CMOS to RS232

hey guys. how can i convert a RX/TX communication from CMOS to RS232...

can i use the MAX232 or i have to use something different??

look thats what it show me in the datasheet of the GSM module

so its the same to connect the module to the arduino i just have to use the RX and TX.. or i can use the MAX232

"CMOS" isn't sufficient description. If it's 5V CMOS, that's pretty much the same as the "TTL" converters that everyone talks about (it's been a long time since most projects have had real TTL chips in them! AVR chips have CMOS I/O, for example.) But one of the characteristics of CMOS is a wide range of operating voltages, and THAT'S what you need to be matching... Basically want a MAX232-like chip designed for whatever the operating voltage of your module is. For example, the MAX3222 works at 3.3V, and it looks like there are chips that handle down to 1.8V. Or you can do multi-stage solutions (MAX232 to get 5V, 74LVC to convert to whatever...)

Hoping everyone will forgive the third post of this...

RS-232 // Arduino Rx Tx....

Don't try to get away with connecting an "RS232" signal directly to an Arduino... there are REAL, potentially equipment wrecking issues here!!!

See the "Hardware" section, a little way down in....

Have a look at RS232/Arduino(etc) interface...

Wulfden PA4B $11

http://wulfden.org/TheShoppe/pa/index.shtml

That SP3238 appears to be a logic level (3.3V or 5V) to RS232 converter, much like a MAX232. That unidentified "MODULE" on the left could likely be connected directly to an Arduino without fooling around with the SP3238 or MAX232 or any other kind of RS232 converter. The only reason the SP3238 is there is to allow communication with a PC.

Just guessing from the undocumented image you posted, in the absence of any data references.

It seems possible (with the limited info available) that the "MODULE" is 3.3V and should not be connected directly to a 5V Arduino. If that is the case (yet to be determined) then you will still need some sort of circuit to allow communication between 3.3V and 5V logic segments. Or you could use a 3.3V Arduino board.

ok im confuced because i was trying to connect the MODULE directly to the arduino but i dont get any signal or something from the GSM and now i was cheking in the datashet of the MODUlE and it says

The serial port the debug port dont support the RS232 levels and it only supports the CMOS level. You should and the level converter IC between the DCE and DTE

so do i really need to convert using the MAX232

http://daffinz.com/education/downloads/Component%20Datasheets%20and%20Application%20Notes/GSM-GPRS-GPS%20Modules/SIM548C_HD_V1.01.pdf

im powering the module like that

and i was using the gps and all gps part works great but now the GSM is the Issue