write complete programs (assembly code) for the PIC16F84A to perform the following tasks using TMR0:
count the number of pulses fed into the T0CK1 pin, display the count on PORTB, and set the RA3 bit when the count reaches the decimal value of 100. the count will be continuously displayed on PORTB after setting the RA3 bit
To write a complete program in assembly code for the PIC16F84A to perform the mentioned tasks using TMR0, follow the steps below:
Step 1: Enable TMR0
- Enable the TMR0 module and configure it to increment on every rising edge of the clock signal.
- Set the prescaler to divide the input frequency by a desired value (e.g., 1:256).
Step 2: Set up I/O Ports
- Configure PORTB as an output port to display the count value.
- Configure RA3 as an output pin to set it when the count reaches 100.
Step 3: Initialize Variables
- Use a variable (e.g., "count") to store and increment the number of pulses fed into the T0CK1 pin.
- Clear the count variable to 0.
Step 4: Main Loop
- Continuously monitor the value of the count variable and update the PORTB to display the count value.
- Check if the count variable has reached 100. If it has, set the RA3 bit.
Below is an example assembly code that implements the described tasks:
```
; Define the Configuration bits for the PIC16F84A
__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _HS_OSC
; Register Definitions
COUNT equ 0x20 ; Variable to store count value
; Start of the Initialization sequence
ORG 0x00 ; Reset vector location
GOTO START
; Interrupt Service Routine
ORG 0x04
RETFIE
; Main Program
START:
; Initialize Registers
BANKSEL TRISB ; Select TRISB register
MOVLW 0x00 ; Set all PORTB pins as output
MOVWF TRISB ; Update TRISB register
BANKSEL STATUS ; Select STATUS register
BCF RP0 ; Select Bank 0
; Configure TMR0
BANKSEL OPTION_REG ; Select OPTION_REG register
MOVLW 0x07 ; Set prescaler to 1:256
MOVWF OPTION_REG ; Update OPTION_REG register
; Initialize Variables
BANKSEL COUNT ; Select COUNT variable
CLRF COUNT ; Clear COUNT variable
; Main Loop
MAIN:
BANKSEL COUNT ; Select COUNT variable
MOVF COUNT, W ; Move count value to W
BANKSEL PORTB ; Select PORTB register
MOVWF PORTB ; Update PORTB with count value
BANKSEL COUNT ; Select COUNT variable
MOVLW 0x64 ; Set 100 decimal (64 hex) value
SUBWF COUNT, W ; Compare the count value with 100
; Check if Count = 100
BZ SET_RA3_BIT ; Branch if equal (count reached 100)
GOTO MAIN ; Otherwise, continue looping
SET_RA3_BIT:
BANKSEL PORTA ; Select PORTA register
BSF PORTA, 3 ; Set RA3 bit
GOTO MAIN ; Continue looping
; End of Program
END
```
Please note that this is a basic example and might require further modifications to suit your specific requirements. Additionally, it's important to refer to the PIC16F84A datasheet and the assembler documentation for accurate and up-to-date information on registers, mnemonics, interrupts, and configuration bits.