[PIC] Unable to display Tachometer and Speedometer at the same time

[rjwilliams]

I am using a pic16f877a, an EM-506 GPS module, and a 16x2 LCD to display the Speed Over Ground and using Timer 0 as the timer and Timer 1 as a counter to display RPM's. I can get the RPM's and speed to display individually but not at the same time. For the tachometer, I set the pre-scalar to 0x07 to create the longest delay possible prior to servicing the interrupt which increments a counter until the timer = 1 second at which point I multiply the value by 60 to create RPM's. I think the constant interrupting from Timer 0 effects the baud rate and prevents the GPS routine from running properly. Is there anyway to fix this? Also, by multiplying the value by 60 each time I get increments of 60 in the tachometer value, any work around to this? Thank you very much.

The LED is activated by port b change. When a button is pressed, the LED turns on indicating which routine is being run. This is the only way I can display it. The GPS_GetData andDisplayIt polls the RCIF flag and then begins to parse the nmea data string.

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
/****** Main Program Loop***************************************************/ 
    
while(1) 
    {
    
        while(LED2==0)
        {
        T1CONbits.TMR1ON = 0;                       // Enable counter
        INTCONbits.T0IE = 0;                        // Timer 0 Interrupt Enabled (Timer)
        GPS_GetDataAndDisplayIt();                  // Execute GPS Protocol
        WriteCmd_LCD(0x0C); 
        }
        if(LED2==1)
        {
        T1CONbits.TMR1ON = 1;                       // Enable counter
        INTCONbits.T0IE = 0;                        // Timer 0 Interrupt Enabled (Timer)
        __delay_ms(1000);   
                INTCONbits.T0IE = 0;                    // Timer 0 Interrupt Disabled (Timer)
                T1CONbits.TMR1ON = 0;                   // Stop counter
                rbcounter = TMR1L*60;                   // Pulse counter mins to secs
                TMR1L = 0x00;                           // Reset TMR1
                utoa(result,rbcounter,10);              // Convert rbcounter into string
                WriteCmd_LCD(0x02);                     // LCD home position
                ClearScreen_LCD();                      // Clear LCD
                MoveCursorToPosition(SecondLine);       // Second row
                WriteString_LCD("Tach: ");              // Display label
                WriteString_LCD(result);                // Display value
                WriteString_LCD(" RPM");                // Display units
                WriteCmd_LCD(0x0C); 
                rbcounter = 0;                          // Reset counter
                LED1 = 0;                               // LED off
                T1CONbits.TMR1ON = 1;                   // Start counter
                INTCONbits.T0IE = 1;                    // Timer 0 Interrupt Enabled (Timer)        
                }
        }           
    }   
    return 0; 
}

---