Is the 3v3 port regulated?

I have a serial LCD operating at 3.3v.
can i safely use the gnd & 3v3 port to operate it?

the lcd has only RX, so when i use:
hardware.uart12.configure(9600, 8, PARITY_NONE, 1, NO_CTSRTS);
pin1 is for transfering data to the lcd, but pin2 is out of use now? As i dont have TX wire…so does it mean i cant use it at all?

The answer will depend on which board you have plugged the Imp in to. There could be some host boards with enough extra current to supply the LCD and others will not. The Imp needs up to 400mA at times. Do you know how much nominal and max current the serial LCD requires? The 3.3V is and must be regulated.

You can use the UART without using all of the pins - at least usually you can. I don’t know if it is possible to reconfigure the unused pin later to be something else but…maybe it will be. That is something you can try and see for yourself if someone doesn’t chime in with an answer.

If I use
hardware.uart12.configure(9600, 8, PARITY_NONE, 1, NO_TX);
will Pin2 be free for use, even though i did uart12 (1 & 2) ?
when backlight is on, it needs about 60mA.
I dont have much devices I need,
1 LED, 1 LCD, a button for on/off and turning on/off a relay.
If Ill demand more than its capable of, 400mA, what will happen? :slight_smile:

Once i receive all my parts, including the breadboard im waiting for, I’ll take the 5v from the power supply, regulate it to 3.3 and operate the lcd from there. so that the only connection with the board will be the pin to communicate with the lcd. i guess it will be much better?

your connection will be the line for communication AND the ground wire : )
for Pin2, just try it. After configuring the uart, try configuring pin2 as an output, then change it and just see if it still works. nothing like trying things in real life to learn.
60mA is pretty low requirement. I am not positive what happens when too great a load is applied. it could be the regulator will begin to overheat. it could be the regulator will fail. Someone else may know - it is such a common principle that a web search will probably turn up some things. I like adding “forum” to my web searches.

The DCDC on the april board (and sparkfun’s equivalent) is 500mA, so there’s about 100mA available from the 3.3v pin. Should be fine to drive your LCD.

If you draw more than is available, the DCDC will shut down. Things should not get damaged.

As mjkuwp94 notes, you always need a ground reference for communication. You’d have 3 wires - GND, 3V3 and serial tx - going to the display.

If you’re only using TX (pin 1) then you should configure with NO_RX. Pin2 will then be free for any of its available functions.