Having read up about pull ups and pull downs I thought it would be a good idea to use a pull down resistor with an infra red sensor that I am using on a camera trap project.
When the output from the sensor goes high as a break in the 38khz IR signal is detected pin 4 goes HIGH. This does indeed happen when there is no pull down resistor but when a pull down is used the voltage at Pin 4 reduces significantly.
With a 10k pull down resistor pin 4 goes to 0.72v
With a 56k pull down resistor pin 4 goes to 1.99v
With a 148k pull down resistor pin 4 goes to 2.58v
What am I doing wrong? Does the TSSP4038 even need a pull down reistor?
Extra info that may be useful.
I am using a LDO reglator to provide 3.3v because other components need that voltage too.
The output of the LDO seems is 2.237v rather than the expected 3.3v.
The purpose of pullup/pulldown resistors is to ensure that inputs to the Arduino are in a known state at all times and not floating at an unknown voltage, maybe HIGH, maybe LOW
I was told that I should install one by someone who knows more about electronics that me. I cant remember if it was on a forum or just someone that I met.
I dont think my mentor told me anything like that, but even so, I still dont really understand why I do not need one. Does the sensor already provide a solid “already pulled down” LOW logic signal when a suitable IR signal is present?
Anyway, no pull down needed. Great news, many thanks.
I have to go out now but any new info n this subject will be greatfuly received and studied later.
And maybe ut is a good idea to connect tge middle leg to the analog input and the 3v3 keg to 3v3 and the gnd leg to gnd... It has 3 legs for a reason...
No, you should be using a digital input. After all it has a digital output with two states, either it has received IR light or it hasn't received IR light.
