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MangoPI MQ Pro Device Trees for Bluetooth and GPIO

The MQ pro is a single core RISC-V allwinner D1 64bit 1Ghz CPU, with 1Gb RAM, HDMI and Wifi, in a Pi-Zero form factor Single Board Computer.

It runs Linux, and is quite usable as a small headless (networked, non GUI) machine.

reference/MangoPi-MQ-Pro-view.jpg

This is a guide for enabling bluetooth and using the MangoPi MQ pro's IO capabilities when running Ubuntu 24.04.1

Ubuntu Server 24.04.1 is a LTS+ release and should provide 5+ years of updates. It is a good choice for an unattended headless device.

Unfortunately there is no Official Ubuntu image for the MQ Pro, but you can use the image for the SiPeed LicheeRV. This has the same SOC as the MQ-Pro, and boots properly.

Once the LicheeRV image is booted you can swap the device tree it uses for the MQ-Pro one.

  • The correct MangoPI MQ Pro device tree is available in the firmware package, but is not the default installed by flash-kernel.
    • It is provided in the linux-modules-<kernel version> package for each kernel.
  • You can reconfigure flash-kernel to always select the MQ-Pro tree instead of the Lichee RV default in config.
    • This is future proof
    • Each new kernel release also delivers a new set of device trees that to be installed as the kernel image is created.

The idea of compiling a custom Device Tree is depreciated in favor of the vanilla MQ-Pro device tree and using gpiod and pinctl to setup devices.

  • However, I also have instructions for doing this, for those who like to tinker.

Install Steps

If you have set up SD card based systems before the following should feel familiar. You will need a SD card to boot and run the system.

  • I had issues getting a successful first boot with a generic cheap SD card, using a brand-name (Kingston) high speed card solved all the issues.
  • I am also using a high wear resistance card since I want this to run for years in a hard-to-reach location.

Notes

Unfortunately HDMI only starts very late in the boot process, you cannot use it to select GRUB options, and the console is not usable until the boot is complete.

  • Once the console login is available You can use a USB keyboard with it, and install gpm to get a working mouse.
  • Once I had bluetooth working I was able to attach and use a bluetooth kbd+mouse.

If you have a USB serial adapter available you can follow the entire boot process

  • This is the only way to access the GRUB prompt and select recovery options etc!
  • Make sure your adapter is set to 3.3v and not 5v. This is important.
  • Attach gnd, tx and rx to pins 6, 8 and 10 on the GPIO header.
  • See Jeff Geerlings excellent 'serial console uart debugging article for a good description. His example is for a Raspberry PI, but MQ Pro is identical to a Pi for this.

The WiFi module will be detected, but will not connect to any networks unless preconfigured on the SD card before first boot.

  • The instructions below show how to do this. (Requires a linux machine to mount & modify the SD card.)
  • Alternatively, wait for the console boot to finish and configure the network on that using netplan, this is also covered below.

If you have a Linux compatible USB Ethernet adapter you can attach that to the spare USB-C port on the MQ-Pro.

  • It will be detected and connected (using DHCP) during boot.
  • You will need to find the assigned IP from router logs, netscan, or looking on the console.

Creating SD card

You will need a suitable machine to download the image file to, with a SD card writer so the image can be written.

  • The instructions below are for a generic Linux system with a sd card writer.
    • As ever with this sort of operation make absolutely sure you are using the correct disk device when writing.
    • The example here assumes /dev/mmcblk0, which is the inbuilt SD card slot on my system. ymmv.
  • Windows users need to ignore the linux steps and use a tool such as Belena Etcher or similar to burn the SD card, before skipping to first boot.

Get the image file; (as of 2-Sep-2024 the url below works).

$ wget https://cdimage.ubuntu.com/releases/noble/release/ubuntu-24.04.1-preinstalled-server-riscv64+licheerv.img.xz

Unpack and copy the downloaded image to the SD card:

$ xzcat ubuntu-24.04.1-preinstalled-server-riscv64+licheerv.img.xz | sudo dd bs=8M conv=fsync status=progress of=/dev/mmcblk0

If you are going to configure Wifi/Network via the console or using a USB Ethernet adapter you can skip to First Boot below.

