Raspberry Pi 4B

This page describes the role of the Raspberry Pi 4B in this project as well as key technical information that is relevant to developers in this project.

GPIO-Pinout-Diagram-2.png
Pin diagram from [1].

Technical Specs

An in-depth look at the technical specifications for the Pi can be found on the official Raspberry Pi website, however some key specs are listed here for convenience.

Power In

  • The Pi requires 5V +/- 0.1V (VERY precise compared to an Arduino, for example).
  • The current requirements may vary, but a safe bet is to say that the Pi requires 1A. It can take a maximum of 3A.
  • It is recommended to power the Pi using the USB-C port.
  • For the reasons listed above, I recommend using an official Raspberry Pi power supply that connects to a wall outlet.

Power Out

  • There are two voltage rails on the Pi: a 5V rail and a 3.3V rail.
  • Each GPIO pin (as well as the 3.3V rail) can only output a total current of 50mA each, with a total combined maximum of 300mA. [2]
  • The 5V rail can only supply a maximum of 1A - [total board draw]. This is because the 5V rail comes straight from the USB source, in parallel with the Pi itself. [2]

GPIO

  • There are 26 available GPIO pins to use. Care must be taken to ensure that GPIOs that have special purposes (ex: MOSI, SDA, PWM, etc.) are matched with the appropriate pins on the Pi. (See pin diagram above.)

Temperature Requirements

  • The Pi will operate normally from 0-70°C, however it is good practice to shoot for 50°C when you can. [3]

RAM and Storage Requirements

The Raspberry Pi 4B+ can be have 2GB, 4GB, and 8GB RAM. It requires a MicroSD card for storage, however there is no hard upper limit. Instead, there is a comprehensive list that demonstrates compatibility with many of the most common MicroSD card models.

All of the early development for this project was performed on a Pi with 4GB RAM and a SanDisk Edge16GB MicroSD card (provided from a Pi starter kit), and there were never any space issues.

See Also

Bibliography
1. Raspberry Pi Foundation; Raspberry Pi 4B GPIO; https://www.raspberrypi.org/documentation/usage/gpio/
2. eLinux, RPi Low-level peripherals, https://elinux.org/RPi_Low-level_peripherals#Power_pins
3. Matt Schmitt; The Operating Temperature For A Raspberry Pi; https://technologisttips.com/raspberry-pi-temperature/
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