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The imp002 is no longer available

Impee-MAX3421E is USB Host-to-Internet device built with the imp002 and the MAX3421E USB Host SoC from Maxim. It is designed to fit the Hammond 1593KBK enclosure, and design files are included in the source files below for laser-cut enclosure end plates.


The MAX3421E USB Host IC communicates with the imp over SPI. The MAX3421E supports full- and low-speed USB and internally handles low-level events like error detection and bus retries. USB client devices can be attached and removed while the device is running.

The impee-max3421E requires an external 5V power supply, and passes the supply voltage through as VBUS for attached USB clients. To prevent damage to USB client devices in the event that an incorrect power supply is used, the impee-max3421 includes over-voltage protection on VIN before passing it through as VBUS. An AP2511 USB load switch is also included, allowing the imp to detect USB client over-current events and disconnect power to USB clients.

Laser-cut Faceplates

The SVG file included in the hardware design files below can be used to purchase or create laser-cut acrylic faceplates for the Hammond 1593 enclosure. The included SVG is designed to print nine sets of faceplates in 1.5mm acrylic on the P1 (181mm x 181mm) template from Ponoko.

Note that two of the internal PCB mounting busses in the Hammond 1593 enclosure are unused in this design and will need to be removed to install the PCB.

Software Reference

Hardware Design Files

This design is can be ordered from CircuitHub.