Preconfiguring WiFi networks

Mount the SD card you just created:

$ sudo mount /dev/mmcblk1p1 /mnt

Create a new network config file that will be applied at first init:

As root; edit /mnt/etc/cloud/cloud.cfg.d/55_net.cfg

It should have the following contents:

network:
    version: 2
    wifis:
        wlan0:
            optional: true
            access-points:
                "SSID":
                    password: "PASSWORD"
            dhcp4: true
  • Replace 'SSID' and 'PASSWORD' with your details, multiple ssid/password line pairs are allowed.
  • Be careful editing YAML files, the indentation must be exact and consistent (especially; do not mix tabs and spaces!).
  • This is for a very simple 'connect to accesspoint' scenario.
    • The Netplan syntax allows almost any possible Network setup to be preconfigured!
    • See the Netplan Documentation for lots of examples and the full syntax.
  • After first boot this file will be copied (with some comments) to /etc/netplan/50-cloud-init.yaml.
    • If you made a mistake in the config, or need to change details, edit it in /etc/netplan/ and use netplan try to test the new configuration.

Unmount the filesystem so that it is synced properly.

$ sudo umount /mnt

Eject the SD card.

First Boot

Insert the SD card into the MQ Pro and apply power.

  • First boot is SLOW. It will take 5+ minutes before anything useful appears on HDMI.
    • This is where a serial adapter is handy for following progress.
  • The HDMI console first appears after several minutes but then freezes soon after!
    • Do not panic, wait, HDMI recovers after some time as the login prompt appears.

Once the machine has booted you can login via console or SSH as ubuntu:ubuntu, and follow the mandatory instructions to change password.

WiFi config after first boot

If you are setting up WiFI after first boot you can use netplan to configure the WiFi.

Create and edit a file in the netplan config:

$ sudo vi /etc/netplan/55-wifi.yaml

The contents of this are identical to the precofigured WiFi setup given above.

  • Copy the yaml definition given there to this file and edit with your details.
  • The comments for the file there also apply here.

Apply and test your edits with:

$ netplan try

This will test your new config and reject it after a time unless you actively accept it. A very useful command.

Reconfigure to use MangoPI Device Tree

You should now have bootable machine you can access via the console or SSH. We can now reconfigure this to use the MQ Pro device tree via flash-kernel.

As root; edit /etc/flash-kernel/db

Append the following after the comments:

Machine: MangoPI MQ pro
Kernel-Flavors: any
DTB-Id: allwinner/sun20i-d1-mangopi-mq-pro.dtb
Boot-Script-Path: /boot/boot.scr
U-Boot-Script-Name: bootscr.uboot-generic
Required-Packages: u-boot-tools

This adds a new custom entry for the MQ Pro based on the default LicheeRV definition from /usr/share/flash-kernel/db/all.db, but with the correct name and device tree.

Make this the default with:

ubuntu@ubuntu:~$ sudo echo 'MangoPI MQ pro' > /etc/flash-kernel/machine

We now apply this by running flash-kernel manually.

  • flash-kernel will also be run automatically by apt and dpkg whenever kernel images are (re)installed.
ubuntu@ubuntu:~$ sudo flash-kernel
Using DTB: allwinner/sun20i-d1-mangopi-mq-pro.dtb
Installing /lib/firmware/6.8.0-41-generic/device-tree/allwinner/sun20i-d1-mangopi-mq-pro.dtb into /boot/dtbs/6.8.0-41-generic/allwinner/sun20i-d1-mangopi-mq-pro.dtb
Taking backup of sun20i-d1-mangopi-mq-pro.dtb.
Installing new sun20i-d1-mangopi-mq-pro.dtb.
System running in EFI mode, skipping.

This installs a copy of the .dtb into the /boot/dtbs/ tree and softlinks it there to be the default.

Reboot the system and you will be using the new device tree.

$ sudo reboot
# .. wait while it reboots then login again
$ cat /proc/device-tree/model

This should return MangoPi MQ Pro

First Update

$ apt update

Let this run

  • It will eventually tell you that a lot of packages need updating
$ apt upgrade

You may see packages 'deferred due to phasing', this is quite normal, an artifact of Ubuntu's build system. These can safely be ignored.

When this completes reboot again, or finish the BT setup below first since it also needs a reboot.

Setup Bluetooth adapter

Get the Bluetooth firmware files, they can be found online, but there is a copy in my repo for convenience.

$ git clone https://github.com/easytarget/MQ-Pro-IO.git

Copy Bluetooth firmware to the system firmware tree.

$ sudo cp MQ-Pro-IO/files/rtl_bt/* /usr/lib/firmware/rtl_bt/

Before you reboot to apply these you should also install bluez, which allows you to use bluetoothctl to connect and pair,etc

$ sudo apt install bluez
$ sudo reboot

Set up a service for the activity light

$ sudo cp MQ-Pro-IO/files/mqpro-status-led.service /etc/systemd/system/
$ sudo systemctl daemon-reload
$ sudo systemctl enable --now mqpro-status-led.service

The Status LED should now be continually flashing with Network activity, there is more on controlling this below.

Bask in glory!

Congratulations! 🎉

You now have a small Risc-V server that should run and be updated for several years. What you do with it is up to you!


