ESPHome Nest thermostat clone on cheap rotary display

veli · April 22, 2023, 4:22pm

I bought a rotary display on aliexpress, was pretty disappointed to find it did not have touch, the display was not full size, etc.

So it was in the electronics pile for a while, until I came up with the best I could with the awkward rectangular display inside a circular form factor.

Currently it’s not connected to a physical thermostat outlet, but a virtual HA device to get the sensor values.

Fun features

Show a QR code if it’s not connected to wifi
1.1 Show another QR code to add it to HA if not connected to API
Climate state, temperature, current_temperature, etc
Icons, mapped to preset_mode and state
Colored background like Nest if heating, text ECO if in eco preset_mode

Actual device

Now I’m less disappointed and think it can be usable. The rotary sensors are a little off, the pushbutton doesn’t work reliably, but it has a vibration motor inside which is fun.

It was to find out what pin does what from this schematic, maybe haven’t figured it all out yet.

Will post ESPHome code soon, have some bugs to iron out.

Future:

Can be skinned pretty easily, so one can choose Nest or Apple Home styles:

stevemann · April 23, 2023, 2:57am

Bummer- I am looking for exactly that display, but Ali Express responds with: “Sorry, this item is no longer available!”

RoadkillUK · April 23, 2023, 1:20pm

Try this

veli · April 23, 2023, 3:14pm

If i was buying a new one and knew what I know now, I’d get a full width display and not a esp32 solo chip, so, either one:

veli · April 23, 2023, 7:11pm

More theme possibilities:

Apple (Home app)
Nest
Google Home (app)

nickrout · April 23, 2023, 9:15pm

Looking forward to your code

stevemann · April 23, 2023, 11:55pm

Thanks. One is on order.

stevemann · May 6, 2023, 11:14pm

OK, got it in the mail today. I would have appreciated it if AliExpress ever included any data sheets or user instructions.

Can you please share your code so far, and how to flash the knob?

nickrout · May 6, 2023, 11:24pm

There is a schematic above. Which one exactly did you buy?

stevemann · May 6, 2023, 11:47pm

The first one on the page suggested by @RoadkillUK RoadkillUK
The schematic is the main board, not the interface board. I am looking forward to seeing the YAML code and tips for how to flash the unit.

nickrout · May 7, 2023, 2:15am

I assume this one then, which actually has two models, which one did you get?

https://www.aliexpress.com/item/1005003875842752.html

stevemann · May 7, 2023, 3:06am

That is what I ordered, but this is what I received:

whatigot

nickrout · May 7, 2023, 3:10am

Interesting! That back piece doesn’t seem to be pictured on the advert! Does it come off easily? I can’t find the similar thing I bought a year or more ago! (Never got it going, it is (somewhere) in the to do pile.

stevemann · May 7, 2023, 3:43am

It plugs into the back. I haven’t opened it up yet.

nickrout · May 7, 2023, 3:48am

That looks like the connector on the back of mine.

From the advert on ali, it appears to be this:

I assume the smaller white connector plugs into the mainboard and the black connector is what you see on the back of the device. This may enable you to trace what is connected to where on that green sub-board.

What happens when you plug the USB into a computer with a data cable? Is it showing as a serial device? Or perhaps the USB only supplies power.

stevemann · May 7, 2023, 3:55am

Just power. And a demo program in Chinese.

nickrout · May 7, 2023, 3:57am

So are Rx and Tx connected to the USB port? (Assuming you have a meter to check )

stevemann · May 7, 2023, 4:19am

There are few traces going to the USB-C connector, and those two vias in the center go to the USB jumpers JP1 and JP2, bot open.

I haven’t opened it to see where the many-pin connector goes.

There is also a short ‘debug’ cable and board:

So it looks like flashing the module should be straightforward. Now I just need the code…

veli · May 7, 2023, 9:06am

I didn’t get the debug cable - just open the screws on the circle and you find TX RX IO0 and GND pins exposed.

here’s what i found:

esp32:
  board: esp32-s2-saola-1
  framework:
    type: arduino
    version: 2.0.3
    platform_version: 5.0.0

output:
  - platform: ledc
    id: ${device_name}_backlight_pwm
    pin: GPIO35
    frequency: 19531Hz
    zero_means_zero: true

spi:
  clk_pin: GPIO14 # sck : 14
  mosi_pin: GPIO33 # sda : 33

display: # 240 x 320
  - platform: st7789v
    id: ${device_name}_display
    model: Custom
    width: 240
    height: 320
    offset_height: 0
    offset_width: 0
###
    eightbitcolor: true # OR IT BREAKS
###    backlight_pin: GPIO35 ## breaks color
    update_interval: 20s
    cs_pin: GPIO34
    dc_pin: GPIO13
    reset_pin: GPIO21

switch: 
  - platform: gpio
    pin: 
      number: 18
    name: Motor
    id: ${device_name}_motor
    entity_category: diagnostic
    icon: mdi:vibrate
    on_turn_on:
      then:
        - delay: 0.1s
        - switch.turn_off: ${device_name}_motor
    internal: true

light:
  - platform: monochromatic
    id: ${device_name}_backlight
    output: ${device_name}_backlight_pwm
    icon: mdi:brightness-percent
    name: Backlight
    default_transition_length: 500ms
    restore_mode: ALWAYS_ON

binary_sensor: 
## will not work as rotary_encoder sensor because it bounces all over...
  - platform: gpio
    pin: 
      number: GPIO17 
    name: TEST left # is okay
    id: ${device_name}_gpio17_debounced

