Power

• VB (VBUS) - This is the micro-USB input voltage, connected to the micro-USB port on the Raspberry Pi Pico. It is nominally 5V.
• VS (VSYS) - This is the main system input voltage. It can range from 1.8V to 5.5V and is used to generate the 3.3V needed for the RP2040 and the GPIO pins.
• EN (3V3_EN) - This connects to the enable pin on the Raspberry Pi Pico, and is pulled high (to VSYS) via a 100kΩ resistor.
• 3V - This is the 3.3V output from the Raspberry Pi Pico.
• VR (ADC_VREF) - This is the ADC power supply and reference voltage. It is generated on the Raspberry Pi Pico by filtering the 3.3V supply. It can be used with an external reference when ADC performance is required.
• All ground pins are highlighted in white on the silk. This is the common ground for power and logic. 

I2C Logic

• SCL - I2C clock pin on the PiCowbell. It is connected to your microcontroller I2C clock line, which is GPIO5 on the Pico. This connection is shared with the STEMMA QT port on the end of the board.
• SDA - I2C data pin on the PiCowbell. It is connected to your microcontroller I2C data line, which is GPIO4 on the Pico. This connection is shared with the STEMMA QT port on the end of the board.
• STEMMA QT - These connectors allow you to connect to dev boards with STEMMA QT connectors or to other things with various associated accessories. The port is located on the end of the PiCowbell.

Duplicate GPIO Hole Pads

The following pads on the PiCowbell DVI have a duplicate hole pad next to it for solder-jumpering:

• GP0-GP13, GP18-GP22, Reset, A0-A2, VR, 3V, EN, VS and VB. Ground pins that have a duplicate hole pad are highlighted in white on the board silkscreen.
  • Note that GP3 is connected by default to the switch (Sw) on the front of the PiCowbell. It can be disconnected by cutting the Switch jumper on the back of the PiCowbell, described below.

Mini HDMI Connector

• Mini HDMI connector - On the end of the board is the mini HDMI connector. It provides DVI output to any HDMI display or monitor. The following GPIO pins are routed to the connector:
  • GPIO6: D2+
  • GPIO7: D2-
  • GPIO8: D1+
  • GPIO9: D1-
  • GPIO10: D0+
  • GPIO11: D0-
  • GPIO12: Clock +
  • GPIO13: Clock -

Additional HDMI Pins

Three additional pins for the HDMI connector are broken out in the center of the board, between the slide switch and the reset button.

• Utility pin - labeled Util on the board silk. This pin is reserved for future HDMI specification updates. It is connected to pin 17 on the mini HDMI port.
• CEC pin - labeled CEC on the board silk. Consumer Electronic Control is a one-wire bidirectional serial bus that is standardized for remote control functions. It is connected to pin 14 on the mini HDMI port.
• Hot Plug Detection pin - labeled HotPlug on the board silk. It is connected to pin 19 on the mini HDMI port. Hot plug detection is used to detect if a device is connected or disconnected to the HDMI connector by monitoring power, plug and unplug events.

Reset Button

In the center of the board, to the right of the sliding switch, is the reset button. It is routed to the reset pin on the PiCowbell and is labeled R on the board silk. You can press it to restart your program.

Slide Switch and Switch Jumper

• Slide switch - on the front of the board, to the right of the STEMMA QT port, is a slide switch that can be used for whatever purpose you like. By default it is connected to GP3, labeled Sw on the board silk.
  • It is tied to ground, reading as False in CircuitPython or LOW in Arduino, when it is switched up towards pin A2 on the silk.
  • It is open, reading as True in CircuitPython or HIGH in Arduino, when it is switched down towards pin SCL on the silk.
• Switch jumper - on the back of the board, directly next to GP3, is the Switch jumper. It is outlined in white on the silk and is labeled Switch. If you cut the jumper, it will disconnect the slide switch from GP3.