My house has a perfectly serviceable “Lift-Master” garage door opener, installed decades before I moved in. Before, in fact, “IoT” was even a term (or practically even “I”) as its manufacturing date reads as 02/94. Nonetheless, this device’s hardwire interface–a set of dry contacts–is refreshingly easy to modernize with the addition of an IoT-controlled relay and Tasmota.

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Recently I’ve been considering how to run an LED for a really, really long time on a CR02032 battery, and eventually (re)stumbled upon the idea of a joule thief. The video below does a good job outlining how this circuit works.

In this article, I’ll first outline the basics of using MIDI with CircuitPython on the Pico for direct interface with a computer. I’ll then show how a Pi 4 (or 3/2) can be used as a host to pipe signals to a keyboard or other device.

While some microcontrollers use a tiny amount of power in shutdown mode–and even while running in some cases–e.g. the ATtiny series–others are more demanding. This can be especially true for dev boards with their additional overhead, and/or if you’re using sensors that never quite turn off power-wise.

The RP2040, with a processing speed of 133 MHz, is capable of decoding MP3 files, and the Pico RP2040 dev board includes 2 MB of Flash–enough to store a significant amount of compressed audio. At a list price of $4, the Pico therefore makes an incredible and cost-effective platform for embedded audio playback.

Depending on your level of electronics knowledge, work, and/or experimentation, a voltmeter may be sufficient for your diagnostic needs. However, being able to see the way an electronic signal changes over time, or perhaps even multiple signals, takes your analysis capabilities to a whole new level.