100KHz Square Wave generator using PIC16C84

Following on from the LED flasher circuit, we can reduce the delay in the loop to 10uS (10 microseconds) and produce a 100Khz square wave.

100KHz Square Wave

Given a 4 Mhz PIC 16C84, the program below will generate a 100Khz square wave on PORTA bit 0 (i.e. pin 17). This little program is useful for testing oscilloscopes (though it is not very accurate).

This program is available as:

; Mark Crosbie  9/12/98
; Scope test program. Generate a 100Khz square wave.
;  The Program simply sets up Bit 0 of Port "A" to Output and then
;  loops, setting the value alternatively low and high
;  Hardware Notes:
;   Reset is tied through a 4.7K Resistor to Vcc and PWRT is Enabled
;   A 220 Ohm Resistor and LED is attached to PORTA.0 and Vcc
;	device	pic16c84
include "p16c84.h"
;  Mainline of FlashFast
org 0
clrf   PORTA                  ;  Clear all the Bits in Port "a"
clrf   STATUS
bsf    STATUS, RP0            ;  Goto Bank 1 to set Port Direction
bcf    TRISA, 0               ;  Set RA0 to Output
bcf    STATUS, RP0            ;  Go back to Bank 0
movlw 1                       ;  Turn on the LED on Port A
movwf PORTA                   ;
movlw 5
call mdelay			; 5 uS delay
movlw 0                       ;  Turn off the LED on Port A
movwf PORTA                   ;
movlw 5
call mdelay			; 5uS delay 
goto Loop
; counter variables

For more detail: 100KHz Square Wave generator using PIC16C84

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