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Combination SD/USB Host board for use with Teensy 4 Header Breakout board
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A combination breakout board with USB-A host and microSD connectors to mate with the Teensy 4 Header Breakout Board. Combines functionality of the USB Host Breakout and the SD Breakout.

It's designed to mount above or below the Teensy 4 and Header Breakout board on a relatively tall header.

Designed in KiCad.


  • In progress: First cut.
  • OSHPark order
  • Download bom/ibom.html and view it with web browser to see bill of materials and placement information.
  • The last pin on the right side provides an optional enable pin for the power management chip on digital pin 27. For always-on, cut left trace and short right two pads.
  • The last pin on the left side provides SD card detect on digital pin 29. Needs INPUT_PULLUP. Cut the jumper to free up pin 29.

breakout render breakout render_back schematic

Left Side Pinout:

  1. 34/SD DAT1
  2. 35/SD DAT0
  3. GND
  4. 36/SD CLK
  5. 3.3V
  6. 37/SD CMD
  7. 38/SD DAT3
  8. 39/SD DAT2
  9. 29/Card Detect

Right Side Pinout:

  1. VUSB
  2. USB Host D-
  3. USB Host D+
  4. GND
  5. GND
  6. 27/EN
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