RP2040 Interfacer (UART/I2C)
Available with a lead time
Expect dispatch between Jun 26 and Jul 02
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
| GPIO | Usage |
| GP12 | UART TX |
| GP13 | UART RX |
| GP14 | UART orange LED |
| GP16 | Red status LED |
| GP17 | ST/Qw I2C orange LED |
| GP18 | 1K Resistor to SDA |
| GP19 | 1K Resistor to SCL |
| GP23 | USER Button (active LOW) |
| GP26 | ST/Qw I2C SDA/A0 |
| GP27 | ST/Qw I2C SCL/A1 |
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
Exact shipping can be calculated on the view cart page (no login required).
Products that weigh more than 0.5 KG may cost more than what's shown (for example, test equipment, machines, >500mL liquids, etc).
We deliver Australia-wide with these options (depends on the final destination - you can get a quote on the view cart page):
- $3+ for Stamped Mail (typically 10+ business days, not tracked, only available on selected small items)
- $7+ for Standard Post (typically 6+ business days, tracked)
- $11+ for Express Post (typically 2+ business days, tracked)
- Pickup - Free! Only available to customers who live in the Newcastle region (must order online and only pickup after we email to notify you the order is ready). Orders placed after 2PM may not be ready until the following business day.
Non-metro addresses in WA, NT, SA & TAS can take 2+ days in addition to the above information.
Some batteries (such as LiPo) can't be shipped by Air. During checkout, Express Post and International Methods will not be an option if you have that type of battery in your shopping cart.
International Orders - the following rates are for New Zealand and will vary for other countries:
- $12+ for Pack and Track (3+ days, tracked)
- $16+ for Express International (2-5 days, tracked)
If you order lots of gear, the postage amount will increase based on the weight of your order.
Our physical address (here's a PDF which includes other key business details):
40 Aruma Place
Cardiff
NSW, 2285
Australia
Take a look at our customer service page if you have other questions such as "do we do purchase orders" (yes!) or "are prices GST inclusive" (yes they are!). We're here to help - get in touch with us to talk shop.
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