# ORP 501Z Problems calibrating

Hi guys,

I have a Wemos D1 R2 with it’s A0 hooked up to the yellow wire, it’s 5v hooked to the red wire, and the GND to the black wire. I upload the ORPSensorSample sketch from the Wiki, changing only the orppin to A0, and I can’t for the life of me figure out how to get this thing calibrated based on the instructions on the Wiki so I don’t know if it’s a bad probe or what.

This step is so amazingly unclear when things don’t work; (* Step 4. Take off the interface of probe cable and continuously press the Black Button on the sensor to reset.) For example, before I unplug the probe wire the value I’m seeing when the solution is dipped in 225mV is -883mV at the moment while hooked to the Wemos 5V, GND, and A0, while running through the Analog Signal Isolator board. When the instructions say to continuously press the black button… Does that mean repeatedly, or hold? Continuously would mean to hold, repeatedly would mean to press over and over, and then for how long? Because when I unplug the probe wire the Arduinos reading goes to 1978mV, and when I press the button and hold it, the reading goes to -1247mV while I’m holding it, but the moment I release the button it jumps up to -3000mV. If I repeatedly press it the button I get values from 1300mV to 1900mV.

It really is tough using these guides when there’s only a single example, because you have no idea if your device is broken because it isn’t doing exactly what the example shows it should be. For instance I’m expecting to see some kind of an offset mV that is near the -11 in the example. If my offset is actually 1200 or something like that, that is so far out of range I would not ever think that it’s correct. What range is the offset expected to be for this at 3.3 and 5v?

If I have ORP 225mV solution, could we just simply put the probe into that solution and then set the offset to whatever the difference is? Does that mean that all of the other values would work?

After programming the Arduino with the sketch, the Serial Monitor starts and just has all sorts of mV values from low 100s to 1900. The thing is just sitting all alone on the table with nothing else hooked up at this point because I’ve removed EVERYTHING else on my entire project to try and isolate this issue. I have ORP 225mV solution as well, no idea what the heck to do here because nothing is acting like the wiki explains so I’m at a loss. I even have purchased Analog Signal Isolator boards and those seem to give only more issues.

Sorry in advance, super frustrated with these analog sensors and the Arduinos just giving absolutely inconsistent readings.