Electronics > Electronics
help: how to eliminate sensor's noise?
black-code:
We try to make a line follower robot, but the problem of that project is the noise that comes from the sensors.
we use two line tracing sensors and they need from 12v to 30v, we applied to them 24v.
The microcontroller used is AT89C52, it needs 5v (we get this 5v from a regulator 7805) so when we common the ground of the two supplies (5v and 24v) the volt on the microcontroller becomes 7v and may reach 9v (7v is enough to make our microcontroller damaged) and that because of the noise that comes from the two sensors.
The problem happened when we common the two grounds of the two supplies so how we can solve this problem, how we can eliminate the noise to don't make the microcontroller damaged?
Any help will be appreciated, thanks in advance.
elixier:
First of all you have not mentioned what type of Sensors you have used.
Now you must separate the power supply for your logic levels which you provide for your Micro controller. Even if it sounds too funny but try it out and i think the work will be o key.
black-code:
welcome elixier .. :)
we can't separate the two supplies, we must common the two ground of the two supplies else microcontroller will not recognize on the sensors signals.
thanks for your reply
elixier:
As using a sensor the Micro controller understand only On or Off so it will work and i have tested the same.
jsmoker:
I'm not positive I understand exactly what you're saying, but as I see it you have you're unregulated 24v going into your sensor and from the 24v you regulate 5v to your micro controller, right? In this case what is the span of the output from the sensor? I'm also confused about your sensor output. I'm assuming it has an analog output, but you mentioned the microcontroller understanding only on or off so are you refering to the Vcc or the input?
Some solutions to think about:
If your output is just going out of range of the micro controller's input, consider a voltage divider. Vo = Vin*R2/(R1+R2).
If you're also looking for somekind of filter for high frequency spikes try a low pass with a resistor and capacitor. Be mindful that the resistor of the lowpass filter will also reduce your output voltage as well. Here's a calculator.
http://www.muzique.com/schem/filter.htm
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