The UART slot has 4 pins - TX,RX,5V,GND. What is the purpose of 5V and GND pins? Should i pull up TX an RX pins to 5V? If I connect the AVR microcontroller to mini6410 UART may i just connect rx-tx, tx-rx pins? Will it work?
I guess the 5V and GND pins should supply an externally connected level shifter like the MAX232 is. And yes, connecting rx-tx and tx-rx between the S3C6410 and your AVR controller should work. Due to level differences (maybe the S3C6410 does not like 5 V levels at its input lines) you should add a series resistor between your AVR output (Tx) and the S3C6410 input (Rx) line (to save the overvoltage protection in the S3C6410).
Thanx for the answer )
I would strongly suggest NOT connecting the two directly together. See all the threads on <5Volt tolerant> Either run the AVR off 3V3, some of them do OR put in a level translator. People seem to get away with it on the mini2440, but mini6410 . . . who is the first to find out that is doesn't? Series resistors and preferably a 3v3 Zener to ground to limit the voltages before the internal diodes kick-in is an option. Maybe, someone with a better line into Samsung support could get some answers out of them. We only buy 100s to 1000s of the S3C2410 a year.
With an 4k7 series resistor you do not overload the internal diodes (5 V - 3.3 V - 0.7 V = 1 V -> about 200 ľA. So, there is no problem to connect these two processors in this way. The other way round can be a problem: does the 5 V AVR recognize a 3.3 V level as high? But it is a CMOS device, so everything above 2.5 V should be seen as high level.