Add date to GPS data, captured from GPRMC packet.

Pull the date out of the GPS stream and send it over the telemetry
link and write it to the eeprom.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 60 insertions, 7 deletions

diff --git a/src/ao_gps_skytraq.c b/src/ao_gps_skytraq.c
index cd5f78b9..b2eef04b 100644
--- a/src/ao_gps_skytraq.c
+++ b/src/ao_gps_skytraq.c
@@ -19,9 +19,9 @@
 #include "ao.h"
 #endif
 
-#define AO_GPS_LEADER		3
+#define AO_GPS_LEADER		2
 
-static const char ao_gps_header[] = "GPG";
+static const char ao_gps_header[] = "GP";
 
 __xdata uint8_t ao_gps_mutex;
 static __xdata char ao_gps_char;
@@ -32,6 +32,7 @@ __xdata struct ao_gps_data	ao_gps_data;
 __xdata struct ao_gps_tracking_data	ao_gps_tracking_data;
 
 static __xdata struct ao_gps_data		ao_gps_next;
+static __xdata uint8_t				ao_gps_date_flags;
 static __xdata struct ao_gps_tracking_data	ao_gps_tracking_next;
 
 static const char ao_gps_config[] = {
@@ -181,7 +182,7 @@ ao_gps_parse_flag(char no_c, char yes_c) __reentrant
 void
 ao_gps(void) __reentrant
 {
-	char	c;
+	char	a, c;
 	uint8_t	i;
 
 	ao_serial_set_speed(AO_SERIAL_SPEED_9600);
@@ -198,7 +199,7 @@ ao_gps(void) __reentrant
 		ao_gps_cksum = 0;
 		ao_gps_error = 0;
 
-		/* Skip anything other than GPG */
+		/* Skip anything other than GP */
 		for (i = 0; i < AO_GPS_LEADER; i++) {
 			ao_gps_lexchar();
 			if (ao_gps_char != ao_gps_header[i])
@@ -209,6 +210,8 @@ ao_gps(void) __reentrant
 
 		/* pull the record identifier characters off the link */
 		ao_gps_lexchar();
+		a = ao_gps_char;
+		ao_gps_lexchar();
 		c = ao_gps_char;
 		ao_gps_lexchar();
 		i = ao_gps_char;
@@ -216,7 +219,7 @@ ao_gps(void) __reentrant
 		if (ao_gps_char != ',')
 			continue;
 
-		if (c == (uint8_t) 'G' && i == (uint8_t) 'A') {
+		if (a == (uint8_t) 'G' && c == (uint8_t) 'G' && i == (uint8_t) 'A') {
 			/* Now read the data into the gps data record
 			 *
 			 * $GPGGA,025149.000,4528.1723,N,12244.2480,W,1,05,2.0,103.5,M,-19.5,M,,0000*66
@@ -245,7 +248,7 @@ ao_gps(void) __reentrant
 			 *	   *66		checksum
 			 */
 
-			ao_gps_next.flags = AO_GPS_RUNNING;
+			ao_gps_next.flags = AO_GPS_RUNNING | ao_gps_date_flags;
 			ao_gps_next.hour = ao_gps_decimal(2);
 			ao_gps_next.minute = ao_gps_decimal(2);
 			ao_gps_next.second = ao_gps_decimal(2);
@@ -290,7 +293,7 @@ ao_gps(void) __reentrant
 				ao_mutex_put(&ao_gps_mutex);
 				ao_wakeup(&ao_gps_data);
 			}
-		} else if (c == (uint8_t) 'S' && i == (uint8_t) 'V') {
+		} else if (a == (uint8_t) 'G' && c == (uint8_t) 'S' && i == (uint8_t) 'V') {
 			uint8_t	done;
 			/* Now read the data into the GPS tracking data record
 			 *
@@ -345,6 +348,56 @@ ao_gps(void) __reentrant
 				ao_mutex_put(&ao_gps_mutex);
 				ao_wakeup(&ao_gps_tracking_data);
 			}
+		} else if (a == (uint8_t) 'R' && c == (uint8_t) 'M' && i == (uint8_t) 'C') {
+			/* Parse the RMC record to read out the current date */
+
+			/* $GPRMC,111636.932,A,2447.0949,N,12100.5223,E,000.0,000.0,030407,,,A*61
+			 *
+			 * Recommended Minimum Specific GNSS Data
+			 *
+			 *	111636.932	UTC time 11:16:36.932
+			 *	A		Data Valid (V = receiver warning)
+			 *	2447.0949	Latitude
+			 *	N		North/south indicator
+			 *	12100.5223	Longitude
+			 *	E		East/west indicator
+			 *	000.0		Speed over ground
+			 *	000.0		Course over ground
+			 *	030407		UTC date (ddmmyy format)
+			 *	A		Mode indicator:
+			 *			N = data not valid
+			 *			A = autonomous mode
+			 *			D = differential mode
+			 *			E = estimated (dead reckoning) mode
+			 *			M = manual input mode
+			 *			S = simulator mode
+			 *	61		checksum
+			 */
+			ao_gps_skip_field();
+			for (i = 0; i < 8; i++) {
+				ao_gps_lexchar();
+				ao_gps_skip_field();
+			}
+			a = ao_gps_decimal(2);
+			c = ao_gps_decimal(2);
+			i = ao_gps_decimal(2);
+			/* Skip remaining fields */
+			while (ao_gps_char != '*' && ao_gps_char != '\n' && ao_gps_char != '\r') {
+				ao_gps_lexchar();
+				ao_gps_skip_field();
+			}
+			if (ao_gps_char == '*') {
+				uint8_t cksum = ao_gps_cksum ^ '*';
+				if (cksum != ao_gps_hex(2))
+					ao_gps_error = 1;
+			} else
+				ao_gps_error = 1;
+			if (!ao_gps_error) {
+				ao_gps_next.year = i;
+				ao_gps_next.month = c;
+				ao_gps_next.day = a;
+				ao_gps_date_flags = AO_GPS_DATE_VALID;
+			}
 		}
 	}
 }