We just received the prototypes of a new sensor board we developed for outdoor navigation. This navigation module includes a Honeywell HMC6352 compass, ST LISLV02DQ 3-axis tilt sensor, Analog Devices AD7998 8-channel A/D, and interface to GPS (we're using the Locosys LS20031). The board measures 31mm x 38mm (1.25" x 1.5"), and weighs around 5gm without GPS (18gm with GPS).

Though designed for the Surveyor SRV-1 Blackfin camera and SVS, we are using I2C interfaces to the compass, tilt sensor and A/D and UART interface to the GPS, with everything running at 3.3V, so the module is not specific to Surveyor. The 8-channel A/D enables interface to other navigations sensors such as gyros, barometric pressure, thermopiles, infrared range sensors, etc, supporting the development of a complete IMU solution. The prototype module, as seen above with the Locosys GPS, has an unfinished appearance without solder mask or silk screen, but these features will be present in the production version. We will likely ship the board without headers, but the prototype is functioning properly and is already supported in Surveyor firmware.

The schematic is found here.. Component placement is shown here:

Bottom view (no solder mask):

The navigation module is expected to be priced at $150 including Locosys LS20031 5Hz GPS, and we should have production quantities available in 30 days. If interested, please send an email to
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  • Two layer. Bottom layer has a large ground plane (no solder mask yet). Only analog component on the board is the AD7998 - everything else is relatively low-speed digital.
  • Is that a 4-layer board with hidden GND plane inside? I'm curious about the lack of copper fill in the open areas for a PCB with sensitive analog components.
  • Very interested - Please keep us informed...
  • Thank you Howard for the quick and clear answer. I moved my question to my blog not to dilute this post.
  • GPS heading is only useful if the vehicle or aircraft is moving, and in any case, it's a lagging indicator. Compass data requires smoothing, but in any case, it provides a much more current indication of actual heading than GPS.
  • A newbie question, not necessarily related to this setup: why do you need a compass module if you already have a GPS, and the program parses the GPS heading already?
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