Hi, it seems i'm loosing my eyes... I can't find anything about 5V UART operation. I hope anyone of you can tell me more about this or where i can find information about it. I'm walking thru the datasheet for hours...
The datasheet you are referring to is for the MAX3232 (Maxim)?
Actually, what are you wanting to do? Run the MAX3232 off 5V rather than 3V3? The web master has Google Search on this site now, so you could search for a previous discussion on the <MAX3232>
UART on mini2440 has 3V3 levels. MAX3232 is placed on board for converting TTL (3V3) to RS-232 (12V) for connecting board to PC through onboard DB9 connector. If you want to connect you device with 5V TTL to mini2440's UART you need level converter (MAX3232, ADM3222, ADM3202 or analogs). If you device works with 3V3 TTL you can connect it directly.
The UART on the controller is tolerant up to 7Vdc...according to the specs sheet of the part itself. Since Vdd is 3.3V, anything below the magic smoke point (7V) will work. I've tested with 5V already, and it works just fine.
The UART on the S3C2440? Could you state what page in the datasheet? I scanned the whole datasheet for "UART" and "7V" and found nothing.
I apologize, it's 5.5V. I was looking at another IC while typing. In schematics of the mini2440 on pdf page 6/9, you will notice the IC as: MAX3232SOP. If you go to here: http://datasheets.maxim-ic.com/en/ds/MAX3222-MAX3241.pdf, you can see that the IC is tolerant up to 5.5V. Pages 7-11 of the datasheet proves this.
The MAX3232SOP is not a UART it is a "+5V-Powered, Multichannel RS-232 Driver/Receiver". The UART is peripheral on the S3C2440 chip and as far as anyone has been able to determine whether or not it is 5V tolerant . . . is still a mystery.
Mini2410 - according to S3C2440.pdf, only "t10" type inputs are 5V tolerant. RXD0 is "t8" type, which means UART is not 5v tolerant. You should not exceed 4.8V (Absolute maximum rating page). Mini6410 - S3C6410X.pdf doesn't mention 5V tolerant inputs at all. Tolerance for 3.3V inputs is a bit lower - 4.6V.
In that case, 2x D1n4148 in series or a large resistor should do the job. I forgot to mention that my setup does have a resistor in series.