Timer1 Interrupt of PIC16F877A Microcontroller
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In this tutorial we will learn how to how to occur Timer1 Interrupt of PIC16F877A Microcontroller. I previous tutorials we seen how to to occur Timer0 Interrupt. Here I am use Mikro C compiler for code editing. You can watch the video or read the written tutorial below.
Interrupt
Interrupt is a signal Microcontroller emitted by hardware or software indicating and event that needs immediate attention .
Timer1 Module
The Timer1 module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and TMR1L), which are readable and writable. The TMR1 Register pair(TMR1H:TMR1L) increments from 0000h to FFFFh control bit TMR1ON (T1CON<0>). and rolls over to 0000h. The TMR1 Interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit TMR1IF (PIR1<0>). This interrupt can be enabled/disabled by setting/clearing TMR1 interrupt control register. enable bit TMR1IE (PIE1<0>).
Timer1 can operate in one of two modes:
In this tutorial we will learn how to how to occur Timer1 Interrupt of PIC16F877A Microcontroller. I previous tutorials we seen how to to occur Timer0 Interrupt. Here I am use Mikro C compiler for code editing. You can watch the video or read the written tutorial below.
Interrupt
Interrupt is a signal Microcontroller emitted by hardware or software indicating and event that needs immediate attention .
Timer1 Module
The Timer1 module is a 16-bit timer/counter consisting of two 8-bit registers (TMR1H and TMR1L), which are readable and writable. The TMR1 Register pair(TMR1H:TMR1L) increments from 0000h to FFFFh control bit TMR1ON (T1CON<0>). and rolls over to 0000h. The TMR1 Interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit TMR1IF (PIR1<0>). This interrupt can be enabled/disabled by setting/clearing TMR1 interrupt control register. enable bit TMR1IE (PIE1<0>).
Timer1 can operate in one of two modes:
- As a timer
- As a counter
Timer1 Interrupt control Registers
T1CON: TIMRER1 CONTROL REGISTER
bit 7-6 Unimplemented: Read as '0'
bit 5-4 T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits
11 = 1:8 Prescale value
10 = 1:4 Prescale value
01 = 1:2 Prescale value
00 = 1:1 Prescale value
bit 3 T1OSCEN: Timer1 Oscillator Enable Control bit
1= Oscillator is enabled
0 = Oscillator is shut-off (the oscillator inverter is turned off to eliminate power drain)
bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit
When TMR1CS = 1:
1 = Do not synchronize external clock input
0 = Synchronize external clock input
When TMR1CS = 0:
This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.
bit 1 TMR1CS: Timer1 Clock Source Select bit
1 = External clock from pin RC0/T1OSO/T1CKI (on the rising edge)
0 = Internal clock (FOSC/4)
bit 0 TMR1ON: Timer1 On bit
1 = Enables Timer1
0 =Stops Timer1
PIR1 REGISTER
The PIR1 Register contain individual control bit for the peripheral interrupts.
bit 7 PSPIF(1): Parallel Slave Port Read/Write Interrupt Flag bit
1 = A read or a write operation has taken place (must be cleared in software)
0 = No read or write has occurred
bit 6 ADIF: A/D Converter Interrupt Flag bit
1 = An A/D conversion completed
0 = The A/D conversion is not complete
bit 5 RCIF: USART Receive Interrupt Flag bit
1 = The USART receive buffer is full
0 = The USART receive buffer is empty
bit 4 TXIF: USART Transmit Interrupt Flag bit
1 = The USART transmit buffer is empty
0 = The USART transmit buffer is full
bit 3 SSPIF: Synchronous Serial Port (SSP) Interrupt Flag
1 = The SSP interrupt condition has occurred, and must be cleared in software before returning from the Interrupt Service Routine. The conditions that will set this bit are:
• SPI
- A transmission/reception has taken place.
• I2C Slave
- A transmission/reception has taken place.
• I2C Master
- A transmission/reception has taken place.
- The initiated START condition was completed by the SSP module.
- The initiated STOP condition was completed by the SSP module.
- The initiated Restart condition was completed by the SSP module.
- The initiated Acknowledge condition was completed by the SSP module.
- A START condition occurred while the SSP module was idle (Multi-Master system).
- A STOP condition occurred while the SSP module was idle (Multi-Master system).
0 = No SSP interrupt condition has occurred.
bit 2 CCP1IF: CCP1 Interrupt Flag bit
Capture mode:
1 = A TMR1 register capture occurred (must be cleared in software)
0 = No TMR1 register capture occurred
Compare mode:
1 = A TMR1 register compare match occurred (must be cleared in software)
0 = No TMR1 register compare match occurred PWM mode: Unused in this mode
bit 1 TMR2IF: TMR2 to PR2 Match Interrupt Flag bit
1 = TMR2 to PR2 match occurred (must be cleared in software)
0 = No TMR2 to PR2 match occurred
bit 0 TMR1IF: TMR1 Overflow Interrupt Flag bit
1 = TMR1 register overflowed (must be cleared in software)
0 = TMR1 register did not overflow
Note 1: PSPIF is reserved on PIC16F873/876 devices; always maintain this bit clear.
Circuit diagram
Timer1 interrupt time is 250 ms. Im use here Timer Calculator for actual interrupt time.
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| Timer Calculator |
Mikro C Code:
//Timer1
//Prescaler 1:8; TMR1 Preload = 3036; Actual Interrupt Time : 250 ms
void main(){
TRISB = 0X00;
PORTB = 0X00;
T1CON = 0x31;
TMR1IF_bit = 0;
TMR1H = 0x0B;
TMR1L = 0xDC;
TMR1IE_bit = 1;
INTCON = 0xC0;
while(1){
PORTB.F1 = 1;
delay_ms(50);
PORTB.F1 = 0;
delay_ms(50);
}
}
void Interrupt(){
if (TMR1IF_bit){
TMR1H = 0x0B;
TMR1L = 0xDC;
PORTB.F0 = 1;
delay_ms(50);
PORTB.F0 = 0;
Delay_ms(50);
TMR1IF_bit = 0;
}
}
Click the download button for program file:
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| download |
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