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How-To GPIO Header

Description

The Pi-Tron CM5 has a 40 pin GPIO header on the bottom of the PCB. This 40 pin GPIO header was originally introduced with the Raspberry Pi 2B and can still be found on the Raspberry Pi 5 today with the same pin assignments. See the how-to section below for information on the layout and a GPIO overview together with notes and usage recommendations concerning the GPIO header on the Pi-Tron CM5.

The Pi-Tron CM5 has by default only a placeholder with soldering pads for the 40 pin header, but does not come equipped with the actual header. Also this option is only available for the Board Line (BL) variant of Pi-Tron CM5. Contact our sales team for more details about this option.

pi-tron-cm4-bottom-gpio-header

Requirements

  • No Requirements

How-To

Below is a table which lists all 40 pins of the Pi-Tron CM5s GPIO header. Also see the section Restrictions below for any notes on how to operate the GPIOs and which pins have restrictions and should not be used externally.

Pi-Tron CM5 GPIO header overview:

Alternate Name Pin Pin Name Alternate
3.3V 1 2 5V
SDA1 GPIO 2 3 4 5V
SCL1 GPIO 3 5 6 GND
GPCLK0 GPIO 4 7 8 GPIO 14 UART0 TXD
GND 9 10 GPIO 15 UART0 RXD
SPI1 CS1 GPIO 17 11 12 GPIO 18 SPI1 CS0
GPIO 27 13 14 GND
GPIO 22 15 16 GPIO 23
3.3V 17 18 GPIO 24
SPI0 MOSI GPIO 10 19 20 GND
SPI0 MISO GPIO 9 21 22 GPIO 25
SPI0 CLK GPIO 11 23 24 GPIO 8 SPI0 CS0
GND 25 26 GPIO 7 SPI0 CS1
ID_SD GPIO 0 27 28 GPIO 1 ID_SC
GPIO 5 29 30 GND
GPIO 6 31 32 GPIO 12 PWM 0
PWM 1 GPIO 13 33 34 GND
SPI1 MISO GPIO 19 35 36 GPIO 16 SPI1 CS2
GPIO 26 37 38 GPIO 20 SPI1 MOSI
GND 39 40 GPIO 21 SPI1 CLK

Restrictions

  • SPI0 Chip Select 1 (Pin 26, GPIO 7) is connected to the on-board MCP251xFD CAN-Bus chip and should not be used. It is recommend to not use SPI0 at all, as external peripherals could render the CAN-Bus inoperable, however Chip Select 0 (GPIO 8, Pin 24) is unused.
  • The I²C Bus 1 has many connected devices and some bus addresses are already taken. It is recommended to check the data sheet of any new device which is to be connected to this bus that it does not have the same address as an existing device. See the how-to I²C Addresses for an overview of used addresses.