Linux is a powerful operating system that can be compiled for a number of platforms and architectures. One of the biggest draws is its ability to be customized for an application. Tools like Buildroot, OpenWRT, and Yocto Project help us create custom Linux distributions for embedded systems.
In this video series, we will explore Buildroot and the Yocto Project. We also demonstrate how you might develop applications for embedded Linux. We will not dive into the specifics of how each of these systems work but give you a good starting place so you can read or watch more advanced material about working with embedded Linux.
See this written tutorial if you would like to review the commands issued in this tutorial for the Yocto Project: [ Ссылка ]
In the previous episode ([ Ссылка ]), we flashed our core-image-minimal image to an SD card and booted into Linux on our STM32MP157D-DK1.
In this episode, we look at enabling ports and peripherals on the microprocessor by creating a custom Linux kernel patch for the device tree. Specifically, we enable I2C port 5 on the STM32MP157D-DK1 so that we can use it to talk to a temperature sensor.
We start the process by examining the available I2C ports on the board by looking at the board’s datasheet ([ Ссылка ]). We see that I2C port 5 is available on the Raspberry Pi-style header on the board, and it is not shared with other devices. However, it is disabled by default in the core-image-minimal build.
You can find the STM32MP157 reference manual here ([ Ссылка ]), which will help you identify the starting memory address of the I2C port 5 peripheral (0x40015000).
We create a git diff patch of the original stm32mp157d-dk1.dts (device tree source) file that includes our changes. We enable the i2c5 port. We include this patch file in our custom layer (meta-custom) and create a .bbappend recipe that is added to the kernel recipe during our build process. This recipe addendum will apply the patch to the device tree source before it is built.
We also include the “i2cdetect” tool by enabling it in busybox.
We build the new kernel and device tree, flash the SD card, and boot our board. We connect the temperature sensor and probe it using i2cdetect.
Product Links:
[ Ссылка ]
[ Ссылка ]
Related Videos:
[ Ссылка ]
Related Project Links:
[ Ссылка ]
Related Articles:
[ Ссылка ]
Learn more:
Maker.io - [ Ссылка ]
Digi-Key’s Blog – TheCircuit [ Ссылка ]
Connect with Digi-Key on Facebook [ Ссылка ]
And follow us on Twitter [ Ссылка ]
