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
BEGIN: RCALL DELAY
// OUT OCR0,128
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.
The ds18b20 can take power in two ways. The circuit that i made is using the parasite power.
This time i used clear nail pail paint over the copper trace.
printed circuit board is designed in KiCad open source EDA tool.
UPDATE : 14 September 2018
Using nail paint as a substitute for PCB lacquer is a cheap solution. It should be avoided when making a rugged PCB. If their is a lot a mechanical vibrations and stress, then the nail paint will chip away leading to oxidation.
In my previous attempt at designing this board here. It was good. But to make the pcb smaller. I redesigned the pcb, i shifted some component here and there.
This PCB contains a 3.3v level shifter at the receiver pin.
Here are the schematics and pcb layout.
Etching time : 1 hour and 20 minutes
That’s very long time but the solution is used up. as this is a small board i don’t want to dip the board in new solution. Also i let the PCB sit for a while , and by doing this the etching is uniform and the i also found out that the traces are much sharper than before. So it is a good idea to let it sit for around 30 minutes before you shake the container. As i am doing this manually, so that is why it is a slow process.