Device Trees

In the install steps above we reconfigure the system to use the correct MangoPI MQ pro device tree instead of the Sipeed Lichee RV one.

A device tree is a file in the /boot/ area that defines the structure of the hardware provided by the chipset and SBC.

It is used in several places during initial boot to discover storage, console and other devices as needed. Once the linux kernel starts it is used to provision devices such as UART, network, gpu and other hardware. The device tree itself is a source file that is compiled into a binary to be loaded during boot.

In this guide we only replace the device tree used by the kernel when Linux is started in the final stages of boot up.

We do not need to modify the device tree used by U-Boot, or the kernel init processes, they still use the default (Sipeed Lichee RV) device tree they were compiled against. Because this part of the boot process already works correctly we can avoid the complexity of recompiling anything.

Roll Your Own Device Tree

Hopefully you can do what you need with the default tree, and dynamically create your devices on it via gpiod and pinctl.

But if not; my somewhat limited notes on compiling the tree, plus a script that handles running the C preprocessor on them (needed to get a working binary) are in the build-trees folder. There are also instructions on how to configure flash-kernel to override the upstream trees with localally built ones.

Status LED notes:

The onboard (blue) status LED can be controlled via the sys tree:

$ sudo sh -c "echo 1 > /sys/devices/platform/leds/leds/blue\:status/brightness" to turn on

$ sudo sh -c "echo 0 > /sys/devices/platform/leds/leds/blue\:status/brightness" to turn off

You can make it flash as network traffic is seen with:

$ sudo sh -c "echo phy0rx > /sys/devices/platform/leds/leds/blue\:status/trigger"

Other control options are available, $ sudo cat /sys/devices/platform/leds/leds/blue\:status/brightness shows a list and the current selection. Most do not work or are not very useful; ymmv.

My Motivation:

My MQ PRO is connected to a Waveshare LORA hat, I want to make it work but the default device tree conflicts with some of the pins my HAT uses. So I decided to 'fix' this by putting a better device tree on my board.

My Hardware

MQ Pro GPIO

Providing a full GPIO how-to is beyond the scope of this document, I use LGPIO in python to do this. But have also used direct pinctl control via the /sys/class/gpio tree.

For some basic GPIO use look at the following: https://worldbeyondlinux.be/posts/gpio-on-the-mango-pi/

Allwinner D1 GPIO pins

The D1 SOC runs at 3v3, and you must not exceed this on any of the GPIO pins. The drive current is also very limited, a maximum of 4mA on any individual pin, and 6mA total across a bank of pins (eg the 12 pins in the *PB* bank combined cannot draw more than 6mA!).

Pins are organised into 7 'banks' (PA, PB, etc to PG) of up to 32 pins, but most banks have fewer pins.

GPIO Pin Muxing

The D1 SOC itself has 88 GPIO pins.

In the MQ PRO some of these GPIO pins are wired directly to peripherals on the board (eg SD card, Wifi chip, etc.) but that still leaves many free lines.

The board has a 'standard' Raspberry Pi compatible 40 pin GPIO connector; 12 are reserved for Power lines, leaving 28 GPIO pins available for the user.

Internally, the D1 has a number of internal hardware interfaces for different signal types; 6x UART for serial, 2x SPI, 4x I2C(TWI), 3x I2S/PCM (audio), 8x PWM, and some additional units for USB, HDMI, Audio, and more (see the Data sheet).

The D1 chip uses a 'pin muxer' to connect pins to signals. Each pin can connect to a (predefined) set of signals, which allows you to map each pin on the GPIO header to multiple possible functions.

You can browse the full range of mappings in the Allwinner D1 datasheet, Table 4-3.

All pins are high-impedance digital inputs by default, they all have configurable pull-up and pull-down resistors, and can generate interrupts. Every pin can also be set to a HIGH or LOW digital output. PWM output and ADC input capable pins are limited, see the datasheet for more.

Internal interfaces

The MQ Pro uses several of the D1s interfaces on-board, specifically:

  • UART1 is used to connect to the the bluetooth device by default (with flow control) using PG6, PG7, PG8 and PG9. It can be reconfigured onto GPIO pins if bluetooth is not required.
  • TWI2 (I2C2) can be mapped to the DVP connector (for touchscreen interfaces) via pins PE12 and PE13.
  • TWI3 (I2C3) can be mapped to the DSI/LVDS connector via pins PE16 and PE17; which also appear on the GPIO connector.
  • SPI0 is mapped to the optional SPI flash chip (not fitted on consumer units), and cannot be mapped to the GPIO connector.

References

There are reference copies of the MQ PRO schematic and the AllWinner D1 datasheet in the references folder.

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