Smallest Form Factor Teensy 4.1

[shirogeek]

Hey guys,

I am looking into using the teensy (specifically the 4.1) ecosystem on a wearable application to achieve low latency high frequency data logging of various sensors (motion, environmental...). I was wondering if there is any open source design of "the smallest" form factor Teensy 4.1 with ideally an SD card slot (connected over SDIO). I found the micromod from sparkfun open source which can be a good starting point for a customized board...

The reason I am asking is that I have done custom ESP32 boards in the past but never a complex MCU with BGA pads even more so. Therefore, I am not particularly aware of the critical considerations for designing a board and routing signals for such a dense mcu.

Any tips or recommendations are welcome.
Thanks in advance !

[radiohound]

I think the smallest form factor for a Teensy 4.1 is a Teensy 4.0 with a SD Card connector soldered to the bottom side. The Teensy 4.0 is a very compact board. I don't see a custom board getting too much smaller. The MicroMod looks very small. But it is 22mm x 22mm, and it needs a little more room to be fitted into a connector, an SD card added, plus power regulator, usb connector, etc. the T4.0 is only 30% larger than the MicroMod, and might have almost everything you need on it.

The connector I used for the SD card is a Digikey WM14405CT-ND. It has a 1.1mm pitch instead of the Teensy's 1.0 pitch. But it works.