The STM32F476 Discovery board features a STM32F7 microcontroller based on ARM® Cortex®-M7 core with 1 MB internal flash, 64 MB SDRAM, 128 MB SPI flash, a 480 x 272 TFT display, an Ethernet connector, USB host, and more. This repository contains mainly a Makefile to build a Linux system to run on this board.
The system can be loaded over TFTP via the bootloader, or it can be flashed in the internal flash. In the later case, the kernel and root filesystem with Busybox are compressed with GZIP to fit in the tight 1 MB.
Git and a compiler exported to the path are needed, such as arm-2010q1-189-arm-uclinuxeabi-i686-pc-linux-gnu.tar.bz2 from Mentor Graphics.
U-Boot from Emcraft Systems runs fine on this board and supports Ethernet, which helps a lot for development. The code comes from this repository.
Copy the U-Boot configuration into the source folder:
$ cp config/stm32f746-discovery.h src/u-boot/include/configs/stm32f746-discovery.h
Run:
$ make build_u-boot
µClinux from this repository is used and supports Ethernet, the TFT display, USART, GPIOs.
Copy the Linux configuration into the source folder:
$ cp config/linux src/linux/.config
Run:
$ make build_linux
The RAM disk is built with the files under ramdisk. This is the place to add your app. The repository contains a precompiled version of Busybox with the configuration from config/busybox_mini. To build Busybox statically and copy the executable to ramdisk/bin/busybox, run:
$ make busybox_bin
To build the RAM disk itself and wrap it in a U-Boot image, use:
$ make build/ramdisk.uImage
One scenario is to build a U-Boot image containing the kernel and the root file system, which is loaded to the board over TFTP when the bootloader starts. This is more convenient for development. Run:
$ make system_uImage
The other scenario is to build an image ready to flash containing the bootloader, the kernel and the root file system. This scenario is for embedded systems running standalone, without the need for a PC nearby. Run:
$ make system_bin
OpenOCD is used to write to the internal flash.
In order to flash only the bootloader, for example if to load the U-Boot image over TFTP, use:
$ make flash_u-boot
To flash the whole system, use:
$ make flash_system
When the internal flash contains the whole system, the Busybox prompt should come automatically about half a second after powering up the board.
When the internal flash contains only the bootloader, then a PC connected over Ethernet with the IP 172.17.0.1 must be serving the image build/system.uImage over a TFTP server.
In both cases, the U-Boot console output is sent to the USART 6 at 115200 baud.