Koppar releases USB-C LTE modem board with voice and data
A new USB-C LTE modem board provides computers with data, SMS, and voice capabilities using a nano-SIM card.
Koppar has designed a USB-C LTE modem board that adds LTE data, SMS, and voice call functionality to a computer. The device operates using a nano-SIM card and connects via a single USB-C cable for both power and data. It receives 5 V power from the port, utilizing internal voltage regulators for the module, hub, and RP2040 microcontroller. Three LEDs on the board indicate network status in green, ringing in amber, and call activity in blue.
The board uses an RP2040 microcontroller that lacks a BOOTSEL button but supports firmware updates through specific pad group connections. The modem does not power on automatically; the microcontroller must drive the PWRKEY and RESET_N pins to activate it. VoLTE functionality is optional on the EC25-EUX module and requires specific firmware and carrier support.
The first version of the board contained errors regarding antenna impedance, buck converter placement, and SIM socket orientation. The project design files are released under the CERN Open Hardware Licence Version 2, Permissive.
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