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Title: Robot Line Sensor Question Post by: richardv2 on May 12, 2008, 10:33:31 PM I want to signal condition a phototransistor line sensor output to a digital input.
Although I am using the PIC16F8680 chip, the answer should be valid for most PIC chips. If not, please let me know. I have designed, built and tested a bank of 8 IR Transmitter/ Phototransistor pairs. They all return 1.2 to 4.2 volts at 3/8ths inch depending on a light or dark surface below the sensors. I ultimately want an 8-bit digital pattern where the sensors might react like this when travelling over a black line. 00011000 00001000 00001100 00000100 meaning the robot is drifting off center. Seems like I have several options: Lets say I use Port B as an input port. 1. If I just run the sensor inputs to the port, it would seem that I would get what I want; zeros or ones. 2. Could I send the 1.2-4.2 volt signal through some kind of chip like an inverter to "clean up" the signal and only produce 0 or 1? I know an opamp could do this, but that seems like overkill. 3. How about an LED/resistor voltage divider to drop the 1.2 down to 0.7 to make sure I get a zero into the chip at low voltage?? 4. I could use ADC, but it seems inefficient to convert the voltage into an 8 bit number just to turn it back into a one or zero. So what would you do??? |