Desk of Ladyada - Triple Matrix Bonnet & u-blox UBX Vibes

This week, we were all over the place with a bunch of different designs and experiments. After last week's analysis of the TLV320DAC3100, we made some updates to the design and re-booked prototype PCBs. We also designed a triple-matrix bonnet: with our latest work on getting HUB75 RGB matrices working on the Raspberry Pi 5, we can now do matrix control on the latest Pi 5 chip. But we're limited by the RP1 chip, so to get big displays going, we'll need multiple strands—these don't use significantly more bandwidth because half of the pins are shared. Finally, we ended the week by getting another older prototype working: the SAM-M8Q is an entry-level all-in-one GPS from u-blox. It comes with both UART and I2C interfaces, plus a built-in antenna, so it's ready to go out of the box. The NMEA interface is trivial, but we also wanted to try out the UBX interface, and thankfully, Claude 3.7 was able to vibe-code it for us in a jiffy.