Würth Elektronik Sensor FeatherWing Kit

Würth Elektronik Sensor FeatherWing Kit

Road Test Proposal

Pressure-Based Altimeter – DougW

Background Rationale

Small integrated circuit sensors have been getting better in both performance and features, opening up more applications. It is always interesting and useful to explore the latest offerings and get a feel for their performance. Würth Elektronik has put together a FeatherWing that integrates 5 tiny sensors onto a single card, which makes it very easy to explore their performance without doing any circuit design, and indeed it allows full applications to be developed without significant design work. I find that this great suite of high performance sensors already designed into working hardware, plus a kit that includes a WiFi radio with built-in protocol stack, plus a Cortex M0 MCU, all together forms a spectacular combination for a road test and future projects. And the fact that it is free makes it irresistible.

When doing a road test I like to not only test the product performance, I also like to use the product in a real application and this kit lends itself to complete one of my bucket list project ideas. That project is a self-contained altimeter that can tell me what floor I am on based on the change in barometric pressure. The pressure sensor in this kit has a relative accuracy of 2.5 pa, and since barometric pressure changes by about 12 pa per meter, I should be able to resolve which floor I am on.

Objectives

System Development

- add a display and battery to the Feather system to allow self-contained operation

- develop firmware to read and display all sensors

Performance Characterization Test Plan

- test the accuracy of the accelerometers in measuring tilt angles - I can use a digital caliper to measure the incline triangle and calulate the angle accurately

- test the accuracy of the temperature sensor - I am not sure how accurate it is but I can test it against a thermocouple that is calibrated at freezing and boiling water temperatures

- test the humidity sensor - I can do at least a single point test with sodium chloride

- test pressure accuracy - I can do relative measurements by changing the elevation a measured distance and computing the pressure change

Application Tests

- test floor number in elevators and tall buildings

- test elevation on hills by triangulation with a laser rangefinder and the tilt angle calibrated in the performance characterization tests

Blogging

This proposal was started too close to the submission deadline to include any graphics, but the road test blog would feature images and video as well as text.

Credentials

I am an experienced electronics engineer who has successfully completed many road tests for element 14.

I have done a previous road test with Würth Elektronik - The LED Road Test+ which included 17 blogs

/products/roadtest/b/blog/posts/led-road-test---summary---blog-17-jan-15

Side Note: (not part of the application)

This proposal was written with an hour to go before the submission deadline to bolster the number of applications. Somehow this road test wasn't getting enough exposure. This application lacks graphics, detail and polish because of the last minute rush to complete it before the deadline, but hopefully it covers the basics. Meanwhile the deadline has been extended and I am publishing this to provide more exposure for the road test and in case anyone finds the content useful in their own road test applications. Feel free to use the ideas, format and content.

Road Test Page

/products/roadtest/rt/roadtests/550/wurth_sensor_feather#pifragment-4100=4&pifragment-4106=7