This Feather has a lot going on! This page details all of the pin-specific information and various capabilities.

PrettyPins PDF on GitHub.

Power Pins, Connections, and Charge LED

• USB C connector - This is used for power and data. Connect to your computer via a USB C cable to update firmware and edit code.
• LiPoly Battery connector - This 2-pin JST PH connector allows you to plug in LiPoly batteries to power the Feather. The Feather is also capable of charging batteries plugged into this port via USB.
• chg LED - This small LED is located below the USB C connector. This indicates the charge status of a connected LiPoly battery when charging over USB. Note, it's normal for this LED to flicker when no battery is in place, that's the charge circuitry trying to detect whether a battery is there or not.
• GND - This is the common ground for all power and logic.
• BAT - This is the positive voltage to/from the 2-pin JST PH jack for the optional LiPoly battery.
• USB - This is the positive voltage to/from the USB C connector, if USB is connected.
• EN - This is the 3.3V regulator's enable pin. It's pulled up, so connect to ground to disable the 3.3V regulator.
• 3.3V - These pins are the output from the 3.3V regulator, they can supply 500mA peak.

Logic Pins

I2C and SPI on RP2040

The RP2040 is capable of handling I2C, SPI and UART on many pins. However, there are really only two peripherals each of I2C, SPI and UART: I2C0 and I2C1, SPI0 and SPI1, and UART0 and UART1. So while many pins are capable of I2C, SPI and UART, you can only do two at a time, and only on separate peripherals, 0 and 1. I2C, SPI and UART peripherals are included and numbered below.

PWM on RP2040

The RP2040 supports PWM on all pins. However, it is not capable of PWM on all pins at the same time. There are 8 PWM "slices", each with two outputs, A and B. Each pin on the Feather is assigned a PWM slice and output. For example, A0 is PWM5 A, which means it is first output of the fifth slice. You can have up to 18 PWM objects on this Feather. The important thing to know is that you cannot use the same slice and output more than once at the same time. So, if you have a PWM object on pin A0, you cannot also put a PWM object on D10, because they are both PWM5 A. The PWM slices and outputs are indicated below.

Analog Pins

The RP2040 has four ADCs. These pins are the only pins capable of handling analog, and they can also do digital.

• A0/GPIO26 - This pin is ADC0. It is also SPI1 SCK, I2C1 SDA and PWM5 A.
• A1/GPIO27 - This pin is ADC1. It is also SPI1 MOSI, I2C1 SCL and PWM5 B.
• A2/GPIO28 - This pin is ADC2. It is also SPI1 MISO, I2C1 SDA and PWM6 A.
• A3/GPIO29 - This pin is ADC3. It is also SPI1 CS, I2C0 SCL and PWM6 B.

Digital Pins

These are the digital I/O pins. They all have multiple capabilities.

• D24/GPIO24 - Digital I/O pin 24. It is also UART1 TX, I2C0 SDA, and PWM4 A.
• D25/GPIO25 - Digital I/O pin 25. It is also UART1 RX, I2C0 SCL, and PWM4 B.
• SCK/GPIO14 - The main SPI1 SCK. It is also I2C1 SDA, and PWM7 A.
• MO/GPIO15 - The main SPI1 MOSI. It is also I2C1 SCL, and PWM7 B.
• MI/GPIO8 - The main SPI1 MISO. It is also UART1 TX, I2C0 SDA, and PWM4 A.
• RX/GPIO1 - The main UART0 RX pin. It is also I2C0 SDA, SPI0 CS and PWM0 B.
• TX/GPIO0 - The main UART0 TX pin. It is also I2C0 SCL, SPI0 MISO and PWM0 A.
• D13/GPIO13 - Digital I/O pin 13. It is also SPI1 CS, UART0 RX, I2C0 SCL and PWM6 B.
• D12/GPIO12 - Digital I/O pin 12. It is also SPI1 MISO, UART0 TX, I2C0 SDA and PWM6 A.
• D11/GPIO11 - Digital I/O pin 11. It is also SPI1 MOSI, I2C1 SCL and PWM5 B.
• D10/GPIO10 - Digital I/O pin 10. It is also SPI1 SCK, I2C1 SDA and PWM5 A.
• D9/GPIO9 - Digital I/O pin 9. It is also SPI1 CS, UART1 RX, I2C0 SCL and PWM4 B.
• D6/GPIO6 - Digital I/O pin 6. It is also SPI0 SCK, I2C1 SDA, and PWM3 A.
• D5/GPIO5 - Digital I/O pin 5. It is also SPI0 CS, UART1 RX, I2C0 SCL, and PWM2 B.
• D4/GPIO4 - Digital I/O pin 4. It is also RX0, TX1, SDA0 and PWM2 A.
• SCL/GPIO3 - The main I2C1 clock pin. It is also SPI0 MOSI, I2C1 SCL and PWM1 B.
• SDA/GPIO2 - The main I2C1 data pin. It is also SPI0 SCK, I2C1 SDA and PWM1 A.

