Reading Si7021 firmware version

Device Code
1

I have three devices which I believe all have the same Si7021 sensor, but I need to confirm this, since we’re seeing what may be 3 degree differences in temperature readings between the 3 devices (I’m aware of the +/- 0.4 C accuracy).

The Silicon Labs documentation shows command codes (2 of them) to read the firmware version, but I don’t know how to properly send two command codes to the sensor and then read the resulting firmware revision.

I’ve attached a screenshot of what they’re indicating needs to happen.

2

I’m thinking the following should do the trick, but I don’t want to mess up my Si7021 by writing something that’s potentially damaging.

`
//used to print hex numbers
function phex(s) {
local h = “”;
for(local i=0;i<s.len();i++) h+=format("%02x",s[i]);
server.log("phex conversion: "+h);
return(h)
}

//Reports the firmware version of the Si7021 sensor
function readFW() {
    _i2c.write(_addr,"\\x84"+"\\xB8");
    imp.sleep(0.1);
    local reading = _i2c.read(_addr, "", 1);
    while (reading == null) {
    reading = _i2c.read(_addr, "", 1);
    return reading;
    }
}`

I could then print the results with something like the phex function