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151 lines
9.3 KiB
Markdown
151 lines
9.3 KiB
Markdown
# MangoPI MQ Pro Device Trees for Bluetooth and GPIO
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### The MQ pro is a single core allwinner D1 64bit 1Ghz, 1Gb risc-v based Pi-Zero-alike.
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This is a guide for enabling bluetooth and using the MangoPi MQ pro's IO capabilities when running Ubuntu 24.04.
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`24.04` is a LTS+ release from Ubuntu, and should provide 5+ years of updates. As such it makes a very good choice for an unattended headless device.
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## Installing Ubuntu
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There is *no* specific image provided by Ubuntu for the MQ PRO, but they *do* provide an image for the 'AllWinner Nezha' which installs and boots on the MQ Pro with almost everything working.
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Please refer to the Ubuntu documentation and forums if struggling with this.
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- I had issues getting a successful first boot with a cheap SD card, using a brand-name (Kingston) high speed card solved all the issues.
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- I am also using a high wear resistance card since I want this to run for years in a hard-to-reach location.
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### steps:
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- Download the 'AllWinner Nezha' Ubuntu image (compatible with the MQ pro) from: https://ubuntu.com/download/risc-v
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- Follow the instructions linked there to create a SD/TF card image and boot the MQ Pro using it.
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- WAIT!
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- First boot is super-slow, it may take 10+ mins before you see anything on the HDMI console.
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- If you have a USB-Serial adapter you can follow the boot via the serial console (`UART0` on the GPIO connector)
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- Eventually you can log in (`ubuntu`,`ubuntu`) and will be guided through changing password etc.
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- TODO: Wifi Setup
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- Run `apt update` then `apt upgrade` and install whatever else you need.
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The only thing **not working** out of the box is **Bluetooth**; this requires a Device Tree modification to fix. See below.
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The HDMI console with a USB kbd and mouse works well, install `gpm` to get a working mouse in it. Once i had bluetooth working I was able to attach and use a bluetooth kbd+mouse with no issues.
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#### Note:
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I experimentally installed XFCE, it took 1+ hrs to log in and get a totally unusable desktop, the GPU support is obviously not there yet. Fortunately I have no plans to use a desktop and so it got de-installed asap.
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# My Motivation:
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My MQ PRO is connected to a Waveshare LORA hat, I want to make it work but the default Nezha device tree conflicts with some of the pins my HAT uses. So I decided to 'fix' this be putting a better device tree on it.
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# Device Trees
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A device tree is a file that defines the structure of the peripherals attached to, and provided by, the GPIO and internal busses on a SBC.
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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.
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In this guide we only replace the device tree used by the kernel when Linux is started in the final stages of boot up.
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We do not need to modify the device tree used by U-Boot, or the kernel init processes, they still use the default (Nezha) device tree they were compiled against. Because this part of the boot process already works correctly we can avoid the complexity of recompiling anything.
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My pre-compiled device-trees for the MQ PRO are [here](./precompiled-trees), along with install notes.
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- I may modify this in the future as I learn how to handle kernel upgrades properly, my current install method is probably sub-optimal. But it should work.
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## Roll Your Own Device Tree
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Hopefully you can find what you want in the precompiled trees, or use the vanilla tree and dynamically create your devices on it via `pinctl`.
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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 [device-tree](./device-tree) folder.
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# Using the new tree
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## Enabling Bluetooth
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You need one of the new device trees provided here; these correctly map UART1 onto the BT controller (with RTS/CTS).
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Once that is in place you still need the correct firmware for the bluetooth adapter, a copy of this is in the [bluetooth firmware](./bt-fw) folder.
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* Copy the two firmware (`.bin`) files to `/usr/lib/firmware/` on the MQ PRO and reboot.
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## Status LED
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The onboard (blue) status LED can now be controlled via the sys tree:
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`sudo sh -c "echo 1 > /sys/devices/platform/leds/leds/blue\:status/brightness"` to turn on
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`sudo sh -c "echo 0 > /sys/devices/platform/leds/leds/blue\:status/brightness"` to turn off
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You can make it flash as wifi traffic is seen with:
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`sudo sh -c "echo phy0rx > /sys/devices/platform/leds/leds/blue\:status/trigger"`
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You can make this permanent by, as root, copying `tools/mqpro-status-led.service` to `/etc/systemd/system/`, running `systemctl daemon-reload` then `systemctl enable --now mqpro-status-led.service`.
