Automatic standing desk control over GPIO.
The software is built around an aiohttp server. It runs on a device with GPIO pins which it uses to control controls the desk and it maintains the current state (and history) in a SQLite database. The server also maintains a timer which fires when its time to change position.
The client observes the lock/unlock events of the used computer as an activity indicator and passes these events on to the server. The server then uses them to calculate when to raise or lower the desk.
The GPIO pins are wired up to control two electrical switches (relays, transistors, opto-couplers or something with similar function). These electrical switches are connected to the ports of the up/down buttons on the desk's control dongle. If your desk use a more complicated control protocol, you have to use a different approach.
Several desks with different connectors have been tested.
The TiMOTION TC11 desk controller uses the following wiring with a 10P10C connector. Wiring of the included two-button controller as follows (counting as in the TIA-568 table on Wikipedia, not including the two unused pins at either end of the connector):
| Pin | Desk connector | T568B color | Voltage | Function |
|---|---|---|---|---|
| 1 | not connected | |||
| 2 | not connected | |||
| 3 | not connected | |||
| 4 | white | blue | +5V | down |
| 5 | black | white/blue | +5V | up |
| 6 | brown | green | 0V | common |
| 7 | not connected | |||
| 8 | not connected |
Bridging down/up to common moves the desk accordingly.
The tested desk (whose brand has since been forgotten) used the following wiring with a 8P8C connector, colors being from the T568A standard:
blue <-> blue/white => up
blue <-> brown => down
The tested desk (whose brand has since been forgotten) used the following wiring for 7-pin DIN connector:
1 <-> 2 => up
1 <-> 3 => down
(numbering clockwise male connector):
4
3 5
2 6
1 7
Below is an example schematic connecting the digital GPIO pins of a FT232H (can
also use a Raspberry Pi) with the desk controller using two 4N35
optocouplers. Additionally, the following features are included:
- LED to indicate that the desk is moving,
- LED to indicate the session state,
- override buttons for manually adjusting desk height,
- additional input button for software features.
A PCB have been designed for the schematic above:
Schematic and PCB design created with EasyEDA and available here: easyeda.com/daoo/autodesk.
There is two parts to get this running, client and server.
The server runs on a raspberry or directly on the same PC as the client if you have for example a Adafruit FT232H. In general it needs to be a computer with access to GPIO pins.
A HTTP API for manually controlling the desk, setting the session state and also showing some nice statistics. The client must be able to reach this API over HTTP for the entire system to function. If running the server on a raspberry Pi it is recommended to use SSH for security.
The client can be any computer that can make HTTP requests to set the session state on the server. The tricky part is hooking in to the lock/unlock events. On Linux a pydbus is used to listen to the session activation events. On Windows the task scheduler can be set up to run specific scripts on session activation events.
The program can be setup on a Windows or a Linux computer using the following instructions.
Make sure libusb is installed using the system package manager. For example,
on Arch Linux:
# pacman -S libusb
Use the following commands to setup the server:
$ cd ~/opt
$ git clone https://github.com/daoo/autodesk
$ cd autodesk
$ python -m venv ./.venv
$ ./.venv/bin/python -m pip install --upgrade pip setuptools
$ ./.venv/bin/pip install .
Now the autodesk server can be started in the the shell:
$ ./bin/start-autodesk.sh
On Linux, run the logger.py script to listen for lock/unlock events via DBus.
Supply it with the URL to the session API endpoint like this (autodesk is the
host name of the computer running the server):
$ logger.py http://autodesk/api/session
The host name could be localhost if using the previously mentioned FT232H.
Before running the autodesk server the USB driver needs to be configured.
Download Zadig and use it to change the driver to
libusbK for the FT232H device. See Adafruit's
guide
for more information.
Use the following commands to setup the server:
$ cd ~/opt
$ git clone https://github.com/daoo/autodesk
$ cd autodesk
$ python -m venv ./.venv
$ ./.venv/Scripts/python -m pip install --upgrade pip setuptools
$ ./.venv/Scripts/pip install .
Now the autodesk server can be started in the shell:
$ ./bin/start-autodesk.ps1
Use the Windows task scheduler to setup tasks that sets the session state using
the bin/autodesk-activate.ps1 and bin/autodesk-deactivate.ps1 scripts.