Small Breakout for SIM900 GSM Module

By on May 27, 2011
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Some post ago we presented a PCB to mount the SIM900 module. The project is used in our GSM remote control and the Arduino GSM Shield.
The dimensions aren’t big (1.75×1.95 inches) but in some cases they are too important for a projects, so….

Small Breakout for SIM900 GSM Module

Small Breakout for SIM900 GSM Module - SIM

..we have developed a small PCB GSM module to build device like localizators (coming soon… :-) ), bugs or other small devices.

The Schematics

Small Breakout for SIM900 GSM Module - SchematicThe schematic is the same of the old module.

The printed circuit board, measuring about 1.35×1.5 inches, has a pin strips (10 pin x 2) used to connect with the circuit board of the remote control device.

Let’s now take a look at the electrical scheme, which displays the connections.
The pin 1 (ON/OFF) is used by a microcontroller to turn the GSM module on and off. The module is turned on or off according to the logical level applied to their PWR line (pin 1 of GSM1) . The PWR line is equipped with an internal pull-up resistance and is active at logical zero; therefore, in order to switch the cellular module on, the microcontroller sets PWR at a high logical level (contact 1 of the pin-strip) and causes transistor T2 to saturate; this transistor will then sets the PWR line at a low level. Remember that the power on or off signal is only a pulse of about 2 seconds.
Reset monitoring is handled similarly. The module can be reset by simply causing the microcontroller to send a logical 1 via the RST line, at which time the T3 transistor saturates and sets the NRESET line of GSM1 at a low level.
Let’s now proceed with UART’s control lines (i.e., TXD, RXD, DTR, RTS, CTS, DCD), which are connected to the external area through the pin-strip’s contacts, respectively, 12, 14, 10, 2, 4 and 6.
The audio device, with two contacts for the microphone (with differential input) and two more for the loudspeaker, uses contacts 15, 13, 11, 9, which correspond, respectively, to MIC1P and MIC1N (positive and negative of the microphone) and SPK1P and SPK1N (respectively, positive and negative of the loudspeaker). The RI signal (indicating incoming calls) goes out through contact 8 of the pin-strip.
In this case, the GSM connector modules’ antenna is a 90° MMCX directly connected on the printed board of the cell phone.
Let’s now talk about transistor T1, used here to locally control the cell phone’s reception LED: its base is polarized from the current logical level on pin 52 (NETLIGHT) for GSM1. The transistor’s collector is where the line to contact 3 of the pin-strip starts; this line is connected with the LED line, which the microcontroller uses to get information regarding the presence of GSM network as well as regarding the connection status of the module (e.g., whether the network is available or not).

The Pin Out

 







 

1

3

5

7

9

11

13

15

17

19

ON/OFF

LED

VRTC

ADC

SPK1N

SPK1P

MIC1N

MIC1P

VCC







VCC

2

4

6

8

10

12

14

16

18

20

RTS

CTS

DCD

RI

DTR

TXD

RXD

RST

GND

GND

 

 


The bill of material

[code] C1: 220 nF (0805)

C2: 100 nF (0805)

C3: 470 µF 6,3 VL (CASE-D)

C4: 470 µF 6,3 VL(CASE-D)

C5: 100 nF (0805)

LD1: led green (0805)

D1: –

R1: 15 ohm (0805)

R2: 15 ohm (0805)

R3: 15 ohm (0805)

R4: 10 kohm (0805)

R5: 4,7 kohm (0805)

R6: 10 kohm (0805)

R7: 330 ohm (0805)

R8: 10 kohm (0805)

R9: 4,7 kohm (0805)

R10: 10 kohm (0805)

R11: 4,7 kohm (0805)

T1: BC817

T2: BC817

T3: BC817

GSM1: GSM module SIM900

SIM: Slot SIM-CARD

– Antenna connector MMCX 90°

– Strip male 2×10 via 2mm







– PCB </strong><strong> [/code]

 

 

Download the GERBER of Small Breakout for SIM900 GSM Module

Download the DESIGN of Small Breakout for SIM900 GSM Module

About Boris Landoni

Boris Landoni is the technical manager of Open-Electronics.org. Skilled in the GSM field, embraces the Open Source philosophy and its projects are available to the community.

