Trashed proprietary ESP8266MOD temperature monitor - how to repurpose?

ESPHome
1

Hi all,

I found this temperature monitoring device in an e-waste bin recently. The manufacturer’s site gives the specifications only and it seems you need to have a cloud account to get any more information or use it at all.

After removing the bottom housing, it runs on an ESP8266MOD (ESP-12F). The board has a 5V barrel power input, two 3.5mm inputs for DS18B20 one wire thermometers, a microUSB port (which testing reveals is only used for 5V power and seems to have no data function), a reset button and a Wifi status led. Some photos (MAC address blurred):

IMG_6764
IMG_67641920×987 184 KB

IMG_6765
IMG_67651920×997 237 KB

IMG_6766
IMG_67661920×1441 197 KB

Holding reset puts it into Wifi direct mode and connecting to the hotspot only allows for connection to another Wifi network. Once it joins Wifi, status LED goes solid green with orange flashes every 5 seconds, port 80 is opened to give a basic HTML page that reports Wifi connection information (SSID, channel, signal strength) only and provides input to change Wifi network credentials only; it does not report temperature data on this page. If Wifi credentials are wrong, status LED is solid orange.

Using clip leads, attempted to flash with CH341 UART (pin16 - to Rx, pin15 to Tx, pin12 shorted to GND, pin9 to GND, pin8 to 3.3V) but cannot get the device recognized. Holding the reset button while powering on does not put it into programming mode.

Can this be repurposed and how to program?

2

I don’t know how you count those pins…
Wire it like this and power the module from it’s own power source.

TX ↔ RX
RX ↔ TX
GND ↔ GND
GPIO0 → GND

3

This worked, thanks! The connection to 3.3V was not necessary to flash.

Any ideas how to figure out which GPIOs the A & B temperature probe inputs, USB data lines, reset button and 2-color LED are mapped to?

Tried a one-wire scan for the DS18B20 that came up empty:

12:14:00.823][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.823][C][gpio.one_wire:022]:   Pin: GPIO3
[12:14:00.823][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.823][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.823][C][gpio.one_wire:022]:   Pin: GPIO4
[12:14:00.823][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.838][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.838][C][gpio.one_wire:022]:   Pin: GPIO5
[12:14:00.838][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.846][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.846][C][gpio.one_wire:022]:   Pin: GPIO9
[12:14:00.846][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.861][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.862][C][gpio.one_wire:022]:   Pin: GPIO10
[12:14:00.862][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.874][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.874][C][gpio.one_wire:022]:   Pin: GPIO12
[12:14:00.874][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.887][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.887][C][gpio.one_wire:022]:   Pin: GPIO13
[12:14:00.887][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.900][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.934][C][gpio.one_wire:022]:   Pin: GPIO14
[12:14:00.934][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.934][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.934][C][gpio.one_wire:022]:   Pin: GPIO15
[12:14:00.934][W][gpio.one_wire:082]:   Found no devices!
[12:14:00.934][C][gpio.one_wire:021]: GPIO 1-wire bus:
[12:14:00.934][C][gpio.one_wire:022]:   Pin: GPIO16
[12:14:00.934][W][gpio.one_wire:082]:   Found no devices!
4

If you have multimeter, it’s simple to measure resistance between component and all the gpio pins. DS18B20 sensors likely share the same pin.

5

Making progress on this device and gotten it to report temperature data. Using the multimeter, there is continuity with Vcc, GND and Data to both one-wire inputs. The data line (ring of 3.5 mm jack) has continuity to GPIO2 only.

Probed one-wire bus to get address of DS18B20. Logs revealed the address of the one plugged in thermometer and from there was able to enable output as needed with the following code:

one_wire:
  - platform: gpio
    pin: GPIO2
sensor:
  - platform: dallas_temp
    name: Temperature_1
    update_interval: 30s
    address: (bus address)
    unit_of_measurement: "°C"
    device_class: "temperature"
    accuracy_decimals: 1
    state_class: "measurement"
    icon: "mdi:thermometer"

LED and Reset button are proving challenging. Both have glue covering the solder points so the traces are obscured and then run into resistor blocks. I do not want to remove glue and damage the PCB in the process. There is continuity from some of the resistor blocks around the LED and reset button to ADC0 and GPIO16/WAKE (in addition to Vcc and GND for the LED) but so far no ideas on how to control these.

6

code a switch for all remaining free gpios and test which one controls the LED.

7

Great suggestion. GPIO15 on turns LED orange, off (default) is green.