How to Program CCP1 Module in PIC16F877A (Capture Mode)

The following code demonstrate how to use CCP1 module in capture mode configuration.  The PIR1.CCP1IF flag is set when rising edge is detected on RC2/CCP1 pin. The code is written in “mikroC PRO for PIC v.6.6.3” IDE and simulation is done with Proteus 8.0 SP0. At the end of code, you can find complete project files for download.

Code in mikroC

// Tick Time (Sec) = (4 x prescalar)/Fosc
// prescalar 1:1
// Fosc = 20,000,000 Hz
// Tick Time (Sec) = 0.0000002
// direction signal
sbit CCP1_dir at TRISC.B2;
// function pro-type
void SendToUART(unsigned long ccpr1);
void CaptureModeConfig(void);
void T1Config(void);
void main(void)
{
unsigned long ccpr1 = 0;
UART1_Init(115200);
// Capture Mode configration
CaptureModeConfig();
// timer-1 configration
T1Config();
while(1)
{
while(PIR1.CCP1IF == 0);
PIR1.CCP1IF = 0; // clear CCP Interrupt Flag bit
TMR1H = 0x00; // must be clear
TMR1L = 0x00; // must be clear
ccpr1 = CCPR1H; // load higher byte register
ccpr1 = ccpr1 << 8; // shift 8 bit locations to left
ccpr1 = ccpr1 | CCPR1L; // ORs higher and lower byte to combine 16-bit
SendToUART(ccpr1);
}
}
void SendToUART(unsigned long ccpr1)
{
char buffer[16] = {‘\0’};
if (UART1_Tx_Idle() == 1)
{
//FloatToStr(freq_measured,buffer);
LongWordToStr(ccpr1,buffer);
UART1_Write_Text(“Captured Value:”);
UART1_Write_Text(buffer);
UART1_Write_Text(“\r\n”);
}
}
void CaptureModeConfig(void)
{
// CCP1M3:CCP1M0
// 0100 = Capture mode, every falling edge
// 0101 = Capture mode, every rising edge
// 0110 = Capture mode, every 4th rising edge
// 0111 = Capture mode, every 16th rising edge
CCP1CON.CCP1M3 = 0; // ———————-
CCP1CON.CCP1M2 = 1; // Capture mode, every rising edge
CCP1CON.CCP1M1 = 0; //
CCP1CON.CCP1M0 = 1; // ———————-
PIR1.CCP1IF = 0; // clear CCP Interrupt Flag bit
CCP1_dir = 1; // set input direction
CCPR1H = 0x00;
CCPR1L = 0x00;
}
void T1Config(void)
{
TMR1H = 0x00; // clear higher byte
TMR1L = 0x00; // clear lower byte
// T1CKPS1:T1CKPS0
// 11 = 1:8 prescale value
// 10 = 1:4 prescale value
// 01 = 1:2 prescale value
// 00 = 1:1 prescale value
T1CON.T1CKPS1 = 0; // 1:1 prescale value
T1CON.T1CKPS0 = 0; // 1:1 prescale value
T1CON.T1OSCEN = 1; // Oscillator is enabled
T1CON.T1SYNC = 0; // This bit is ignored
T1CON.TMR1CS = 0; // Internal clock (FOSC/4)
T1CON.TMR1ON = 1; // Enables Timer1
}

Download Files

For download “mikroC PRO for PIC” project and “Proteus 8.0” simulation files, click here.