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115 Comments on "Small Breakout for SIM900 GSM Module"

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Vadim
Guest

This breakout board looks great!
Have anybody tried it (or SIM900 GSM shield board) in USA with AT&T?
Thank you.

Kishore
Guest

Can I replace SIM900 with SIM900A in the above schematic? Will it work?

BorisLandoni
Guest

SIM900A is a SIM900 un a breakout board, so no problem

Pratik
Guest

is this gerber file works with sim900A?

thanks
Guest
Thank you for the post! I have been reading the application notes on SimCom 900 and have noticed that you have put some interesting variations. I am just curious what were the design decision, simply parts (ie: availability, commonality etc…) or if there are other considerations, I too will only use data/sms: Keep in mind that I am an amateur and so any differences are a big deal for me to understand. 1). For the power switch you use two resistors (r9,r8), which you set to (4.7k,10k) and the application note puts them at (4.7k,47k). Is this simply because you… Read more »
thanks
Guest

Thank you for your quick response. I meant, can I use the 3.3v from arduino pro mini to power the device (with the board you have)? Or will it draw too much current?

If it does use too much current, can I add something to help allow for more “Amps” like bigger capacitors?

Ahmet Alpat
Guest
Hi Boris. Thank you for this great post. I want to use GSM Module to send SMS only. Nothing more. And i am designing my own board based on yours. It is going to be controlled by a low power MCU and i dont want to use pin strips. I just want to connect SIM900 directly to the MCU. Here is what i want to know; what should i do with the pins that i will not use -like mic, headphones etc? Do you have any suggestions about grounding, PCB and connecting the module to MCU directly? Thanks in advance
Ahmet Alpat
Guest

That’s great, thank you.

Ashwani
Guest

Hi All,

Accourding to my R&D 3.3 supply is not working fonr from ardu….

I have tried many times…not working..let me know if this works from your end.

I am looking to replace pic with atmega320 with 3.3 volt.

Regards,
Ashawni Sihag

Mahdi
Guest

Hello.
We need the .PCB file of this circuit for ProtelDXP. Can you send it to our email please?

Thank you

Ahmet Alpat
Guest

Hi Boris,

Is it possible for you to share the schematics file? .sch?

John Doe
Guest

Sorry for a noob question but which is pin 1 on the 20pin connector?

Ahmet Alpat
Guest

Can not we connect RST and PWR pins directly to PIC? Do we need BC817’s?

Ashwani
Guest

Hi Boris!

Hope you are doing fine.

I connected DTR pin and RI pin to microcontroller and then sim900 rx tx stopped communicating with microcontroller.

I was making DTR high and low to make sim900 sleep and wakeup.

Is something damaged inside sim900?

Regards,
Ashwani Sihag

k4
Guest

Hi,

Can this be used to monitor GSM frequencies ? Like being idle and looking at what is passing through the air ?

Thanks,

Jegan
Guest

Can someone help me out with the BOM for D1?

Goodgood
Guest

I need breakout board for Sim900B
Thanks

trackback

[…] sim900 te simple serial connection See pins : http://www.open-electronics.org/smal…00-gsm-module/ Reply With Quote + Post New Thread « Invertor for controling […]

Menuk
Guest

Thank you so much for this.I would like to use this design for my Kickstarter project.My project will be open source.

Thanks

menuk

Raghavendra M
Guest

Hello ,

Am facing problem with sim900a module some time its working fine and it will going to hang that time SIM_VDD voltage ll be low can u help me plz see the schematic wt i hav done.. plz see the image http://images.elektroda.net/99_1345187336.jpg

shams ul arfeen
Guest

SIR! i am trying to use sim-900 in ,my final year project with PLC dear sir kindly refer me to how to use and configure it?

BorisLandoni
Guest

What’s your problem?

Demonio Azteka
Guest

i there

i have any questions.

can i use this module with arduino without shield.

can i use this module without conect audio socket

im hope user this module only for GSM & GPRS DATA like sms or internet but no use de audio socket or lcd, then i wish a compac design.

thanks

BorisLandoni
Guest

Hi, yoes of course but you have to adapt the signal lever.
See the shield schematics to understand how connect it.

Brecht Vaelen
Guest

Dear,

I would like to connect this gprs-module to lpc1768, this is an arm-processor.

So I would have to write C/C++ files, Im currently using mbed.org but this library doesnt include gsm/gprs-files.

