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Using 5V IR sensors with Propellor — Parallax Forums

Using 5V IR sensors with Propellor

Mike GreenMike Green Posts: 23,101
edited 2006-07-11 03:11 in Propeller 1
I just want to pass this by more experienced (probably Parallax) folks. I want to use an IR LED/Sensor pair on a single Propellor pin. These are the same IR LEDs and PNA4601M sensors that Parallax includes with the BOE-BOT kit. As far as I can tell, the sensor has an internal pullup to 5V of about 20K. This should allow the sensor to be directly connected to a Propellor pin. What I want to do is to connect the LED and its current limiting resistor between the same pin and 3.3v. This way, I can switch the Propellor pin between input and low output at about 38KHz and sample the input about mid-pulse. When the sensor sees the 38KHz signal, it holds its output low for about 400us. I should see a low at mid-pulse where I'd normally expect a high. The LED is turned on for the 400us, but this just cuts off the modulated IR. Any comments or suggestions?
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