Declare variables required for UART1 Handler

main.c

@@ -2,6 +2,11 @@
 #include <stdbool.h>
 #include "tm4c123gh6pm.h"
 
+#define MAX_FIELD_SIZE 100
+volatile char nmea_sentence[MAX_FIELD_SIZE];
+volatile uint8_t nmea_index = 0;
+volatile bool nmea_ready = false;
+
 void GPIO_PORT_F_init(void)
 {
     SYSCTL_RCGC2_R |= 0x00000020;             // ENABLE CLOCK TO GPIOF