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Payloads & Interfacing with External Boards

How to connect to external payloads, ADCS boards, etc...

Overview

Whether soldering a board onto the SMT slots or using an SMT header, the payload pinouts provide access to 3.3V, UART, I2C, SPI, and VBATT (via PYLD VDD).

Payload Headers

The inner pads of the "payload slots" can accommodate standard 0.1" surface-mount headers. 2 row, 18 pos. surface mount headers (male or female) work best.

Header soldered to mainboardv01

Example P/Ns:

  1. Amphenol 89898-309ALF
  1. Würth Elektronik 61031821821

Header Pinouts

Any of the pin names pictured above can be accessed in CircuitPython using the board object.

For example:

  • Using a pin as GPIO
    from pycubed import cubesat
import board
import digitalio

gpio = digitalio.DigitalInOut(board.PB16)
gpio.switch_to_output()
gpio.value = True  # set GPIO high
gpio.value = False # set GPIO low
  • Using I2C (SD2/SCL2)
    from pycubed import cubesat
import board
import busio

i2c2 = busio.I2C(board.SDA2,board.SCL2)
  • Using UART (TX2/RX2)
    from pycubed import cubesat
import board
import busio

uart2 = busio.UART(board.TX2,board.RX2)

# you can also swap the pins
# uart2 = busio.UART(board.RX2,board.TX2)

See 🎹Pin Muxing for more details on what pins can do what functions

Payload Board SMT Slots

Similar to the radio modules' surface mount mezzanine style, the payload board slots can accept custom PCBs soldered directly to the board. You can even span across two payload spots to accommodate larger payload designs.

Payload boards on the KickSat-2 mission
Payload board on the V-R3x mission

Full design schematics and layout for the ADC payload board pictured above:

→ Details on the Payload Board

We've even seen groups make payload boards that span both slots, like this →

Payload baord spanning both slots.
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Have you made a cool payload board? Wish the pinout was different?

Let us know on the 💬 PyCubed forums