Pro Micro RP2040 Hookup Guide
bboyho Hardware Overview
Old School to New School
The Pro Micro RP2040 design uses the original Pro Micro and Qwiic Pro Micro USB C's footprint.
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| Older Pro Micro with ATmega32U4 |
Newer Qwiic Pro Micro USB C with RP2040 |
The Pinout
All of the Pro Micro RP2040's GPIO and power pins are broken out to two, parallel headers. Some pins are for power input or output, other pins are dedicated GPIO pins. Further, the GPIO pins can have special function depending on how they are multiplexed Here's a map of which pin is where and what special hardware functions it may have.
Power
There are a variety of power and power-related nets broken out to connectors and through hole pads. Each pad has a castellated edge. The back of the board also has the USB pins broken out for power
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These nets consist of the following:
- V is the voltage provided from the USB connector.
- + is the raw, unregulated voltage input for the Pro Micro RP2040. If the board is powered via USB (i.e. V), the voltage at this pin will be about 4.8V (USB's 5V minus a Schottky diode drop). On the other hand, if the board is powered externally, through this pin, the applied voltage can be up to 5.3V.
- 3.3V is the voltage supplied to the on-board RP2040. We suggest using regulated 3.3V when connecting to this pin. If the board is powered through the raw "+" pin, this pin can be used as an output to supply 3.3V other devices.
- RST can be used to restart the Pro Micro RP2040. There is a built-in reset button to reset the board. However, the pin is broken out if you need to access this pin externally. This pin is pulled high by a 10kΩ resistor on the board, and is active-low, so it must be connected to ground to initiate a reset. The Qwiic Pro Micro will remain "off" until the reset line is pulled back to high.
- GND, of course, is the common, ground voltage (0V reference) for the system.
USB Pins
On the back of the board you can access the USB data pins and power for either USB 1.1 Host or Device.
GPIO Pins
The Pro Micro RP2040 breaks out the GPIO pins to plated through holes pads on the edge of the board. Each pad is castellated as well.
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| Top of Board with Edge PTH Pads |
Bottom of Board with Edge PTH Pads |
The Pro Micro's GPIO pins — 20 in all — (if you include the two pins on the Qwiic connector as well) are multi-talented. Every pin can be used as a digital input or output, for blinking LEDs or reading button presses. These pins are referenced via an integer value between 0 and 29.
Four pins feature analog to digital converters (ADCs) and can be used as analog inputs. These are useful for reading potentiometers or other analog devices.
All pins can be set with the pulse width modulation (PWM) functionality, which allows for a form of analog output. The RP2040 can only provide a total of up to 16 controllable PWM outputs.
There are hardware UART (serial), I2C, and SPI pins available as well. These can be used to interface with digital devices like serial LCDs, XBees, IMUs, and other serial sensors.
The RP2040 has 26 external interrupts, which allow you to instantly trigger a function when a pin goes either high, low, or changes state.
Qwiic Connector
The board includes a Qwiic connector to easily connect Qwiic enabled I2C devices to the board. SCL is connected to GPIO17 while SDA is connected to GPIO16
On-Board LEDs
There are two LEDs on the Pro Micro RP2040. The red LED indicates whether power is present. The other is the addressable WS2812 RGB LED. The addressable LED is connected to GPIO25. You'll to define functions or use the WS2812 library to control that LED.
There is a pad on the back of the board that is connected to the WS2812's DO pin. If you decide to daisy chain more LEDs, you'll want to solder to this pad.
External Flash Memory
The Pro Micro RP2040 includes a W25Q128JVPIM, which adds 128Mb (16MB) of flash memory externally.
Boot Button
The boot button is connected to the external flash memory. Pressing this button forces USB boot mode so that the board shows up as a USB mass storage device.
Reset Button
As explained earlier, there is a reset button to reset the RP2040. This adds the option of forcing the RP2040 into bootloader mode without needing to unplug/replug the board back into your USB port. To keep the board size at a minimum, the buttons are not labeled. To distinguish between the two buttons, just remember that the reset button is on the same side of the board as the reset pin.
SWD Pins
For advanced users, there are two pins (i.e. D for data/SWDIO and C for clock/SWCLK) on the back broken out for SWD programming on the back of the board. You'll need to solder wire to connect to these pins.
Board Dimensions
The board measures 1.3" x 0.7". Keep in mind that the USB-C connector is not flush with the board and will protude about 0.05" from the edge of the board. Not included in the image below is the PCB thickness, which is 0.8mm. This is thinner than a majority of PCBs used for SparkFun original designs.
