MAX232 with Spartan-3 xc3s400

[dsMasoud]

I have started to make a development board like SPATAN-3 Starter kit of XILINX. I have to do this , there is no other choice for me please don't tell me you can buy it or something like this .
my reference is xilinix document ug130 which contains schematics of the board but there are some devices like MAX3232,.. which is not available for me and i have to replace them with another one.
my question is:
is it posible to use MAX232 with xc3s400?
if possible can i use the standard circuit of MAX232 which for example use with microcontrollers? or should modify it and make it suitable for 3.3v spartan-3?
please help me with your guides,links or schematic

best regards

 

[IanP]

It is possible to connect 3.3V devices with 5V devices ..
Attached is an example of such a circuit ..

Also keep in mind that MAX232 is purely 5V device, so you will have to supply it of +5Vdc ..

Regards,
IanP

 

[bis_]

Connecting 5V MAX232device input to the 3,3 V output from the Spartan can be done directly with out any problem (for security you can add serial resistor about 100 Ohm)
Connecting 5V MAX232 output to the 3,3V input of the Spartan requires small level shifting (Sparatn is not 5V tolerant). Simple serial resistor at the input line works as the proper "level shifter". This is not such elegant solution but cheap and it works. Please look at the PS/2 keyboard connection in the Xilinx oryginal any Spartan developements boards. This is exactly the same situation as you have with your MAX232. Another way is using integrated level shifters or IanP described transistors.

bis