hect0rius/allwinner-baremetal

Example baremetal programs for Allwinner H3/H2+ boards.

Allwinner H3 Bare Metal Examples

This repo contains simple, experimental code illustrating how to do a bare metal programming on Allwinner H3/H2+ boards. The code is tested on Orange Pi Zero and NanoPi Neo.

Some of the code was originally written by dwelch67. Some of the code uses an astounding H3 HAL library from Orange Pi DMX project.

Requisites

Download ARM toolchain for AArch32 bare metal from https://developer.arm.com/open-source/gnu-toolchain/gnu-a/downloads and extract it e.g. into /opt:

$ wget https://developer.arm.com/-/media/Files/downloads/gnu-a/8.2-2019.01/gcc-arm-8.2-2019.01-x86_64-arm-eabi.tar.xz
$ sudo tar -C /opt -xvf gcc-arm-8.2-2019.01-x86_64-arm-eabi.tar.xz

Download & Build

To download and build all the examples, run:

$ git clone --depth=1 https://github.com/mprymek/allwinner-baremetal
$ cd allwinner-baremetal/H3/orange-pi
$ make

Run Preparation

There are many ways how to load a built binary into the board but probably the most convenient one is to use U-Boot & TFTP.

If you are interested in this repo, you probably know how to install U-Boot into your board. The most simple way is probably to use a standard Armbian SD card and wipe out the Linux partition. If you want to dig deeper, you can read my blogpost about OrangePi netbooting or even build your own U-Boot.

You must also install a TFTP server. Consult your OS manual on how to do it.

When you have these two things prepared, edit config.mk accordingly.

I will also suppose you have DHCP working in your LAN. If it's not the case, you must configure static addresses in U-Boot which I will not describe here. Consult U-Boot documentation.

Running Manually

You can load the binary into your board using U-Boot shell. You can get into it by pressing any key on Hit any key to stop autoboot U-Boot prompt.

At first, scp the built binary to your TFTP server (replace 192.168.1.100 with your TFTP server IP address and edit the tftp directory if needed):

$ scp blinker01/allwinner-h3-blinker01.bin 192.168.1.100:/var/tftpboot/pxe/arm/

In the U-Boot shell, run:

=> dhcp
=> tftpboot 0x42000000 192.168.1.100:pxe/arm/allwinner-h3-blinker01.bin; go 0x42000000

The LED should now start to blink.

Note you must use the go command instead of boot* commands used to load the Linux kernel. This is because we load a barebone binary and we don't want U-Boot to do any magic, just jump to the given address where our binary is loaded.

Running Automatically

You can configure your board to boot the given image automatically. To gain more flexibility, we will place the U-Boot script on the TFTP server also. You will need mkimage installed on your host computer to built the script image. For Debian derivates, do:

sudo apt install u-boot-tools

At first, upload the binary to the TFTP server with:

$ make -C blinker01 install

This will copy the binary image and the boot script to your TFTP server. Then make a symlink from the particular binary's load script to the general autoboot.scr:

$ ssh root@my-tftp-server ln -s allwinner-h3-blinker01.scr /var/tftpboot/pxe/arm/autoboot.scr

By changing this symlink, you can choose which image to boot in the future.

Then you must change the command which U-Boot runs right after boot. Go to the U-Boot shell and run:

=> setenv serverip 192.168.1.100
=> setenv scriptname pxe/arm/autoboot.scr
=> setenv scriptaddr 0x43100000
=> setenv bootcmd-old "$bootcmd"
=> setenv bootcmd 'dhcp; tftp ${scriptaddr} ${scriptname}; source ${scriptaddr}'
=> saveenv; reset

This (permanently) changes U-Boot configuration to run TFTP:pxe/arm/autoboot.scr on reboot.

You can also configure the TFTP server IP using your DHCP server. In this case, omit the setenv serverip line and put the TFTP server IP into the next-server option of your DHCP configuration.