2.2. Bike Frame Module

This module is used to determine the speed, cadence and rider’s power during the ride activity. All this data is serialized and sent via USB to the Raspberry Pi, which acts as a master of the entire system, but also as an internet gateway. Being also a standalone module, it is powered by a rechargeable battery. The wiring diagram is presented in Figure 4.

Bike frame module wiring diagram.

For data processing, an Arduino Mega 2560 was used, which communicates with the Raspberry Pi via USB. The 16 MHz processing frequency of the microcontroller allows implementation of multiple tasks in a Real Time Operating System (RTOS). The necessity of using an RTOS occurred from the need to read and compute sensor values with higher precision and data transmission.

To monitor the rider’s position continuously, a GPS module from Adafruit was used. This device has a sensitivity of −165 dB, 10 readings per second, 66 channels, and the possibility to receive signals from 22 satellites with its own integrated antenna. The latitude and longitude are sent via a FTDI USB-TTL converter to the Raspberry Pi.