if (!fifo_isfull_locked(&rx_fifo))
+		if (!fifo_isfull(&rx_fifo))
 			fifo_push(&rx_fifo, hdlc_currchar);
 		else
 			hdlc_rxstart = false;
@@ -236,23 +245,44 @@ DEFINE_AFSK_ADC_ISR()
 
 	/*
 	 * Frequency discrimination is achieved by simply multiplying
-	 * the sample with a delayed sample of (bits per sample) / 2.
-	 * Then the signal is lowpass filtered with a first order, 600 Hz
-	 * Butterworth filter.
+	 * the sample with a delayed sample of (samples per bit) / 2.
+	 * Then the signal is lowpass filtered with a first order,
+	 * 600 Hz filter. The filter implementation is selectable
+	 * through the CONFIG_AFSK_FILTER config variable.
 	 */
 
 	iir_x[0] = iir_x[1];
-	iir_x[1] = ((int8_t)fifo_pop(&delay_fifo) * curr_sample) >> 2;
+
+	#if (CONFIG_AFSK_FILTER == AFSK_BUTTERWORTH)
+		iir_x[1] = ((int8_t)fifo_pop(&delay_fifo) * curr_sample) >> 2;
+		//iir_x[1] = ((int8_t)fifo_pop(&delay_fifo) * curr_sample) / 6.027339492;
+	#elif (CONFIG_AFSK_FILTER == AFSK_CHEBYSHEV)
+		iir_x[1] = ((int8_t)fifo_pop(&delay_fifo) * curr_sample) >> 2;
+		//iir_x[1] = ((int8_t)fifo_pop(&delay_fifo) * curr_sample) / 3.558147322;
+	#else
+		#error Filter type not found!
+	#endif
+
 	iir_y[0] = iir_y[1];
 
-	/*
-	 * This strange sum + shift is an optimization for iir_y[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
-	 */
-	iir_y[1] = iir_x[0] + iir_x[1] + (iir_y[0] >> 1) + (iir_y[0] >> 3) + (iir_y[0] >> 5);
+	#if CONFIG_AFSK_FILTER == AFSK_BUTTERWORTH
+		/*
+		 * This strange sum + shift is an optimization for iir_y[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
+		 */
+		iir_y[1] = iir_x[0] + iir_x[1] + (iir_y[0] >> 1) + (iir_y[0] >> 3) + (iir_y[0] >> 5);
+		//iir_y[1] = iir_x[0] + iir_x[1] + iir_y[0] * 0.6681786379;
+	#elif CONFIG_AFSK_FILTER == AFSK_CHEBYSHEV
+		/*
+		 * This should be (iir_y[0] * 0.438) but
+		 * (iir_y[0] >> 1) is a faster approximation :-)
+		 */
+		iir_y[1] = iir_x[0] + iir_x[1] + (iir_y[0] >> 1);
+		//iir_y[1] = iir_x[0] + iir_x[1] + iir_y[0] * 0.4379097269;
+	#endif
 
 	/* Save this sampled bit in a delay line */
 	sampled_bits <<= 1;
@@ -280,10 +310,17 @@ DEFINE_AFSK_ADC_ISR()
 		found_bits <<= 1;
 
 		/*
-		 * TODO: maybe a better algorithm to find the sample bit
-		 * other than reading the last one.
+		 * Determine bit value by reading the last 3 sampled bits.
+		 * If the number of ones is two or greater, the bit value is a 1,
+		 * otherwise is a 0.
 		 */
-		found_bits |= sampled_bits & 1;
+		uint8_t bits = sampled_bits & 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
+		)
+			found_bits |= 1;
 
 		/*
 		 * NRZI coding: if 2 consecutive bits have the same value
@@ -292,7 +329,9 @@ DEFINE_AFSK_ADC_ISR()
 		hdlc_parse(!EDGE_FOUND(found_bits));
 	}
 
+
 	AFSK_STROBE_OFF();
+	AFSK_ADC_IRQ_END();
 }
 
 /* True while modem sends data */
@@ -306,8 +345,10 @@ static void afsk_txStart(void)
 		phase_acc = 0;
 		stuff_cnt = 0;
 		sending = true;
+		preamble_len = DIV_ROUND(CONFIG_AFSK_PREAMBLE_LEN * BITRATE, 8000);
 		AFSK_DAC_IRQ_START();
 	}
+	ATOMIC(trailer_len  = DIV_ROUND(CONFIG_AFSK_TRAILER_LEN  * BITRATE, 8000));
 }
 
 #define BIT_STUFF_LEN 5
@@ -322,10 +363,11 @@ DEFINE_AFSK_DAC_ISR()
 		if (tx_bit == 0)
 		{
 			/* We have just finished transimitting a char, get a new one. */
-			if (fifo_isempty(&tx_fifo))
+			if (fifo_isempty(&tx_fifo) && trailer_len == 0)
 			{
 				AFSK_DAC_IRQ_STOP();
 				sending = false;
+				AFSK_DAC_IRQ_END();
 				return;
 			}
 			else
@@ -338,15 +380,34 @@ DEFINE_AFSK_DAC_ISR()
 					stuff_cnt = 0;
 
 				bit_stuff = true;
-				curr_out = fifo_pop(&tx_fifo);
+
+				/*
+				 * Handle preamble and trailer
+				 */
+				if (preamble_len == 0)
+				{
+					if (fifo_isempty(&tx_fifo))
+					{
+						trailer_len--;
+						curr_out = HDLC_FLAG;
+					}
+					else
+						curr_out = fifo_pop(&tx_fifo);
+				}
+				else
+				{
+					preamble_len--;
+					curr_out = HDLC_FLAG;
+				}
 
 				/* Handle char escape */
-				if (curr_out == AFSK_ESC)
+				if (curr_out == AX25_ESC)
 				{
 					if (fifo_isempty(&tx_fifo))
 					{
 						AFSK_DAC_IRQ_STOP();
 						sending = false;
+						AFSK_DAC_IRQ_END();
 						return;
 					}
 					else
@@ -406,6 +467,7 @@ DEFINE_AFSK_DAC_ISR()
 
 	AFSK_SET_DAC(sin_sample(phase_acc));
 	sample_count--;
+	AFSK_DAC_IRQ_END();
 }
 
 
@@ -423,7 +485,7 @@ static size_t afsk_read(UNUSED_ARG(KFile *, fd), void *_buf, size_t size)
 		ticks_t start = timer_clock();
 		#endif
 
-		do
+		while (fifo_isempty_locked(&rx_fifo));
 		{
 			cpu_relax();
 			#if CONFIG_AFSK_RXTIMEOUT != -1
@@ -431,7 +493,6 @@ static size_t afsk_read(UNUSED_ARG(KFile *, fd), void *_buf, size_t size)
 				return buf - (uint8_t *)_buf;
 			#endif
 		}
-		while (fifo_isempty_locked(&rx_fifo));
 
 		*buf++ = fifo_pop_locked(&rx_fifo);
 	}
@@ -479,6 +540,7 @@ void afsk_init(Afsk *af)
 	fifo_init(&tx_fifo, tx_buf, sizeof(tx_buf));
 
 	AFSK_ADC_INIT();
+	AFSK_STROBE_INIT();
 	kprintf("MARK_INC %d, SPACE_INC %d\n", MARK_INC, SPACE_INC);
 
 	memset(af, 0, sizeof(*af));