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## Using GPIO
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Providing a full GPIO how-to is beyond the scope of this document, I use GPIOd to do this. But have also used direct pinctl control via the `/sys/class/gpio` tree.
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There are many tutorials on doing this online that give a better explanation than I can here
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## Allwinner D1 GPIO pins
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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!).
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Pins are organised into 7 'banks' (*PA*, *PB*, etc to *PG*) of up to 32 pins, but most banks have fewer pins.
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## GPIO Pin Muxing
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The **D1** SOC itself has 88 GPIO pins.
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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.
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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.
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Internally, the **D1** has a number of internal hardware interfaces for different signal types; 6xUART for serial, 2xSPI, 4xI2C(TWI), 3xI2Si/PCM (audio), 8xPWM, and some additional units for USB, HDMI, Audio, and more (see the Data sheet)
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The **D1** chip has an internal '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.
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You can browse the full range of mappings in the Allwinner D1 datasheet, Table 4-3.
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- A copy of this table is available here: [reference/d1-pins.pdf](reference/d1-pins.pdf)).
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Additionally all pins are high-impedance by default and can be set to a HIGH or LOW digital output. They can all work as digital inputs, and all have configurable pull-up and pull down resistors, and can generate interrupts. PWM and ADC input capable pins are limited, see the datasheet for more.
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### Internal interfaces
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The MQ Pro uses several of the **D1**s interfaces on-board, specifically:
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`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.
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`TWI2` (`I2C2`) can be mapped to the DVP connector (for touchscreen interfaces) via pins `PE12` and `PE13`.
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`TWI3` (`I2C3`) can be mapped to the DSI/LVDS connector via pins `PE16` and `PE17`; which also appear on the GPIO connector.
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`SPI0` is mapped to the optional SPI flash chip (not fitted on consumer units), and cannot be mapped to the GPIO connector.
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### Pin Mapping EXAMPLE
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The D1 has 6 internal UARTs, and many pin mappings are possible on the GPIO connector.
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When creating a device tree you can create any pin mapping that conforms to this:
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```text
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3v3 -- o o -- 5v
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UART1-RX PG13 ------ o o -- 5v
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UART1-TX PG12 ------ o o -- GND
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UART3-RX PB7 ------ o o ------ PB8 UART0-TX,UART1-TX
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GND -- o o ------ PB9 UART0-RX,UART1-RX
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UART1-TX PD21 ------ o o ------ PB5 UART5-RX
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UART1-RX PD22 ------ o o -- GND
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UART2-TX,UART0-TX PB0 ------ o o ------ PB1 UART0-RX,UART2-RX
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3v3 -- o o ------ PD14 UART3-CTS
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PD12 ------ o o -- GND
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UART3-RTS PD13 ------ o o ------ PC1 UART2-RX
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UART3-RX PD11 ------ o o ------ PD10 UART3-TX
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GND -- o o ------ PD15
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PE17 ------ o o ------ PE16
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UART1-RTS PB10 ------ o o -- GND
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UART1-CTS PB11 ------ o o ------ PC0 UART2-TX
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PB12 ------ o o -- GND
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UART3-TX PB6 ------ o o ------ PB2 UART4-TX
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PD17 ------ o o ------ PB3 UART4-RX
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GND -- o o ------ PB4 UART5-TX
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```
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Notes:
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- `UART0` maps by default to gpio pins 8 and 10 (*PB8* and *PB9*) is the used for the system console by default at boot and you should expect data on it during boot even if you disable it in the device tree as the kernel starts.
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- `UART1` is normally used by the bluetooth adapter, enabling it here will disable bluetooth.
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- `UART1` and `UART3` have flow control lines (rts and cts) available
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- some pins do not map to any UART devices
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## References
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There are reference copies of the MQ PRO schematic and the AllWinner D1 datasheet in the [references](./reference) folder.
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Online:
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* https://mangopi.org/mangopi_mqpro
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* https://linux-sunxi.org/MangoPi_MQ-Pro
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* https://github.com/boosterl/awesome-mango-pi-mq-pro
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