I have so far been using some MAX3323EEPE chips for shifting between 3.3V and 5V logics on serial / UART communications. This is quite some stuff to solder on a PCB, and the chip is a bit expansive. I only do quite vanilla communications, such as up to 57600, absolute max 115200 baud rate.
Would this kind of shield:
https://www.adafruit.com/product/757
do the trick?
And this kind?
https://www.adafruit.com/product/395
Edits
- Edit 1: typical use: I am thinking about having a project built around a 3.3V micro-controller, but I will need to be able to talk to some 5V logics stuff too. I will have a 5V step-up converter on the design, so getting 5V is not an issue. Typically, I will need to talk to a RockBLOCK 9603, which seems to be rather 5V than 3.3V ( https://www.rock7.com/products-rockblock-9603 though not completely clear to me if it would be ok to power with 5V and talk through 3.3 logics level; but other things will definitely need 5V logics levels anyways, so good to put on board).
Best Answer
What are you connecting your UART/serial comms to?
The MAX3323 uses external capacitors to generate +5V and -5V, and uses those supplies to convert signals from the low-voltage side into signals which transition between +5V and -5V. It only requires one low-voltage supply to do this.
The shield devices you link to require an external supply ( +5V ) to be used, and will then convert your low-voltage signals into signals which transition between +5V and 0V
The shields will require an additional 5V power supply - and if the device you are connecting to is expecting -5V levels, they won't work.
Edit for use with RockBlock 9603:
The Serial interface on this device looks like you may be ok with 3.3V levels only - in which case no interface would be needed
from here - https://www.rock7.com/products-rockblock-9603