Curriedbuffalo's Remote Sensor pHAT Turns a Raspberry Pi Zero Into an IoT Remote Monitoring Station

Add-on board includes PicoBlade connectors for external sensor boards, four analog inputs, GPIO, and even a software-controlled fan.

Pseudonymous hardware designer curriedbuffalo is seeking feedback on an add-on board for the Raspberry Pi Zero family of single-board computers, designed to make them better suited to remote monitoring projects: the Remote Sensor PHAT Mk4.

"I've been using Pi Zeroes to build remote monitoring stations for some beehives," curriedbuffalo explains. "I'm on my 4th iteration, hence MK4. First version was just breakouts wired together. MK2 attempted to package these into a much smaller 3D printed case, but was too fiddly and prompted me to learn about circuit board design. MK3 was basically just a soldering aid circuit board for connecting all the breakouts sensibly in a small space. MK4 incorporates the breakout circuits and some additional features most notably the fan."

In its fourth incarnation, the board includes a small 5V fan with software control for cooling, an ADS1015 analog-to-digital converter (ADC) with four 5V analog inputs, breaks out 3V3 I2C, 5V sensor inputs, serial receive and transmit, and spare general-purpose input/output (GPIO) pins, plus Molex PicoBlade connectors for add-on boards offering an HX711 digital scale circuit, an I2S microphone, and additional GPIO.

"The beehive monitors have full HD video of the entrance, stereo audio from inside the hive, as well as internal temperature and humidity and external lux level and weight," curriedbuffalo notes. "Unfortunately, even in UK weather, streaming 1080p at 30fps over Wi-Fi seems to cause a Pi Zero to reach it's thermal limits and shut down. So I designed MK4 to include a fan for the GPU."

"The only other thing I would have liked to fit on the board was a wide input / battery input power supply circuit to automatically accept 3-12v so I could run the monitoring stations directly off solar or LiPo batteries, but I couldn't make that fit (I just use 12v car USB adaptors for power). Or alternatively a PoE circuit."

Curriedbuffalo is seeking input on the design over on Reddit, in the hopes the project may prove useful for others seeking to put Raspberry Pi Zero boards into use as remote monitoring stations.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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