mirror of
https://github.com/easytarget/MQ-Pro-IO.git
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94 lines
4.0 KiB
Markdown
94 lines
4.0 KiB
Markdown
# Precompiled device trees:
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Each folder contains a `.dtb` file, which is the compiled device tree itself, plus a `.dts` with the original source and a `.gpio` file showing the GPIO pin mappings.
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## Common
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[The common (generic) device tree I will use in my project, suitable for many occasions](./common)
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* Has 2x UART (plus the console uart), 2x I2C. 1xSPI
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* 12 unassigned GPIO pins
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## Serial
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[Four UART interfaces *and* Four I2C interfaces](./serial)
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* Has 4x UART (plus the console uart), 4x I2C
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* UART3 has RTC/CTS pins available too
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* 10 unassigned GPIO pins
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## SPI
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[SPI plus Serial interfaces](./spi)
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* Has 3x UART (plus the console uart), 3x I2C. 1xSPI
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* 8 unassigned GPIO pins
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## SunXI
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[Vanilla, unpopulated, upstream](./sunxi)
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* Has the console uart, nothing more
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*26 unassigned GPIO pins!*
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## AllWinner Nezha
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[DO NOT USE](./allwinner-nezha)
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* Included for completeness, this is the default device tree you get with the Ubuntu image.
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* Has the console uart, 1x I2C. 1xSPI
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* 15 unassigned GPIO pins, 3 pre-assigned to pinctl
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# Getting the DTB files
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Clone this repo:
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```console
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$ git clone https://github.com/easytarget/MQ-Pro-IO.git
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$ cd MQ-Pro-IO
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```
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# Install the Device Tree
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Installing is, in principle, simple.
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* Clone this repo on to the MQ pro and, as root, copy the desired `.dtb` file to the `/boot/dbts` folder.
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* Then make a soft link in the root of the /boot folder named `dtb-mqpro` that points to the file you just copied.
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```console
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$ sudo cp precompiled-trees/generic/6.8.0-31-generic.dtb /boot/dtbs/
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$ cd /boot
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$ sudo ln -s dtbs/6.8.0-31-generic.dtb dtb-mqpro
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```
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Finally, edit the `/boot/grub/grub.cfg` file to use the new DTB for the default 'Ubuntu' target:
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* `sudo vi /boot/grub/grub.cfg`
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* Look for the first block that begins with: `menuentry 'Ubuntu'`
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* Comment out the existing entry and add a new one:
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```console
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# devicetree /boot/dtb-6.8.0-31-generic
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devicetree /boot/dtb-mqpro
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```
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Reboot!
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After rebooting you can run **list-pins.py** (see below) to verify the new mappings.
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If you have errors rebooting (maybe a corrupt file if you rebuilt it etc..) you need to either boot using a USB serial adapter on the console pins and select the recovery image, or, in grub, edit the command and revert to the generic `/boot/dtb`.
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As a last resort you may have to remove the SD card, mount the `/boot` partition and edit `grub/grub.cfg` there.
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* !! The 'default' dtb supplied by ubuntu should always be softlinked as `/boot/dtb`, so putting `devicetree /boot/dtb` in grub in place of the custom `.dtb` should work and is predictable (no version numbers etc).
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## Examining the DTB pin mappings:
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In the [tools](../tools) folder there is a python script called `list-pins.py`.
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To run it you need to be in that directory, then run:
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`python3 list-pins.py MangoPi-MQ-Pro`
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* This produces the same map I use in the documentation and `.gpio` files in the folders above.
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* The data used to assemble the `.gpio` map files identifies which interface a pin is attached to, but not it's specific function for the interface.
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* eg it can say 'pinX and pinY are mapped to UART2', but cannot identify which pin is the TX and which is the RX; a limitation of the data, my apologies..
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* You therefore need to reference the [D1 pin mapping table](../reference/d1-pins.pdf) to get the exact functions for pins when running this for yourself.
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* The `.gpio` files uploaded here *have* been manually edited to note full pin function for convenience.
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# Making Permanent:
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(As Root) Edit: `/etc/grub.d/10_linux` line 458 to say:
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```
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for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
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```
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Note that we are adding `dtb-mqpro` to the start of this list, this is the 'search list' for the DTB files, the full section reads:
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```bash
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dtb=
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for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
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if test -e "${dirname}/${i}" ; then
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dtb="$i"
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break
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fi
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done
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```
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When Grub next rebuilds it *should* make the new DTB the default for all entries now. (this is untested, as of this writing there have not been any kernel upgrades to test them on)
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