PCB ATMEGA SMD AND LIGHT SENSOR

Hello, can I have some help, please?

I am working on the receiver part of a Visible Light Communication project. I’m using a TEMT6000 to receive the visible light, then this sensor is connected to a PCB powered by an ATmega328 SMD that will perfrom the demodulation scheme and then this PCB is serially connected to an Arduino to do another task that it is not important now.

My question is related to the PCB design. I want to make it as smaller as possible. I attached the schematics I did so far. What I’m not sure is where to connect the analog signal (SIG) from the phototransistor (The TEMT6000).

Should it be the voltage input from the voltage regulator and then the voltage output should be 5V (voltage I’m working with in the Arduino).

what about the AREF pin from the chip? maybe the SIG should also be connected there?

Thank you

Newbi

Hello there!

I did some looking and I found this article which I believe is similar to what you are doing. Give it a read to see if anything is helpful.

Here is a snippet from the article showing an example pinout.

For your question about the regulator, Since the maximum voltage you can get from the sensor is 5V, the output of the regulator would not be 5V. Regulators need an input voltage that is some amount higher than the output. This difference is called the "dropout voltage". For example, if I am using a 5V regulator with a 1V dropout voltage, the minimum input voltage I can use would 6V. In short, don't connect the sensor to the regulator.

The AREF pin is the AnalogReference voltage that the analog pins compare to, so I wouldn't connect the sensor there either.

Always, always, always add decoupling capacitors to your circuits!

See:
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Hi,
Have you bread-boarded, prototyped your project before committing to a PCB?

Did you google temt6000 arduino
and find this, with connection picture?

https://learn.sparkfun.com/tutorials/temt6000-ambient-light-sensor-hookup-guide

Is this a school/college/university project?
Can you please tell us your electronics, programming, Arduino, hardware experience?

Tom... :slight_smile: