ESPhome - SHT40 - CRC8 Checksum invalid at pos 1! 0xFF != 0xAC

ESPHome
1

hi, trying to get working the sensor sht40 (3,3V) from aliexpress:
https://www.aliexpress.com/item/1005008100316660.html?spm=a2g0o.order_list.order_list_main.161.6ba61802tlj10V

on ESP8266
but still getting error on i2c bus
[13:22:12][E][sensirion_i2c:026]: CRC8 Checksum invalid at pos 1! 0xFF != 0xAC
[13:22:12][D][sht4x:080]: Sensor read failed


i2c:
  sda: 4
  scl: 5
  scan: true
  id: bus_a
  #frequency: 100kHz was trying diff frequecy but still same error

sensor:
  - platform: sht4x
    temperature:
      name: "Temp"
    humidity:
      name: "Hum"
    address: 0x44
    update_interval: 10s

anyone got same errors and fix somehow?
thx a lot

2

How long are the cables to your sensor?

3

Maybe they sent you wrong option, sht30 or sht20
Edit: it would have different address so not the case if sensor is found.

4

3meters original

5

3 meters original cable and adress was found ok:
[14:46:40][C][i2c.arduino:071]: I2C Bus:
[14:46:40][C][i2c.arduino:072]: SDA Pin: GPIO4
[14:46:40][C][i2c.arduino:073]: SCL Pin: GPIO5
[14:46:40][C][i2c.arduino:074]: Frequency: 100000 Hz
[14:46:40][C][i2c.arduino:086]: Recovery: bus successfully recovered
[14:46:40][I][i2c.arduino:096]: Results from i2c bus scan:
[14:46:40][I][i2c.arduino:102]: Found i2c device at address 0x44

6

It’s very optimistic to think I2C sensor working with 3m wiring!

7

idk why it cant, i have i2c bme280 on like 6m utp cable without problems in diff scenario, or i am missing something?

sht4
sht4789×730 256 KB

8

that I2C is reliable for very short wiring, anything measured in meters is just question of luck.

9

i just cut it to like 15cm and still same error

10

If your wiring is solid (soldered?) and you already tried different frequencies, I’m out of suggestions. Your AE link states that the sensor has 10k pullup on board.

1 Like
11

Nice probe by the way. What’s the diameter? Can you see if the sensor inside has filter membrane?