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AT commands, uart, GSM module

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sloso

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hi evrybody,

I have GSM module motorola g24l, I wanna write some AT command via HT but it doesn't work. Im using RS232/USB converter. First I'm trying write just command "AT" I should get reply "OK". But I didn't get anything.
(on HT br 9600, data bits:8, parity:none, Stop bits:1 and flow control none). For to write AT command I set on HT in sections(file->properties->settings ...) ASCI II sending : "Send line ends with line feeds" and "Echo typed characters locally".

Im working really first time with AT commands...maybe Im doing something wrong way???
Can u help me pls? Thank u
 

ckshivaram thanks, but loopback test works fine...any other suggestions?
 

You have to use a MAX232 or similar RS232 to TTL level converter.
 

yes yes Im using MAX3238.
 

Maybe the modem is already configured in some baud rate, not auto baud rate. So try different speed. Eg 2400n1, etc.
 

can you do AT&F and then AT&W .

this will reset the modem to default factory settings. then you cam start from the beginning by setting proper baud rate and other specific commands

---------- Post added at 07:37 ---------- Previous post was at 07:35 ----------

Disable echo ,and see if you can see AT printed on the terminal when you type AT..
 

hi evrybody,

I have GSM module motorola g24l, I wanna write some AT command via HT but it doesn't work. Im using RS232/USB converter. First I'm trying write just command "AT" I should get reply "OK". But I didn't get anything.
(on HT br 9600, data bits:8, parity:none, Stop bits:1 and flow control none). For to write AT command I set on HT in sections(file->properties->settings ...) ASCI II sending : "Send line ends with line feeds" and "Echo typed characters locally".

Im working really first time with AT commands...maybe Im doing something wrong way???
Can u help me pls? Thank u

Hi, i am facing the same problem. Did you manage to solve this? Thanks!
 

Hi nyl,

I did not solve it! Anyway I believe there was a hardware issue. I made PCB for plug g24 myself, and I am sure that problem was there. Instead g24l I was working with Siemens cell phone, which was using as GSM station. With this phone everything works properly.
 

Thanks sloso for your quick reply! I did the PCB myself too. How did you power up the pins to switch the G24L on? I'm thinking thats where my problem is, currently i'm using a PIC to drive the pins. Not too sure if CTS_N and RESET_N need to be driven manually or just ON_N or IGN as written in operating instructions.
 

I am not sure about it as well. I would say they should be driven manually...but as I said I am not sure
...I was working on it more than 1year ago I don't remember it very well...
here is some advice from datasheet(probably u already know it):



ON/OFF
It is important to note that the ON_N signal voltage level is different between the
modules.
In G24 the ON_N signal is referenced to the 2.75V logic level. In G24-L the ON_N signal
is referenced to the supply level VCC (3.3V – 4.2V). It is important to follow the
Developer Manual design recommendations for this signal.
The G24-L power-on timing sequence may be different than G24. This may be noticed in
the interface signals waveforms during the power up process. The signals logic state will
operate as expected after the power up process is complete and the module is fully
operational (usually after the UART is enabled).
The G24-L does not power-on automatically, for a short period, when an external power
supply is connected, unlike G24. The G24-L will only power up if the ON_N or IGN
signals are activated.
 

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