Generated 200khz square wave with 50% duty cycle on atmega32.
Code is written in assemble language.
// Created: 9/7/2018 8:24:31 AM
// Author : abhay
.INCLUDE "M32ADEF.INC"
//.MACRO INITSTACK
LDI R16,HIGH(RAMEND)
OUT SPH,R16
LDI R16,LOW(RAMEND)
OUT SPL,R16
//.ENDMACRO
// INITSTACK
LDI R16,0X02
SBI DDRB,1
SBI DDRB,3
LDI R17,0
OUT PORTB,R17
BEGIN: RCALL DELAY
EOR R17,R16
OUT PORTB,R17
// OUT OCR0,128
RJMP BEGIN
DELAY:
LDI R22,200
OUT OCR0,R22
LDI R20,0XF2
OUT TCNT0,R20
LDI R20,0X01
OUT TCCR0,R20
AGAIN:
IN R20,TIFR
SBRS R20,TOV0
RJMP AGAIN
LDI R20,0X00
OUT TCCR0,R20
LDI R20,(1<<TOV0)
OUT TIFR,R20
RET
In this fft, it can be clearly seen that the 200khz pulse is represented by a high but we can also see the harmonic of the pulse.
Here are some more fft
