I2C CRC mismatch question

Adam Jimerson

Hello,

Hopefully someone here can help me out, I have a SHT31 temperature and humidity senor connected to my Omega2+ through the ADC dock.

Using i2cdetect I can see the device:

root@Omega-36E5:~# i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- 44 -- -- -- -- 49 -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

(the device is 0x44)

The problem is when I try to read the sensor data from the device using a piece of example code I get a CRC error

package main

import (
	"log"

	i2c "github.com/d2r2/go-i2c"
	sht3x "github.com/d2r2/go-sht3x"
)

func main() {
	// Create new connection to I2C bus on 2 line with address 0x27
	i2c, err := i2c.NewI2C(0x44, 0)
	if err != nil {
		log.Fatal(err)
	}
	// Free I2C connection on exit
	defer i2c.Close()

	sensor := sht3x.NewSHT3X()

	temp, rh, err := sensor.ReadTemperatureAndRelativeHumidity(i2c, sht3x.RepeatabilityLow)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Temperature and relative humidity = %v*C, %v%%", temp, rh)
}

The error in question is CRCs doesn't match: CRC from sensor (0xFF) != calculated CRC (0xE1) I don't know how to check if I have a bad SHT31 or if the issue is with the library I'm using. I have not been able to work out how to manually read the sensor data using i2cget to test that way (mostly due to my unfamiliarity with it).

root@Omega-36E5:~# i2cget -y 0 0x44
0x80
root@Omega-36E5:~# i2cget -y 0 0x44 0x80
0x80

Any good way to rule out bad hardware?

Adam Jimerson

It looks like this was an error in the library that I was using as the libraries author has confirmed they are seeing the same thing when they tried to read from the same kind of sensor.