UART

[L C]

Posted on July 24, 2017 at 08:08

Hi!

I am study UART to communicate with PC.

My target is use PC like a terminal to input AND out message to STM32.

My code is using HAL library.

I want to operate code like below.

**************************************

ch = ''UART test\r\n'';

HAL_UART_Transmit(&huart1,(uint8_t *)&ch, 10, 0xFFFF);

***************************

But appear error when compile.

Please let me know your comment.

BR

[AvaTar]

Posted on July 24, 2017 at 08:54

But appear error when compile.

Are we supposed to guess which error, or what ?

[L C]

Posted on July 24, 2017 at 16:43

Sorry, Just be calling for meeting when posting.

The error message is 'Error[Pe144]: a value of type 'char *' cannot be used to initialize an entity of type 'uint8_t' E:\STM32\Project\UART\Src\main.c 83 '

I know that the data type is different.

But how do I do to convert it.

BR

[Tesla DeLorean]

Posted on July 24, 2017 at 16:54

So which line is 83? Please present problems in clear and complete fashion

char *ch; // It is a char pointer, right?

ch = 'UART test\r\n';

HAL_UART_Transmit(&huart1,(uint8_t *)ch, 10, 0xFFFF); // It is a pointer, you don't need the address of the pointer, lose the &

[L C]

Posted on July 25, 2017 at 02:42

Dear ALL

The screen dump with error message and source code are attached.

Please take a look and let me know your comment.

BR

[Tesla DeLorean]

Posted on July 25, 2017 at 02:46

It is pointer to multiple chars, you can't define it as 'char ch' needs to be 'char *ch'

char *ch

= 'UART test\r\n'; // It is a pointer

HAL_UART_Transmit(&huart1,(uint8_t *)ch, 10, 0xFFFF); // It is a pointer, you don't need the address of the pointer, lose the &

[L C]

Posted on July 25, 2017 at 03:59

Clive One

Thanks for your help. It is work fine.

Clive One & ALL

My target is using UART like a terminal for display(output) & input to STM32.

To refer my provided code, the send out data size is necessary predefined.

HAL_UART_Transmit(&huart1,(uint8_t *)ch,

10

, 0xFFFF)

In application, the message size is not fixed. I think it is simple example only.

If predefined it bigger, it will occupy memory all the time. 

How can I to optimize it?

For receive data, I see some example using time window to wait input data from UART port.

This method need CPU ask & wait input data. It will consume CPU time resource.

If using interrupt method, how can I to receive ALL data/message and NOT a character only?

Finally, shall we use simple transmit function(

HAL_USART_Transmit

) AND interrupt receive function(

HAL_USART_Receive_IT

) together?

Another side I should use 

HAL_USART_TransmitReceive

or 

HAL_USART_TransmitReceive_IT

?

Please let me know your comment.

BR