Run Micro (not Pro Micro) at 3.3V *AND* USB

Other Hardware Displays
1

Hi all.

I have a 2.4" TFT (ILI9341 based) that runs at 3v3.

I don´t have money nor time to buy level shifters, and instead of mount 5+ resistor dividers (for minimal display funcionality - no touch), I´m thinking in power Micro at 3v3, but without loose USB comunication (for MIDI USB usage).

This setup at 5V is working with a 16x2 LCD, but a TFT will allow show much more info.

So...

My initial thinking was power 3v3 in Vin "pin" and try... but in moment I connect the USB, 5V will be the "standard" voltage for all circuit (and maybe blow arduino or someone else...).

Alternative: Making a special USB w/o 5V line, just D+, D- and GND, will work?

Any ideas more, pls?

Adrian

2

I would use an LM7803 and power the 3v3 devices. You could flesh out two power rails using this method, but make certain you don't draw too much power from extra components. The second issue is difference in logic levels, there are methods around this though, like using a signal diode linearly to the load

3

You cannot run a standard 16 MHz Arduino Micro at 3.3V, you'll have to lower the clock speed.

See §29.6 in the datasheet.

Pieter