[SOLVED] call waitng facility in sim300 interfacing with 8051

[debabrta kar]

hi.. i am interfacing sim300 with 8051. how can i activate call waiting facility...i mean when modem recieves a call from one number and if i will call from another number to modem them the 2nd user must be in a waitng...

 

[g_shyam1682]

Hello friend,

Can you send me your interfacing circuit diagram.
I use P89v51Rd2 means 5V microcontroller and my GSM module (SIM900) is working at 4.2V, so how can i connect my Micro RX, TX which is at 5V to SIM900 RX, TX which is 4.2V support.

Please help me to design my circuit.
Thanks in advance.

Regards,
Ghanshyam

 

[debabrta kar]

as their not TTL compatible so in both side sim900 module and microntroller side u have to use max232 in both side......

 

[g_shyam1682]

Hello friend,

I think, Module Tx to Micro Rx line drive from module side, so need not any addition component and may connect directly.
For, Module Rx to Micro TX line drive from 5V (Micro side), so here i think we should use some type of resister divider circuit.

Please, Expert people comments on my suggestion.

Regards,

 

[debabrta kar]

sim900 operates in 3.3v as it has a arm microcontroller inside modem...so kindly check the voltage level whichi is not 4.2 and its 3.3.v.....

 

[debabrta kar]

can i get the number from which m giving a call to sim300.......please guide me.....

 

[g_shyam1682]

Hi friend,

Yes you can get phone no. from which giving a call. In incoming call, SIM300 generate URC code and send at UART with Phone no.

Regards,

 

[debabrta kar]

yes sir...thanx...but how to perform a call waiting service....