This page is intended to document the actual method to WBo2 calibration for Vems 3.x process in one location in an easy to understand format for use with a windows box and MegaTune

Instructions for calibrating WBO2

These instructions are for bench calibrating your WBO2

There are two steps.

Calibrating pump_zero

This portion is a non-issue if you purchased a v3.3 and got an email with the pump_zero value in the email from the webshop.

You will be changing this value[ Highlighted box in MegaTune ]


[see photo] of the WBO2 connector [see photo]from the EC-18[photo] and measure the voltage. [Overall cartoon]

This voltage is "as close to zero as possible"

Free Air Calibration

Now that the pump_pwm_zero has been set you are ready to do the free air calibration. You will be changing the config.wbo2_calibration value [ TODO: Highlighted box in MegaTune ]

mde02 can also turn it on.

Manmlp07 shows output

changes for pump cal dont take effect until you reboot v3.x. The commanded current resolution is appr. Istep= 7mA / 256 = 27uA steps. Since we usually measure voltage (usually from pump- as base, not from GND), so the acceptable tolerance can be expressed in a voltage:

5V / 256 = 0.019 V / bit
+/-20mV is minimum
170 changed to 20.0 (3.824)
175 changed to 20.3 (3.843)
180 changed to 20.5 (3.863)
185 changed to 20.9 (3.882)
186 changed to 21.0 (3.882)  
190 changed to 21.2 (3.902)

minicom in r30


Man moves to comm mode

mlp07 switches to WBO2 related LCD-page

mll displays content (in terminal, so you can see even without real LCD)

byebye ends terminal mode and returns to megatune

I guess we should recommend a starting value (RCal=115 Ohm or so), and get the user read the O2% in free air. We make an O2%-reading => wbo2_calibration table which the user can look up => voila: WBO2 is calibrated in 1 step.