Access Raspberry Pi GPIO with ARM64 assembly
The Three Rs
© Lead Image © drizzd, 123RF.com
Reading, writing, and arithmetic with the Raspberry Pi in ARM64 assembly language.
In this article, I explore the Raspberry Pi's general purpose input/output (GPIO) system and look at how to use it to perform some basic input and output tasks with four separate programs that run simultaneously and communicate with each other. Table 1 lists the various programs discussed in this article [1].
Recon
The first program, gpiocount.asm, counts up or down in various number systems: binary, octal, decimal, and hexadecimal – or really, any number system up to base 16. The count mode is changed with a switch that causes an interrupt to a loadable kernel module. That's the arithmetic portion of the project.
The gpiocount program writes its values to 4 bytes of memory that is shared with gpiomux.asm, which runs in the background, reads the 4 bytes written by gpiocount, and writes the bytes into a four-digit, seven-segment display. All segment lines of the four displays are wired together inside the chip so that, to see the separate digits, you must turn on the four displays one at a time, faster than the eye can detect. That takes care of the reading, writing, and arithmetic.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
US / Canada
UK / Australia
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
openSUSE Joins End of 10
openSUSE has decided to not only join the End of 10 movement but it also will no longer support the Deepin Desktop Environment.
-
New Version of Flatpak Released
Flatpak 1.16.1 is now available as the latest, stable version with various improvements.
-
IBM Announces Powerhouse Linux Server
IBM has unleashed a seriously powerful Linux server with the LinuxONE Emperor 5.
-
Plasma Ends LTS Releases
The KDE Plasma development team is doing away with the LTS releases for a good reason.
-
Arch Linux Available for Windows Subsystem for Linux
If you've ever wanted to use a rolling release distribution with WSL, now's your chance.
-
System76 Releases COSMIC Alpha 7
With scores of bug fixes and a really cool workspaces feature, COSMIC is looking to soon migrate from alpha to beta.
-
OpenMandriva Lx 6.0 Available for Installation
The latest release of OpenMandriva has arrived with a new kernel, an updated Plasma desktop, and a server edition.
-
TrueNAS 25.04 Arrives with Thousands of Changes
One of the most popular Linux-based NAS solutions has rolled out the latest edition, based on Ubuntu 25.04.
-
Fedora 42 Available with Two New Spins
The latest release from the Fedora Project includes the usual updates, a new kernel, an official KDE Plasma spin, and a new System76 spin.
-
So Long, ArcoLinux
The ArcoLinux distribution is the latest Linux distribution to shut down.