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The SD-Dev Carrier Board

The Signaloid SD-Dev is a compact carrier board and development system for testing and characterizing the Signaloid C0-microSD. It has an open-top microSD socket so you can probe the C0-microSD debug pads, and it can measure and programmatically power-cycle the modules it hosts.

SD-Dev port diagram

Operating modes​

Peripheral mode​

Connected to a host computer over USB, the SD-Dev acts as a generic USB-to-SD adapter, exposing one microSD slot and one full-size SD slot to the host.

note

Without an on-board Raspberry Pi compute module, power the SD-Dev through the PWR+D port.

Standalone mode​

Attach a Raspberry Pi CM4 or CM5 to the carrier board to produce a compact single-board computer with hot-swappable FPGA modules. In this mode the board provides power measurement and programmatic power cycling for the on-board modules.

note

With an on-board Raspberry Pi compute module, power the SD-Dev through the PWR port so the P0 and P1 ports remain free for connecting peripherals to the compute module.

Specifications​

  • Board outline: 57 mm × 57 mm
  • 2 × USB Type-C downstream ports
  • 1 × USB Type-C upstream port
  • 1 × USB Type-C upstream power-only port
  • 1 × Micro HDMI port
  • JST connectors for SPI and I²C peripherals
  • One full-size SD slot and one microSD slot (for C0-microSD boards or regular SD cards), with:
    • SD card detection
    • programmable power cycling
    • power measurement
    • open-top microSD socket for probing the C0-microSD debug pads
  • Dual function: peripheral and standalone modes

The SD_Dev_toolkit.py and SD_Dev_power_measure.py scripts (in the Signaloid-Compute-Module-Utilities repository) drive power cycling and power measurement.

Flashing the Raspberry Pi compute module eMMC​

To flash the on-board eMMC of a compute module, follow the official Raspberry Pi documentation. The SD-Dev has no disable eMMC Boot jumper; instead, press and hold the on-board push button before connecting the SD-Dev to the host, then continue with the flashing process.

Raspberry Pi compute module as a USB gadget​

In standalone mode you can configure the attached Raspberry Pi as a USB serial or USB Ethernet gadget, so one USB-C cable gives you a console or SSH access. See the Raspberry Pi CM USB gadget guide.

Getting started​

For the full walkthrough, see the SD-Dev quickstart guide.

Next steps​

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