  - platform: gpio
    pin: 
      number: GPIO16
    name: TEST right
    id: ${device_name}_gpio16_debounced
    filters:
      - delayed_on: 200ms
      - delayed_off: 500ms
      - lambda: |-
          if (id(${device_name}_gpio17_debounced).state) {
            return x;
          } else {
            return {};
          }
    on_state:
      then:
        - lambda: |-
            if (id(${device_name}_gpio17_debounced).state) {
              id(increment_number).execute();
            } else {
              id(decrement_number).execute();
            }
        - script.execute: vibrate

## tried all delays, still cant get it to work reliably 
  - platform: gpio
    pin: 
      number: GPIO2
    name: Button
    id: ${device_name}_button
    icon: mdi:circle-outline
    filters:
      - delayed_on: 100ms 
      - delayed_off: 100ms 
      - delayed_on_off: 550ms 
    on_press:
      - lambda: |-      
          ESP_LOGW("button", "pressed at %lu", millis());
    on_release:
      - lambda: |-      
          ESP_LOGW("button", "release at %lu", millis());

stevemann · May 7, 2023, 1:08pm

Thanks for the code. I did open it up and found this:

Putting it back together was a bit of a challenge: getting the cable plugged in and not losing a spring.

Plugging it all in:

This did connect a UART and the PC reported it as COM33. Running Termite and pressing the reset button gave me this:

ESP-ROM:esp32s2-rc4-20191025
Build:Oct 25 2019
rst:0x1 (POWERON),boot:0x8 (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x3ffe6100,len:0x19c4
load:0x4004c000,len:0xc9c
load:0x40050000,len:0x2ce0
entry 0x4004c21c
[1B][0;32mI (21) boot: ESP-IDF v4.3.1-29-ge493a4c30e-dirty 2nd stage bootloader[1B][0m
[1B][0;32mI (21) boot: compile time 16:57:12[1B][0m
[1B][0;32mI (22) boot: chip revision: 0[1B][0m
[1B][0;32mI (26) qio_mode: Enabling default flash chip QIO[1B][0m
[1B][0;32mI (31) boot.esp32s2: SPI Speed      : 80MHz[1B][0m
[1B][0;32mI (36) boot.esp32s2: SPI Mode       : QIO[1B][0m
[1B][0;32mI (40) boot.esp32s2: SPI Flash Size : 4MB[1B][0m
[1B][0;32mI (45) boot: Enabling RNG early entropy source...[1B][0m
[1B][0;32mI (51) boot: Partition Table:[1B][0m
[1B][0;32mI (54) boot: ## Label            Usage          Type ST Offset   Length[1B][0m
[1B][0;32mI (61) boot:  0 nvs              WiFi data        01 02 00009000 00006000[1B][0m
[1B][0;32mI (69) boot:  1 phy_init         RF data          01 01 0000f000 00001000[1B][0m
[1B][0;32mI (76) boot:  2 factory          factory app      00 00 00010000 00300000[1B][0m
[1B][0;32mI (84) boot: End of partition table[1B][0m
[1B][0;32mI (88) esp_image: segment 0: paddr=00010020 vaddr=3f000020 size=a9294h (692884) map[1B][0m
[1B][0;32mI (215) esp_image: segment 1: paddr=000b92bc vaddr=3ffc92b0 size=04098h ( 16536) load[1B][0m
[1B][0;32mI (219) esp_image: segment 2: paddr=000bd35c vaddr=40024000 size=02cbch ( 11452) load[1B][0m
[1B][0;32mI (224) esp_image: segment 3: paddr=000c0020 vaddr=40080020 size=bab80h (764800) map[1B][0m
[1B][0;32mI (361) esp_image: segment 4: paddr=0017aba8 vaddr=40026cbc size=125f4h ( 75252) load[1B][0m
[1B][0;32mI (378) esp_image: segment 5: paddr=0018d1a4 vaddr=50000000 size=00010h (    16) load[1B][0m
[1B][0;32mI (388) boot: Loaded app from partition at offset 0x10000[1B][0m
[1B][0;32mI (388) boot: Disabling RNG early entropy source...[1B][0m
[1B][0;32mI (400) cache: Instruction cache 	: size 8KB, 4Ways, cache line size 32Byte[1B][0m
[1B][0;32mI (400) cpu_start: Pro cpu up.[1B][0m
[1B][0;32mI (414) cpu_start: Pro cpu start user code[1B][0m
[1B][0;32mI (414) cpu_start: cpu freq: 240000000[1B][0m
[1B][0;32mI (414) cpu_start: Application information:[1B][0m
[1B][0;32mI (419) cpu_start: Project name:     knobscreen2.4[1B][0m
[1B][0;32mI (424) cpu_start: App version:      4676002-dirty[1B][0m
[1B][0;32mI (429) cpu_start: Compile time:     Jan  8 2022 18:14:16[1B][0m

So, we’re making progress…