sim900 interface with pc and max232

[emaro]

hello,

I'm working with the GSM/GPRS sim900. I want to interface the module with PC. in this datasheet page 7 & 8 the manufacturer recommanded max3221 i saw too many people saying they used max232 for level adaptation and it worked well for them. i don't understand But the max232 levels is rs232 => TTL/CMOS (5v) and the sim900 cannot communicate with 5V (it communicates with 3V max). how is this possible??? how this could be done without damaging the module ??

Thank you

 

[irfan ahmad]

give it 4.2 v or 3.7 v from mobile phone battery.

 

[speedEC]

If you are using only Module and want to communicate with PC hyperterminal, you have to use converter IC as mentioned in the datasheet only. MAX232 will damage the SIM900 Module. Also, how do you powered the GSM Module? its operating voltage could be 3.2v to 4.8v, I hope.

 

[sokrad]

hello,

I'm working with the GSM/GPRS sim900. I want to interface the module with PC. in this datasheet page 7 & 8 the manufacturer recommanded max3221 i saw too many people saying they used max232 for level adaptation and it worked well for them. i don't understand But the max232 levels is rs232 => TTL/CMOS (5v) and the sim900 cannot communicate with 5V (it communicates with 3V max). how is this possible??? how this could be done without damaging the module ??

Thank you

You can't use MAX232, instead use MAX3232 for interfacing SIM900 and PC.
SIM900 has VDD_EXT output pin, which can be used for powering logic circuits.
Therefore connect MAX3232 Vcc (VCCmin = 3V, but it will work) pin to SIM900 VDD_EXT pin.
All other pins connect according to datasheet recomendations.