Hi,
I just ported BR’s bar30 pressure sensor library to pi pico and it is working fine… reports around 1 bar on bench. The specs say that the accuracy of this unit is around 240 cm (6.5 ft) but we dont have that much delta in our testing waters. For our pool testing, I think we’d initially go with the bar2 sensor as that would help us test the control logic better than the bar30… My question is: we also do not have a mount ready for the bar30/02 sensors so would it be okay if we just let it hang in our free flooded compartment or is it like only the front part of the sensor (forward to the o-ring) should be exposed to water while the back side (through which the i2c wires are coming out) should be in the watertight compartment ? I do see that there’s some kind of epoxy being used on the back hole… just wanted to check if we can just dip it in water as is with the o-ring assembly tightly screwed in place ? The other end of the i2c connection to mcu is via a hull penetrated hole that is sealed properly. thanks
Hi @nmam -
The Bar30 is not waterproof from the backside! Only the head of the bolt should be exposed to water pressure.
If you subtract the ambient air pressure on start-up from the reading, you will get the full potential resolution of the sensor when reading the depth.
Hi @tony-white thanks for the clarification… good that I checked here first before trying it out. Is there any other waterproofing method you’d suggest that would allow me to lower it to say around 10m depths without the usual mounting pattern? I came across this article where folks placed the pressure sensor inside a sealed ballon with no air… I guess that should hopefully work provided the baloon’s opening is sealed properly.
Hi @nmam -
The I2C interface of the Bar30 is not going to work well with a long cable… If you can keep the cable short, you could install the Bar30 on a WetLink splice kit and route it to the surface through a WetLink penetrator coming out the other end.
If you need to go a long distance, you might be able to fit a differential signal I2C adapter in to maintain communications over a few meters of cable. An active terminator at the sensor may also enable a long cable. Only testing will determine - let us know how it goes!
@tony-white I think wetlink splice kit should work well here. We will test with this, thanks. Also i2c wire length is not an issue at this point in time as with our build it would be just under a foot’s length from sensor to the mcu.