Our robots use 13 ball detection modules attached to the perimeter of the robot, each of which can act as a standalone module. The design of the ball detectors is based on this document. The schematic of one such module can be found on the picture below:
The R1 and C1 are used to suppress power supply disturbances and their value is determined from the datasheet. R2 and C2 act as a low pass RC filter. This filter converts the square waves from the TSOP1138 output into an analog value. This analog output is then connected to ADC pin on an Arduino. One fully working module can be found on the picture below:
