Conducttr Blog

I’ve been having a lot of fun with the Circuit Playground Express (CPX)! It’s a £20 development platform packed with so many sensors and outputs I can hardly believe it: accelerator, temperature, light, sounds, capacitive touch….

And it’s really easy to program with Microsoft MakeCode – a scratch-like building block paradigm.

After messing around for a few days to get the hang of everything, I decided to build a simple heart rate monitor and bought an additional sensor I could strap to my finger. Ultimately I’d like to clip it to my earlobe so that I have my hands free but that’s for later.

What’s interesting and frustrating in equal measure is that the real-world throws up a lot of practical issues. For a start the heart rate sensor is an analogue device living in a digital world 🙂 So the first step was to convert the noisy signal into a more familiar digital pulse, and then there were physical issues like keeping the sensor on my finger… and then the leads came away –  hence the soldering iron!

Ultimately I got it working in a few hours and had a lot of fun experimenting with different ways to report the results.

A lot of crisis sims are designed to add some stress for the players and while galvanic skin response is supposedly the go-to technology for sensing stress, a plain heart rate is much easier to collect. Sensing the real world needs a lot of pragmatism to get it out of the lab and into the office.

While our crisis simulation software offers clients a completely closed, private environment, it is nice to be able to connect it to the real world. In the video below for example, I’m using a standard midi controller intended for music to control the Pattern of Life.

Given that the simulation can be controlled via API calls, it’s going to be fun to setup a feedback loop between my heart rate and the rate of Tweets per minute – maybe increasing the rate of tweets as the heart rate falls and reducing the rate of tweets as the heart rate increases; hence maintaining a crisis stress equilibrium! 🙂

In the meantime though I’m going to have some more fun with the CPX.


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