HA Flexispot Standing Desk

This is an integration of a standing desk from Flexispot into home assistant in micropython. The height can be read out from the desk's controller and it gets pushed to Home Assistant via MQTT. I guess it should be quite simple to adapt this to any other (smarthome) system. I've also implemented remote controlling the desk via MQTT (see Control section).

The desk controller has two RJ45 ports, one is used by the default remote of the table and the other one is unused. Both can be used to control the desk.

Usage and installation

I took an ESP32 and an old ethernet cable, cut it and soldered dupont wires with a female end to the Pins 4, 5, 6, 7 and 8. On the pin assignment table below you can have a look which ports to use on the ESP32.

Installation of Micropython on ESP32 is explained on this site: http://docs.micropython.org/en/latest/esp32/tutorial/intro.html#esp32-intro

For uploading the files I used ampy.

Control

If you want to control your desk remotely, make sure to call the function listen_mqtt() after initializing the Flexispot Class:

# main.py
import machine
import flexispot

def main():
    f = flexispot.ControlPanel(publish_discovery=False, debug=True)
    f.listen_mqtt()
       
if __name__ == '__main__':
    main()

The possible commands are just like the buttons on your normal external control panel:

up
down
pos1
pos2
pos3
m

Send the command as plain text like pos1 via MQTT to the command topic (default: homeassistant/sensor/standingdesk/set).

Home Assistant configuration.xaml

These are my custom sensors I've added to my configuration.yaml:

# configuration.xaml
mqtt:
    broker: <MQTT Broker>
    discovery: true

binary_sensor:
  - platform: template
    sensors:
      standing_at_desk:
        friendly_name: "Standing at desk"
        value_template: >-
            {{states('sensor.standingdesk')|float > 100}}

sensor:
  - platform: history_stats
    sensors:
      standing_today:
        name: Standing today
        entity_id: binary_sensor.standing_at_desk
        state: "on"
        type: time
        start: '{{ now().replace(hour=0, minute=0, second=0) }}'
        end: '{{ now() }}'

The binary sensor standing_at_desk switches to on if the reported height of the desk is higher than 100cm. This is the indicator that I'm standing right now. The sensor standing_today counts how long I was standing for today.

PIN Assignment

Thanks to stan from this topic.

PIN	Color	Description	Port on ESP32
1	brown	Reset of µC
2	white	SWIN of µC
3	purple	unused
4	red	needs to be set to HIGH if you want to talk to the controller	D18
5	green	RX (of remote)	RX2
6	black	TX (of remote)	TX2
7	blue	GND	GND
8	yellow	VDD (5V)	VIN

Protocol

Again thanks stan and minifloat from this topic.

Each message starts with 0x9b and ends with 0x9d. The second byte is the message's length and the third one is the message identifier. The last two bytes before message end 0x9d is a 16bit Modbus-CRC16 Checksum.

0	1	2	3	4	5	6	7	Direction	Command
9b	06	02	00	00	6c	a1		Tx	no button pressed
9b	06	02	01	00	fc	a0		Tx	up
9b	06	02	02	00	0c	a0		Tx	down
9b	06	02	04	00	ac	a3		Tx	Pos. 1
9b	06	02	08	00	ac	a6		Tx	Pos. 2
9b	06	02	10	00	ac	ac		Tx	Pos. 3
9b	06	02	20	00	ac	b8		Tx	M
9b	07	12	xx	xx	yy	yy	9b	Rx	Height
tbc

Height

If you want to query the height you have to send the "no button pressed"-command first. After that the controller will transmit the encoded height.

Message Identifier for the height reported by the controller is 0x12 with three bytes of payload. Every byte represents a digit on the display, every bit of each byte represents one segment of a seven segments display. See method decode_digit(b) or following image:

  0 0 0
5       1
5       1
5       1
  6 6 6
4       2
4       2
4       2
  3 3 3    77