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--- code:interrupt_driven_nmea [2008/04/23 00:56] – laurenceb
+++ code:interrupt_driven_nmea [2013/04/18 20:00] (current) – Reports code isn't tested so just put a notice on there upu
@@ Line 1: / Line 1: @@
- This is a rather unconvensional approach to a NMEA parser - completely based on an ISR to parse the incoming bytes. It uses 2.2KB of code space and 44 bytes of RAM.
+**This code hasn't been tested and is believe not to work**
+This is a rather unconvensional approach to a NMEA parser - completely based on an ISR to parse the incoming bytes. It uses 1.9KB of code space and 44 bytes of RAM. Should run in less than 10us at 18MHz.
 <code c>#include "main.h"
 //global(s)
-extern gps_type gps;
+extern gps_type Gps;
 // Interrupt driven NMEA parser for Atmel AVR
 ISR(USART_RX_vect)				//UART interrupt on mega xx8 series
 {
@@ Line 17: / Line 20: @@
 	static u08 bufferindex;
 	static u08 pointcount;
+	static gps_type gps;
 	char c=UDR0;
 	switch(c)
@@ Line 120: / Line 124: @@
 			if(commacount==9)		//the heading
 			{
 				if(!pointcount)
 				{
@@ Line 128: / Line 132: @@
 				{
 					gps.heading=(float)atoi(buffer)*0.1;
-					gps.packetflag=TRUE;	//this is usually the last interesting part of the fix info to come through
+					toggle_pin;		//toggles pin D5 - flashing LED
+					if(!Gps.packetflag)	//main has unlocked the data
+					{
+						Gps.packetflag=TRUE;	//this is usually the last interesting part of the fix info to come through
+						Gps=gps;		//copy into the global variable
+					}
 				}
 			}
@@ Line 151: / Line 160: @@
 		 }
 	}
 }
 </code>