Sensors

DIP+ SIS Chapter2 - This is the notes I have for students taking the Diploma+ module in Robotics. This chapter is on IR sensors.

Line sensor

IR analog sensor

The timing diagram below shows 2 pairs of IR transmitter and receiver signals. The 2 pairs of signal are close enough so as to interfere with each other. In order to read the sensor's value correctly, the transmitters must be fired separately and receiver read separately. As shown, transmit-1 is turn ON first, for a duration >> than the rise time of the sensor. For example, the TSL262R rise time is about 7usec, hence the turn-on time I use is approximately 20usec. After the transmit-1 is ON for 20 usec, the ADC conversion for receiver-1 is started. After the conversion, the transmit-1 is turn-OFF.. As shown, when transmit-1 is ON, receiver-2 also receives some signal. transmit-1 should be turn-OFF for a duration to make sure that the signal died off before the transmit and conversion for sensor-2 is started. The cycle is then repeated.