The main reason Teensy is preferred for DIY keyboards is its native USB support. Unlike most Arduino boards (like Uno, Nano, Pro Mini) that use a separate USB-to-serial chip, Teensy’s microcontrollers handle USB directly. This allows them to appear as a true USB HID device (keyboard, mouse, MIDI, etc.) without extra work. On top of that, Teensy boards generally offer more flash, RAM, and faster processors, which makes them well-suited for complex keyboard firmware like QMK or TMK that require Custom layouts, macros, and lighting effects. The Arduino Uno/Nano can’t natively emulate a keyboard without workarounds, while Teensy supports it out of the box.

I’ve seen many DIY keyboard projects where people use a Teensy microcontroller rather than popular Arduino boards like the Uno, Nano, or Pro Mini. What makes the Teensy a better choice for keyboards? Is it related to USB support, performance, or something else.

I’ve noticed that the LM317 linear voltage regulator is still widely used in various hobbyist and even some professional circuits, despite the availability of efficient and compact switching regulators. Considering that switching regulators offer better efficiency, less heat dissipation, and smaller footprints, what are the reasons engineers or designers still opt for LM317 in certain designs? Is it due to simplicity, cost, noise sensitivity, or something else?

Yes, much of the heating behaviour is inherent to older bipolar-driver ICs like the L293D and L298N. Those chips use bipolar transistors (Darlington or bipolar output stages) with large voltage drops, so a significant fraction of motor power is dissipated in the chip as heat. Wiring and supply issues (thin wires, poor decoupling, undervoltage, high stall currents) can worsen the problem, but replacing the driver with a Modern MOSFET-based H-bridge or dedicated MOSFET motor driver typically reduces losses by orders of magnitude and greatly lowers heat.

... size. The same can be said for all Arduino units. The UNO, NANO, MEGA etc are perfect as training aids and for those without the ability to produce pcbs but final products can be greatly reduced in size by using the ATMEL uController in Custom pubs. I WAs an advocate for the PIC chip series and indeed I still am but since discovering Arduino I have become a fan. As yet in Arduino I am still a beginner but I have 50 years experience in designing electronics. Cheers Jeff Monegal

I’ve been using L293D and L298N motor drivers and noticed they heat up quickly, even under light loads.Is this inherent to these older ICs, or could it be a wiring/power supply issue on my side? How much of a difference would Modern MOSFET-based drivers make in terms of efficiency and heat dissipation?

Nicely explained! Do you know if the ESP32-C3’s USB Serial/JTAG can be extended to support HID with Custom firmware, or is it strictly limited to debugging and flashing?

I need a board with native USB support for HID or Custom USB projects, and I’m trying to decide between the ESP32-C3 and ESP32-S3. Do both support native USB, and which one is more reliable for this purpose?