RP2040 Interfacer (UART/I2C)

The RP2040 Interfacer is a small low-cost USB to UART and I2C Adapter (both 3.3V) powered by an RP2040 microcontroller that plugs straight into a USB Type-A socket. Being powered by the RP2040 with 2MB FLASH it can be used with CircuitPython or Pico C SDK based firmware.

The serial UART connector is a 3-pin JST SH compatible socket as used on the Raspberry Pi 5 UART port.

The I2C ST/Qw connector is a 4-pin JST SH compatible with (3.3V) Qwiic/STEMMA QT. The SCL/SDA lines also have 1K resistors connected to additional GPIO lines allowing each one to have either pull up/down resistor enabled in software. The ST/Qw GPIO pins used are capable of analogue input allowing them to be used for non I2C uses, and when combined with the 1K pull resistors, can be used to measure and detect external pull up/down resistors.

On the reverse side of the connectors, there are three LEDs. In the middle is a red LED and over both UART and ST/Qw connectors are orange LEDs.

The RP2040 BOOTSEL button is dual-purpose, once the RP2040 has started up it can be used for user input.

You can also use a USB-C to USB-A adapter to allow the Interfacer to connect to many mobile phones for USB CDC Serial UART access (where supported)!

Pin Reference

The GPIO pin numbers for the connectors, LED, and button (as listed below) are also labelled on the PCB itself for quick reference

Firmware

To upload the usb_interfacer_bridge firmware to the USB Interfacer:

• Press and hold the BOOT button whilst plugging a USB cable from the device into your computer, then release the BOOT button.
• After a few seconds, an RPI-RP2 drive should appear.
• Save the latest release .uf2 file onto the RPI-RP2 drive.
• The RPI-RP2 drive will then disappear and when it connects back to the computer you should see a USB Serial and the i2c-tiny-usb port.

The board is also supported by CircuitPython the firmware can be downloaded from the CircuitPython Download page.

Package Contents

• 1x RP2040 Interfacer 

Cables not included