GSM/GPRS module and arduino

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GTM900_Interfaces.pdf (1028409Bytes)
AT-Command_Reference.pdf (944312Bytes)
2_2.jpg (40257Bytes)
30.jpg (47257Bytes)
3.jpg (284863Bytes)
4_1.jpg (36473Bytes)

Hello

I solved the communication with gtm900-b using a "USB to TTL serial" converter

it gives the right response.when I turn the module on it sends:

"AT-Command Interpreter ready

OK"

and also other commands work properly.

but still when I use ARDUINO serial monitor to communicate it just receives:

"AT-Command Interpreter ready"

without "OK" and when I try some commands like "AT+CGMI" or any command

it just repeats the command

I don't know what's the problem and how to solve it

if I got the answer I will post it here 

thanks :)

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As Duane pointed out,

we need some links to your actual hardware. Searching for the GTM900b the first hit was a datasheet, but, it is solely for the GSM board and not the blue board it is sitting on in your pic.

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thanks for your attention my

thanks for your attention my friends :slight_smile:

the GSM Module is sitting on an extra board which has pins named :

VCC G_R GND on the yellow part

EAR+ EAR- MIC+ MIC- in white part

p20 p21 p22 … p27 in red part

and VCC M_R M_T GND in the blue part

my problem is :

1.the only datasheet on the web is just about the GTM900-B board not the board stock under it

2.I don’t have any information what p20-p27 pins do,and how to connect the board to serial and 

programm it using AT commands 

I just know G-R and G_T is about GSM

and M_T M_R is about MCU

what should I do?

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(No subject)

untitled.jpg

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Based on your extra info and the datasheet.

I would guess you are correct about talking to the modem via the G_T and G_R lines; TX and RX for the modem or where you send your AT commands. p20-p27 “may” be the 20 - 27 pins as labeled by the data sheet. However, it seems odd to me that pin 28 was not broken out as well.

Since the module itself has 2 serial ports, you could always try talking to one and then the other to find out which one listens properly. Barring that, you really need to get a datasheet for the blue board to know what pins are broken out.

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thanks for your comment

thanks for your comment Birdmun :slight_smile: yes you’re right 

after a long long time I could finally know about the pins…

I’ve got a new problem …

I used to communicate with the module with a usb to serial converter module

and I spoke with the board setting the settings and etc.

but when I use my Arduino UNO serial I cannot set the reset command

I don’t know what to do …

 

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So basically the new problem
So basically the new problem is identical to the old problem that you initially wrote about?

I’d love to help you, but I’m not willing to learn Persian just to do so.

Can you find information on that board in English? And put those links up.

These boards are designed to be easy to use.

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Thanks for your heartening

Thanks for your heartening support…yes of course …unfortunately there isn’t any Persian or even English support for that expensive product but thse I did mention ,but Ive found something about it that I’ll tell you :

 

 

 

as shown in this picture it has tho important sections named GSM and MCU,

each one has 4 pins

Vcc,GND,M-T(transmit),M-R(receive) for MCU

and Vcc,GND,G-T(transmit),G-R(receive) for GSM

I work with GSM for now and I became able to get

a good response just once…I mean for the first time

I could reset the settings and give commands to it.

but unfortunately for the second time I couldn’t reset

that Repeating feature-which repeats every command or "string"

that I give to it using serial port - and I don’t know where is the problem

or how can I totally Reset the hardware (to fix that) …

any Information about AT Commands is written in AT command reference

which I had uploaded here under the picture

and also the GTM900’s hardware reference which belongs to

it’s central cheap …

and thank you so so much again for your attention :slight_smile: <3

 

 

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Voltage problems?
You said it worked with a usb to serial cable.

The gtm900 module has a max voltage on any i/o pin of 3.5 volts, p. 18 of the spec sheet. Unless the board under it contains level shifters, the Arduino may have done nasty things to it.

Is your usb-serial cable 3.3v or 5v?

Also it may have to do with the serial protocol used.

At this oink I’m just guessing.

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it doesn’t give any

it doesn’t give any responses using 3.3 V power

I used 5 volt power and arduino serial

unfortunately it still Echo’s all commands

even the ATE0 which is supposed to turn off

the Echo,and even the ATZ0 which reset’s the whole 

module settings :frowning:

thanks 

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Arduino Code

HI dear friend

Thank you for bespoke information

I had a similar problem whit GTM900-b

Is it possible, for example, put a sample GTM900-b Arduino code ?

and this is my email: [email protected]

With gratitude