I need to send data like I would feed data to pachube/cosm.com

I would only receive a simple command like ‘reset the system’

Is it possible for me to use code from this:

http://code.google.com/p/gsm-shield-arduino/source/browse/branches/SIM908IDE100/?r=93

I would like to have a startcode to work with/modify
but starting from scratch would not be possible for my current programming skilllevel/time schedule

thanks if you can help me out..

ps: somebody told Im supposed to use sockets, is this true or false?

BorisLandoni
Guest

It’s not so simple.

trackback

[…] if you can help me out.. ps: somebody told Im supposed to use sockets, is this true or false? *http://www.open-electronics.org/smal…00-gsm-module/ Reply With […]

Guest
Guest

hy does this circuit can I use to control the relay by microcontrol atmega 8535?
thanks

BorisLandoni
Guest

Hi, the Small Breakout for SIM900 could be controlled with AT commands, so you can use any microcontroller

Guest
Guest

hy apakah rangkaian ini bisa dipergunakan untuk mengontrol relay lewat microcontrol atmega 8535?
terimakasih

bedu aja
Guest

hy does this circuit can be used to control the relay by microcontrol atmega 8535?
thanks

trackback

[…] build is a 128×64 OLED screen that replaced the old seven-digit, seven-segment display and a very small GSM module. The ancient PCB was discarded and a new hardware revision was created in Eagle based on an […]

trackback

[…] build is a 128×64 OLED screen that replaced the old seven-digit, seven-segment display and a very small GSM module. The ancient PCB was discarded and a new hardware revision was created in Eagle based on an […]

trackback

[…] build is a 128×64 OLED screen that replaced the old seven-digit, seven-segment display and a very small GSM module. The ancient PCB was discarded and a new hardware revision was created in Eagle based on an […]

Maurits Hartman
Guest

Hi,

I was just wondering about the circuit part that controls the on/off and reset pins. In the breakout, these are directly to the collectors of the transistors T2 and T3. In the SIM900 hardware design document (V1.01, page 23) however, there is a 1k current-limiting resistor between the collector and the pins. The document also mentions that the maximum current that can be drained is 0.3mA.

Shouldn’t your design be updated with these resistors? Or did you never had any trouble with it?

Maurits

BorisLandoni
Guest

we use a transistor, you can also use a switch. So no problem. it Works without problem..

Maurits Hartman
Guest

Thanks for the quick reply!

cl1d3
Guest

Is possible to buy completed module? If yes, what is price?

BorisLandoni
Guest
Sunny
Guest

Hi friends..we are the SIM900 completed mould distributor in HK and China.

Our MOQ is 1000pcs,update price is $10.5/pc ,anyone interested,please contact me by mail info@lyinternation.com and by Skype” sunnyleeyang”,hope to be partners to discuss the application of SIMcom mould..

BorisLandoni
Guest

We use a special forniture, with DTMF decoder software, antijammer and cell locator.

emaro
Guest

hello, for esd protection you used TVS diodes, i can’t buy this type of diodes because of its non availability in shops. can i use zener diodes, ceramic capacitors ? if yes what do you suggest (with values), thank you ! :)

BorisLandoni
Guest

Hi the diodes aren’t mounter in our breakout. They aren’t necessary.

TUSSHAR SAIGAL
Guest

demo code for arduino or a library ???

Roman
Guest

Hi,

What ttl level converter should I order to be able to use this module with 3.3v or 5v arduino?

Thanks

tolisn
Guest

Hi
How can we connect this module with a 5V arduino ? What level converter are required /

Jim Norton
Guest

Sorry for the possibly stupid question. Does this SIM900 GSM Module work in the USA and if so, what carriers?

I very interested in this for an embedded product being designed for the USA, but I don’t yet know all the acronyms or much about cellular technology.

Regards,
Jim

Gopalakrishna Palem
Guest

I believe SIM900 is quadband, hence suited for US.

http://gk.palem.in/

Vinit Jain
Guest

hey… i am working on eagle software for designing the same schemetic……….can anyone suggest me the the link of eagle library in which i can find the SIM900A module for designing the schemetic as i am not finiding it with my version…..

BorisLandoni
Guest

Hi, we don’t use Eagle, so I haven’t the library.
I’m sorry

samustafa
Guest

i need 900d ckt, does anyone has it??