How to reliably read sensors wirelessly in an industrial environment

Our customer in the automotive industry has a cabled measurement system to readout specific sensors. Connecting and disconnecting the cables is cumbersome. We are asked to build a wireless solution.

The system requirements are:

  • battery-powered portable sensor unit. Multiple units communicate to a shared base station.
  • high-resolution ADCs
  • wireless sensor readings are sent over a ZigBee wireless link (2.4 GHz)
  • seamless wireless network configuration
  • auto channel selection (avoids WiFi, Bluetooth, Zigbee, … interference)
  • power optimized design, both in hardware and firmware
  • OLED display for excellent readability in all lighting conditions
  • the customer wants to be able to make firmware modifications

We built the system on a multi-layer PCB within the constraints of the housing the customer designed. The system is built around an NXP LPC1768 ARM Cortex M3 processor. We implemented a bootloader over USB that enabled easy firmware upgrades in the field, and built the application firmware around the mbed toolfow, enabling the customer to easily make firmware changes once we delivered the design.