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Processing

This service performs the following steps:

  1. For each wheel, it reads the ticks between two black stripes from the embedded RPM sensor over I2C. You can find the I2C definition and the meaning of these ticks here
  2. It converts the received data into "normal" time units (milliseconds) and extrapolates the duration of an entire rotation based on the time between two black stripes
  • Note that there are 78 black stripes mounted on the wheel, so one timer value represents 1/78th of a rotation
  1. Based on the wheel diameter, the RPM is converted to a speed in meters per second
  2. These RPM and speed values, as well as the raw ticks and sequence numbers, are encoded in the RpmSensorOutput message which is written to the rpm stream

It is highly recommended to check out the embedded RPM docs here if you want to better understand the reported values and their meaning.