Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

[SOLVED] Problem with P89V51RD2 interfacing with GSM module (SIM900)

Status
Not open for further replies.
g_shyam1682

g_shyam1682

Full Member level 4
Joined
Jan 11, 2010
Messages
204
Helped
53
Reputation
106
Reaction score
43
Trophy points
1,308
Location
Udaipur-Rajshan-India
Activity points
2,538
Hello friend,

I have one problem with my GSM base project.
In my project, 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,
 

The built in Low Dropout Linear voltage regulator allows you to connect wide
range of unregulated power supply (4.2V -13V) at supports 1 A.

Connect the GSM Modem to a PC Com port using a MAX-232 circuit or TTL-RS-232/TTLUSB
and Power it Up.

You can use 12 V at 1.5 A both micro controller circuit and GSM Module.

And interfacing the module with the using MAX232 circuit.

You can't directly communicate with the micro controller.

This link having SIM900 Datasheet. Its having MAX 232 Circuit.

https://www.rhydolabz.com/documents/gps_gsm/sim900_rs232_gsm_modem_opn.pdf

I hope its helps you.
 

Thanks for your reply, amayilsamy

but here i talk about direct communication between SIM900 GSM module (From SIMCom) and micro, not GSM modem. Power supply and all other need circuit i will design myself.
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.


Regards,
 

Hello Friend,

Please help me to design Microcontroller ( P89V51RD2 - 5V) direct interfacing with SIM900 (From Simcom, 4.2 V) Circuit myself.

Regards,
Ghanshyam.
 

g_shyam1682 said:
Hello friend,

I have one problem with my GSM base project.
In my project, 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,
Click to expand...
it directly communicate.no issue of 4.2 volt
 
Thanks zia,

Now i am able to communication directly, without any circuit in between.
Now i have one more problem, How to get SCID no. from SIM900a. I google the internet and i find out AT^SCID command to get SCID, but this command is not supported in SIM900a.
Please help me to get SCID no from SIM900a.

Regards,
 

may u please mention why u want to use csid, in sim900 for IMEI Number AT+GSN is used and for sim number AT+CNUM? is used (If an Error occurs, number is not set on SIM card)
 
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top