e-Ink Logic Pins

On the right end of the board is a 24-pin connector for plugging in an eInk display. The connector is attached to the SPI0 peripheral with six GPIO pins broken out to the connector.

• EPD_BUSY/GPIO16 - The Busy Detect pin for e-Ink displays. It is also SPI0 MISO, UART0 TX, I2C0 SDA and PWM0 A. It is available as EPD_BUSY in CircuitPython and PIN_EPD_BUSY in Arduino.
• EPD_RESET/GPIO17 - The Reset pin for e-Ink displays. It is also SPI0 CS, UART0 RX, I2C0 SCL and PWM0 B. It is available as EPD_RESET in CircuitPython and PIN_EPD_RESET in Arduino.
• EPD_DC/GPIO18 - The Data Command pin for e-Ink displays. It is also SPI0 SCK, I2C1 SDA and PWM1 A. It is available as EPD_DC in CircuitPython and PIN_EPD_DC in Arduino.
• EPD_CS/GPIO19 - The Chip Select pin for e-Ink displays. It is also SPI0 MOSI, I2C1 SCL and PWM1 B. It is available as EPD_CS in CircuitPython and PIN_EPD_CS in Arduino.
• EPD_SCK/GPIO22 - The SPI SCK pin for e-Ink displays. It is also SPI0 SCK, I2C1 SDA and PWM3 A. It is available as EPD_SCK in CircuitPython and PIN_EPD_SCK in Arduino.
• EPD_MOSI/GPIO23 - The SPI MOSI pin for e-Ink displays. It is also SPI0 MOSI, I2C1 SCL and PWM3 B. It is available as EPD_MOSI in CircuitPython and PIN_EPD_MOSI in Arduino.

CircuitPython I2C, SPI and UART

Note that in CircuitPython, there is a board object each for STEMMA QT, I2C, SPI and UART that use the connector and pins labeled on the Feather. You can use these objects to initialize these peripherals in your code.

• board.STEMMA_I2C() uses the STEMMA QT connector (in this case, SCL/SDA pins)
• board.I2C() uses SCL/SDA pins
• board.SPI() uses SCK/MO/MI pins
• board.UART() uses RX/TX pins

Arduino I2C, SPI and UART

I2C, SPI and UART can be accessed with these objects in Arduino:

• Wire is used for the default I2C and STEMMA QT connector (GPIO2 and GPIO3).
• SPI is used for the default SPI pins (GPIO14, GPIO15 and GPIO8).
• SPI1 is used for the 24-pin e-Ink connector SPI pins (GPIO22 and GPIO23).
• Serial1 is used for the default UART pins (GPIO0 and GPIO1).

The peripheral order is defined in the board support definition for Arduino. For example, you'll notice that even though the default I2C (GPIO2 and GPIO3) is located on I2C1, it is defined as Wire rather than Wire1.

GPIO Pins by Pin Functionality

Primary pins based on the silkscreen pin labels are bold.

