Part 2 of throwing Raspberry Pis at the pepper plants in my garden: On the topics of 3D printing, more bad solder jobs, I2C, SPI, Python, go, SQL, and failures in CAD

A journey through the project (by author)

In the last iteration of this project, I walked you through my journey of throwing a Raspberry Pi into my garden beds to monitor sun and water exposure. In this article, we’ll improve the prototype into something that can feasibly used both indoors and outdoors.

Just as the previous article, this here part 2 will go over all the steps I went through and documents some of the learning experiences I’ve had.

What secrets are you hiding? (by author)

Version 1 was fun — and it worked! But it wasn’t without its problems. Let’s do a quick retrospective as to what all needs to improve here.

One fairly prohibitive thing was cost — as a prototype, it used a beefy Raspberry Pi 4 (4GB), a machine that retails for a solid $55. Realistically, however, we’d want to build the same box for maybe $30 all in (at consumer prices!), so we can deploy multiple of them inside and out.

This is an easy fix — Raspberry Pi Zero W comes with WiFi (which will be cheaper and more ubiquitous than [PoE] Ethernet [0]) and can be had for $10 (if you can find one for that price). Cheap micro-SD cards retail for $3, and so do cheap micro-usb cables and power bricks, but I assume everyone has multiple piles of cables and adapters anyways. We’ll be using small breadboards, but you can also just solder copper together if you’re down for a fun ride of short circuits. Add about $2 for a solderable breadboard — and continue reading to see why that might be a good idea.

Back to the Zero W: It’s a magical little stick: 1Ghz, one core, 512MB memory, 40 PIN GPIO headers, camera connector, BLE / Bluetooth 4.1 and 802.11 b/g/n WiFi. For $10. $5 without WiFi. That’s about ~7.7x the CPU capabilities of my first PC, in about 1/1,000 the volume!

It’s fair to say that it’s tiny, about half the size of a spacebar (if that’s a unit of measurement?):

Raspberry Zero W on a Ducky Spacebar, on a bed of Cherry MX Blues (by author)

Sure — some ESP32’s might come cheaper — but Raspberries also have the distinct advantage of not being a microcontroller, but rather a fully-fledged computer. And for somebody who isn’t exactly an Embedded Engineer, the learning curve is a lot less steep. The little RasPis also support USB, which is neat!

[0] This here is a fun read that relies on PoE and…

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