LCD screen

My team has recently purchased an LCD screen, and we would like to have it display the pressure remaining in our pneumatic tank. My question is if that is even possible.

The VEX system does not include a sensor to measure pressure. The best you will be able to do is an estimate based on the number of times you operate the pneumatics. Perhaps, through testing, you determine that after 20 actuations the pressure has dropped from 100psi to 50psi, you could count the number of actuations in the code and display an estimate based on that.