OpenMote: Arduino-Compatible Controller for Makers

BIG announcement for openmote coming soon! PS. We're re-launching better than ever! Expect a TON more documentation and social posts about it soon!

OpenMote has been slowly improving in the background and I'm more than proud to announce that our most recent generation of designs is ready to hit the shelves! (well metaphorical shelves) complete with an micro SD card reader for those large audio files. A QWIIC connector for any additional boards that you want to add on, thanks everyone who joined us in the adafruit show and tell streams for this amazing add on.

Some Quality of life improvements we made were:

- moving the LiPo connector to be accessible from the back battery clip

- Moving the Qwiic connector to be accessible again from the back battery clip

- finally put the IR Leds on the board (control your TV with a wii remote?!)

- a bunch of other under the hood things that will make working with openmote a makers dream

enjoy this artsy picture of our hotel room for CES 2025 this year where we were hard at work writing code and testing 3d prints for OpenMote Gen3.0
 

One of the more difficult things we've had to deal with was the loss of the DAC on the ESP32-S3 framework. Without an onboard DAC we've had to get creative with driving the speaker on OpenMote. We started out with a MAX98357 a very popular I2S DAC + AMP combo IC that manages all things mono speakers. However this component was proving to be unreliable from our PCBA supplier, they were pricey and stocked in scary short numbers.

To solve this problem we dove into how to get an analog signal from the ESP without having it be an actual analog signal. This lead to the discovery of PDM and sigma delta modulation. Special shoutout to @atomic14 (Chris Greening) for his illuminating blog post about how to drive a speaker from an esp32-s3 without the need for an external DAC. 

After doing some research on amp and looking at Espressif's own documentation and guides we found an active amp that uses a TL07x. A few hours later and we've whipped up a testbed for the active amp and a microSD card slot to test all our audio needs. On this testbed we also included a 3.3V LDO to test the difference in volume from the speaker between 3.3v and 5v. Lastly we also included a little notch near the USB-C port to remove the need to clip a little piece of plastic on the old game controllers.