Detecting bed presence using thin film pressure sensors with ESPHome
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Creating a good-night-automation was one of the first things I did using Home Assistant. Although, calling it an automation isn’t quite correct as I did have to trigger it manually using the sleep tracker on my watch. Nevertheless, it is a very useful thing to have set up. Mine made sure that the cat wouldn’t trigger any of the motion sensors and would keep the bathroom lights from blinding me during nighttime visits. It would also play some white-noise on my Google Nest Mini.
The creator of today’s featured ESPHome project took things one step further and created a DIY bed presence detector using a couple of thin film pressure sensors hooked up to an ESP32. The detector even differentiates between the two halves of the bed. This sensor isn’t as uncomplicated as others that have been featured, as it makes use of the ADC sensor. But threat not, because the creator has thoroughly documented how things work.
What you need for bed presence detection
As with the PWM LED strips, this project uses an ESP32 with good reason: they have several Analog To Digital (ADC) pins. As the pressure sensor used in this ESPHome project is analogue each one needs an ADC pin to work. As soon as you want to detect more than a single person in one bed you will need multiple pressure sensors.
The easiest way of powering the ESP32 is by using the onboard USB Micro-B connector and an unused phone charger. None of the components uses enough power to warrant anything else. However, if you were to use the same ESP32 for under-bed lighting you would need a beefier power supply for the LED strips.
What makes this project interesting is the use of thin film pressure sensors. These measure the pressure between two surfaces. In this project, those surfaces are the mattress and the bed. A resistor is needed between the ground pin and the thin film pressure sensor. The creator used a 5k Ohm resistor but I guess some testing would be needed as mattresses and people don’t all weigh the same.
While the project is very well documented, the wiring, unfortunately, isn’t shown. But I did find this guide, where you will find a diagram on how to wire things up. All you have to do is replace the ESP8266 with your ESP32. Everything else should be identical. Connecting the thin film pressure sensor is slightly different compared to digital sensors, so it is handy to know how to do it correctly.
Liam Alexander Colman is an experienced Home Assistant user who has been utilizing the platform for a variety of projects over an extended period. His journey began with a Raspberry Pi, which quickly grew to three Raspberry Pis and eventually a full-fledged server. Liam's current operating system of choice is Unraid, with Home Assistant comfortably running in a Docker container.With a deep understanding of the intricacies of Home Assistant, Liam has an impressive setup, consisting of various Zigbee devices, and seamless integrations with existing products such as his Android TV box. For those interested in learning more about Liam's experience with Home Assistant, he shares his insights on how he first started using the platform and his subsequent journey.