read time from gps

code/src/main.c

@@ -4,6 +4,7 @@
 #include <util/delay.h>
 #include <avr/interrupt.h>		//interrupts
 #include <stdlib.h>
+#include <string.h>
 #include "pinout.h"
 #include "print.h"
 #include "adc.h"
@@ -11,6 +12,7 @@
 #include "i2cmaster.h"
 #include "DS3231.h"
 
+#define RX_INPUT_BUFFER_SIZE 92
 
 /*README
    DIP1 aktiviert Röhren-Schaltregler
@@ -30,11 +32,32 @@ void check_buttons(void);
 void setup(void);
 void set_PWM_duty(int dutycycle);
 
+uint8_t parse_nmea_gps(char input_string[RX_INPUT_BUFFER_SIZE], uint8_t output_buffer[3]){
+    char* token = strsep(&input_string, ",");
+    if(!strcmp("$GPRMC", token)){
+        char* time = strsep(&input_string, ",");
+        if(!strlen(time)){
+            // no valid time available
+            return -1;
+        }
+
+        // craft bcd values
+        output_buffer[0]  = (time[0] - 48) << 4;
+        output_buffer[0] |= time[1] - 48;
+
+        output_buffer[1]  = (time[2] - 48) << 4;
+        output_buffer[1] |= time[3] - 48;
+
+        output_buffer[2]  = (time[4] - 48) << 4;
+        output_buffer[2] |= time[5] - 48;
+
+        return 0;
+    }
+}
+
 int main(void){
   setup();
 
-  printf("test\n\r");
-
   while(1){
  	_delay_ms(500);
  	
@@ -154,10 +177,10 @@ void setup(){
   TCCR1B = (0 << WGM02);
 
 
-  //Prescaler von 1024
-  TCCR1B |= (1 << CS02) |
-            (0 << CS01) |
-            (1 << CS00) ;
+  ////Prescaler von 1024
+  //TCCR1B |= (1 << CS02) |
+  //          (0 << CS01) |
+  //          (1 << CS00) ;
 
 
   //Output compare Regsiter (Setzt Zeit bei der Interrupt auslösen soll)
@@ -186,6 +209,12 @@ void setup(){
 
 
 }
+
+void set_PWM_duty(int dutycycle){
+	 OCR2A = dutycycle;
+ }
+
+
 //Timer 1 Interrupt
 ISR (TIMER1_OVF_vect)    // Timer1 ISR
 {
@@ -218,63 +247,23 @@ ISR(INT1_vect) {
 }
 
 
-ISR (USART0_RX_vect){
-	/*
-//while ( !(UCSR0A & (1<<RXC0)) ){};	//RXC = Recive complete
-	char uart_Buffer[500];
-	char time_string[6];
-	char sat_string[2];
-	sat_string[0]='1';
-	sat_string[1]= '1';
-
-	for(int k = 0; k < 6; k++){
-		time_string[k] = '8';
-	}
-	int i = 0;
-
-    while(UDR0 != '\r' && i < 500){
-		uart_Buffer[i] = UDR0;
-		i++;
-			PORTB ^=STATUS_LED_B;	
-			
-
-	}
-	
-	for(int j = 0; j < 500; j++){
-		
-		//if(uart_Buffer[j] == '$'){
-			if(uart_Buffer[j+1] == 'G'){
-				if(uart_Buffer[j+2] == 'P'){
-					if(uart_Buffer[j+3] == 'Z'){
-						if(uart_Buffer[j+4] == 'D'){
-							if(uart_Buffer[j+5] == 'A'){
-									//j++;
-									
-									sat_string[0] = uart_Buffer[1];
-									sat_string[1] = uart_Buffer[100];
-									
-									//time_string[0] = uart_Buffer[j+36];
-									//time_string[1] = uart_Buffer[j+37];
-									//time_string[2] = uart_Buffer[j+8];
-									//time_string[3] = uart_Buffer[j+9];
-									//time_string[5] = uart_Buffer[j+10];
-									//time_string[6] = uart_Buffer[j+11];
-							}
-						}
-					}
-				}
-			}
-	//	}
-	
-	}
- 
-  
-print_String(sat_string);
+ISR(USART0_RX_vect)
+{
+    static char async_input_buffer[RX_INPUT_BUFFER_SIZE];
+    static uint8_t async_buffer_pointer = 0;
 
-*/
+    uint8_t data = UART_DATA_REG;
+    if(!(data == '\n' || data == '\r')){
+        async_input_buffer[async_buffer_pointer]=data;
+        async_buffer_pointer++;
+    }
+    else if(async_buffer_pointer>0){
+        async_input_buffer[async_buffer_pointer] = 0; // Null terminate string
+        async_buffer_pointer=0;
+        PORTB ^=STATUS_LED_C;
+        uint8_t test[3];
+        if(!parse_nmea_gps(async_input_buffer, test))
+            printf("parse: %x %x %x\n\r", test[0], test[1], test[2]); 
+    }
 }
 
-void set_PWM_duty(int dutycycle){
-	 OCR2A = dutycycle;
- }
-