E-Paper Display 24-pin Connector

• 24-pin Connect - This connector allows you to connect bare E-Paper displays.

Pins needed for using the display:

• MOSI/MISO/SCK - SPI pins are connected to the default SPI port on the Raspberry Pi.
• CS on Raspberry Pi CE 0.
• DC on Raspberry Pi GPIO 22.
• Reset on Raspberry Pi GPIO 27.
• Busy on Raspberry Pi GPIO 17

RESE Resistor Switch

In the center of the Bonnet is a slide switch with 3Ω and 0.5Ω labels on the board silk. This switch changes the resistor value for the RESE pin for the E-Paper display. 0.5Ω is the most common value, but check your display datasheet to confirm.

Buttons

There are two buttons on the right side of the Bonnet, connected to GPIO 5 and GPIO 6. You can use these as inputs.

STEMMA QT Connector

• STEMMA QT - This connector, on the left side of the Bonnet, allows you to connect to sensors and breakout boards with STEMMA QT / Qwiic connectors or to other things with various associated accessories.
• SDA/SCL - The I2C pins for the STEMMA QT connector are connected to the default I2C port on the Pi.
• 3.3V/GND - The power for the STEMMA QT connector is 3.3V. Ground is the common ground for power and logic.

STEMMA JST PH

• STEMMA JST PH - towards the right side of the Bonnet is a 2mm pitch STEMMA JST port for use with 3-pin STEMMA JST PH cables. It has connections for:
  • GND - common ground for power and data. It is the black wire on the JST PH cable.
  • +5V - connected to 5V power on the Raspberry Pi. It is the red wire on the JST PH cable.
  • #12 - connected to GPIO 12 on the Raspberry Pi. It is the white wire on the JST PH cable.

I2S Amplifier, Speaker Output and Gain

The Bonnet uses the MAX98357 I2S amplifier chip for digital audio. It uses the following pins:

• BCLK - GPIO 18
• LRCLK - GPIO 19
• DIN - GPIO 21

Towards the center of the Bonnet is the speaker output terminal block. It can drive a 4-8Ω speaker.

Directly above the MAX98357 is the Gain jumper. By default, the gain is set to 6dB. If you cut the jumper, it will set the gain to 9dB.