Lack of serial data transmission by GSM sim300z

• Aug 6, 2011

• #1

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ma_ok36

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I'm working with the module sim300z.
Although the LED(net light) flashes, it does not send data via serial connections
Where is the problem do you think of?

 

• Aug 6, 2011

• #2

ckshivaram

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show the circuit diagram you are using?????

 

• Aug 8, 2011

• #3

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ckshivaram said:

show the circuit diagram you are using?????

Click to expand...

circuit diagram

 

• Aug 9, 2011

• #4

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alireza11361156

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My circuit has met the same problem.
It is possible the problems of poor nutrition module.
Does anyone have a solution?

 

• Aug 9, 2011

• #5

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ma_ok36

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I've used the regulator lm78h05k for Power module.

regulator output is 5V that two diode is placed in its path and voltage reaches 4.3 V.

 

• Aug 9, 2011

• #6

ckshivaram

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what is the voltage and current rating of the supply adaptor you are using? Sorry i have lost track of the original problem... if it is one single thread i can go back to see what it was and where it started, what are the steps we have done earlier...

1. replace Max 232 IC and try.
2. interchange Max232 tx and rx pin and try again.
3. check only for AT and its response as OK.
4. Hope the cable and serial port of the computer is tested before by doing loop back test..

---------- Post added at 12:34 ---------- Previous post was at 12:32 ----------

there is no need to use this regulator package, unless you use 5Amp supply source... modem should work with 1Amp power source too.....

 

• Aug 9, 2011

• #7

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This is all done but no result!!!

 

• Aug 9, 2011

• #8

nandhu015

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Does your modem responds to at command?

 

• Aug 10, 2011

• #9

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No it is not responding.
we examine the TXD pin by scope But observe very low amplitude pulses!!
Where is the problem?

 

• Aug 10, 2011

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alireza11361156

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When I sent "at" command through the COM port, TXD pin module pulses in the range of less than 0.5 V

 

• Aug 10, 2011

• #11

ckshivaram

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which is the MAX232 IC ( part number) you are using and what are the capacitors used for the charge pump pins????????????

 

• Aug 10, 2011

• #12

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max232cpe
+0902
whit 4 capacitors (1uf) for IC
what charge pump pins?

 

• Aug 13, 2011

• #13

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alireza11361156

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I do not know what pump pins.
Voltage on VCC pin is 4.4V and Voltage on SIM_VDD is 2.9V.
Voltage module is the problem?

 

• Aug 27, 2011

• #14

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I've set up the module so that there is a possibility of contact.
The data between the module and the PC (and vice versa) is not transferred.
Is there any solution?

 

• Aug 27, 2011

• #15

ckshivaram

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change the max232 in the modem side.... and try to swap the tx and rx pin if required... and try to see what is the correct baud rate of the modem.....

 

• Sep 4, 2011

• #16

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what is the sim300z default baud rate???????

9600 or 115200 ???

 

• Sep 5, 2011

• #17

ckshivaram

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its 9600 baud rate set as default..... you can check it with AT+IPR?

 

• Sep 6, 2011

• #18

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The problem here is that I can not send a command(AT+IPR?) to the module.
Default baud rate is 115,200 bits per second specified in the data sheet.

Is this a mistake?

 

• Sep 6, 2011

• #19

ckshivaram

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change the baud rate in the hyperterminal to 115200 and then send AT and see if it responds as OK
then send AT+IPR? it will print the default buad rate set, it should show as 115200...

then send AT+IPR=9600
it will send OK
then do AT&W

then change the buad rate of hyperterminal to 9600 and restart the modem by powering it ON again.. then if you type AT and get OK as response then your modem is set to 9600 baud rate...

when ever you want to revert to factory settings the give AT&F.

 

• Sep 6, 2011

• #20

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متشکرم
thanks
Microcontroller serial communication with the max no problem
But when the module is connected to the circuit max, we will not get any output on the COM port.