NUCLEO-G491RE communication with SIMCom SIM800A - Problems

[abhishek1991]

Hi,

Hope you are doing good.

I am trying to transmit "AT" command using USART communication to SIM800A(SIM.COM). 

I am facing errors, should I write a separate GSM module. 

Thank you.

[Andrew Neil · Accepted solution]

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@abhishek1991 wrote:

communication with GSM 800A - Steps Needed

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Simple:

1. Send valid AT command to the SIM800A;
2. Receive reply from the SIM800A;
3. Determine success/failure from the response, and proceed as appropriate.

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@abhishek1991 wrote:

I am facing errors.

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What "errors", exactly?

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@abhishek1991 wrote:

should I write a separate GSM module. 

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Modular software is generally accepted as A Good Thing.

However, putting code which "has errors" into a separate module will just give you a module which "has errors" - it won't, in itself, solve your errors.

https://community.st.com/t5/community-guidelines/how-to-write-your-question-to-maximize-your-chances-to-find-a/ta-p/575228

[abhishek1991]

Hi, 

My main code goes like this and below that is my usart code. I just want to transmit "AT" string get back OK from SIM800A. Can you please help me how to proceed further ? 

[Andrew Neil]

You've marked my previous post as The Solution - but it seems this is not solved yet?

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256#:~:text=If%20you%20accidentally%20chose%20the%20wrong%20post%20as%20solution%2C%20you%20can%20always%20revert%20this%20action%20by%20clicking%20%22Not%20the%20Solution%22

You still haven't said what were the "errors" you mentioned:

• compiler errors in your code ?
• "ERROR" replies from the SIM800A ?
• other ?

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@abhishek1991 wrote:

I just want to transmit "AT" string get back OK

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Forget about the SIM800A for now - just connect your UART to a terminal.

Can you see anything being sent from your STM32?

[abhishek1991]

Hi Andrew,

No, Not yet, I am working on it after usart is accomplished. Appreciate it. Thank you.

[Andrew Neil]

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@abhishek1991 wrote:

No, Not yet

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You mean not solved yet?

Then please un-mark the solution:

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256#:~:text=If%20you%20accidentally%20chose%20the%20wrong%20post%20as%20solution%2C%20you%20can%20always%20revert%20this%20action%20by%20clicking%20%22Not%20the%20Solution%22

What are you doing here:

    /* USER CODE END WHILE */
	  HAL_UART_Transmit(&huart2, txBuffer-1, size, HAL1TIMEOUT);

Why txBuffer-1 ??

Why are you trying to transmit the character before the start of the buffer ?!?

Similarly:

	  rxBuffer[20]=HAL_UART_Receive(&huart2, rxBuffer-1, 20, HAL1TIMEOUT);