I2C Pins

• I2C0 SCL: A3, D25, RX, D13, D9, D5, EPD_RESET
• I2C0 SDA: A2, D24, MISO, TX, D12, D4, EPD_BUSY
• I2C1 SCL: SCL, A1, MOSI, D11, EPD_CS, EPD_MOSI
• I2C1 SDA: SDA, A0, SCK, D10, D6, EPD_DC, EPD_SCK

SPI Pins

• SPI0 SCK: D6, SDA, EPD_DC, EPD_SCK
• SPI0 MOSI: SCL, EPD_CS, EPD_MOSI
• SPI0 MISO: TX, EPD_BUSY
• SPI0 CS: RX, D5, EPD_RESET
• SPI1 SCK: SCK, A0, D10
• SPI1 MOSI: MOSI, A1, D11
• SPI1 MISO: MISO, A2, D24, D12
• SPI1 CS: A3, D25, D13, D9

UART Pins

• UART0 TX: TX, A2, D12, EPD_BUSY
• UART0 RX: RX, A3, D13, D4, EPD_RESET
• UART1 TX: D24, MISO, D4
• UART1 RX: D25, D9, D5

PWM Pins

• PWM0 A: TX, EPD_BUSY
• PWM0 B: RX, EPD_RESET
• PWM1 A: SDA, EPD_DC
• PWM1 B: SCL, EPD_CS
• PWM2 A: D4
• PWM2 B: D5
• PWM3 A: D6, EPD_SCK
• PWM3 B: EPD_MOSI
• PWM4 A: D24, MISO
• PWM4 B: D25, D9
• PWM5 A: A0, D10
• PWM5 B: A1, D11
• PWM6 A: A2, D12
• PWM6 B: A3, D13
• PWM7 A: SCK
• PWM7 B: MOSI

Microcontroller and Flash

The large square towards the middle is the RP2040 microcontroller, the "brains" of this Feather board.

The square towards the top-middle is the QSPI Flash. It is connected to 6 pins that are not brought out on the GPIO pads. It is used for program and data storage in Arduino and CircuitPython.

24-Pin e-Ink Connector

On the right end of the board is a 24-pin connector for plugging in an e-Ink display. Just about every small-medium size e-Ink display made these days has a standard 24-pin connection that is compatible for plugging into this connector. The logic pins for communicating with the eInk displays are broken out and defined in both Arduino and CircuitPython.

The connector has a black bar that is pulled out to open the connection and pushed in to close the connection to secure the ribbon cable. The cable should be inserted into the connector with its pins facing up and its blue strip facing down.

You may find that you want to pair an e-Ink extension cable and FFC/FPC extender with your e-Ink display and this Feather.

Buttons and RST Pin

The Boot button is the button on the right, located on GPIO7. It is available as board.BUTTON in CircuitPython, and is available for use in Arduino as PIN_BUTTON. It is also used to enter the bootloader. To enter the bootloader, press and hold Boot and then power up the board (either by plugging it into USB or pressing Reset). The bootloader is used to install/update CircuitPython.

The Reset button is on the left. It restarts the board and helps enter the bootloader. You can click it to reset the board without unplugging the USB cable or battery.

The RST pin can be used to reset the board. Tie to ground manually to reset the board.

NeoPixel and Red LED

Above the pin labels for D24 and D25 is the status NeoPixel LED. It is connected to GPIO21. In CircuitPython, the NeoPixel is available at board.NEOPIXEL and the library for it is available in the bundle. In Arduino, it is accessible at PIN_NEOPIXEL. The NeoPixel is powered by the 3.3V power supply but that hasn't shown to make a big difference in brightness or color. In CircuitPython, the LED is used to indicate the runtime status.

Additionally, there is a NeoPixel power pin on GPIO20. It needs to be set High for the NeoPixel to be powered. This pin is available as board.NEOPIXEL_POWER in CircuitPython and NEOPIXEL_POWER in Arduino.

Above the USB C connector is the D13 LED. This little red LED is controllable in CircuitPython code using board.LED, and in Arduino as PIN_LED. 

STEMMA QT

In the middle of the board, to the left of the eInk display connector, is the STEMMA QT connector! This means you can connect up all sorts of I2C sensors and breakouts, no soldering required! This connector uses the SCL and SDA pins for I2C, which end up being the RP2040's I2C1 peripheral. In CircuitPython, you can initialize the STEMMA connector with board.STEMMA_I2C() (as well as with board.SCL board.SDA). In Arduino it is Wire.