I don't really need the LCD to work at 3.3V, it just would have been handy so I don't have to switch the power supply after programming.
Well, it clearly won't
, but during development you can leave the Pro Mini connected to and powered by the FTDI only, and the LCD (both parts) powered by the 5V supply. It would be nice
to know the current details and the behaviour of the 5V supply.
The Ampermeter part of my Multimeter is broken so I can't measure the current at the moment.
I did not bridge J7, the resistance between the J7 leads is 12 ohms.
Checked that out. Good.Must
be a newbie though - only one multimeter! Cost about $5, need at least
two (if only for simultaneous voltage & current readings) and clip
leads. Note: for currents in excess of a milliamp, the voltmeter should be connected on the component
side of the ammeter as the ammeter has a significant voltage drop; for currents less than 1 mA, the reverse is likely to be the case.
I'll try powering the arduino from 3.3V FTDI and the display from 5V, will post the result in a bit.
Isn't that a short to frame though?
Not sure what you mean. Don't make any sort of power connection between the Pro Mini and the display, but there must always
be a common ground connection between all parts.