[SOLVED] Can I write a 8 bit or 16 bit Data to the outport of the STM32 directly

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thannara123

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I am using STM32F103 ,CUBE IDE with HAL library , I am trying to write the outport as giving a 4 bit value to the entire port (16bit ) By using a shift bit operator . Can I directly apply that data to the port as follows. GPIO_PORTA |= 0x0ff; Like wise Or how to write it
 

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Hello!

Not sure of what you want to know, I don't understand thee 4 bits and shift question. Are you asking if you can write a 16-bit number directly at the output? If you are looking for this, then you have this instruction for instance if you want to write 0xABCD to the output.

GPIOA->ODR = 0xABCD;

ODR stands for Output Data Register.
Similarily, you have an IDR for input. But before that, be sure that the direction is properly configured.

NB: writing to GPIO_PORTA will (probably) not do anything good. It's the base structure to the port registers, so you have to name which field of PORTA you want to change.

Dora.


 
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Thanks

(I am learning STM32 based programming with HAL )
By using HAL Library ,
How to put data as follows
GPIOA->ODR = 0xABCD;
what is the procedure
writing 16 bit data to the whole port expect individual bit ?
--- Updated ---

@doraemon Thanks​

It workded
 
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Hi,

HAL is a library. Each HAL command will be processed by a function. Each function may consist of a bunch of machine instructions.

There are instructions to SET dedicated bits (OR style)
There are instructions to CLEAR dedicated bits (AND style)

Using both these instructions in a function you are able to "write" any combination to the output:
Each bit in a 16 bit word can be
* unchanged
* HIGH
* LOW

*****
You may do the same functionality with different instructions. Like:
* read port pins into a variable
* perform OR on the variable
* perform AND on the variable
* write variable to the port

***
Maybe there are single instructions that perform both masking and updating in one. For this you need to read the instruction set.

***
You should provide an example of what exactly you want to achieve

Klaus
 

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thannara123 said:
By using HAL Library ,
How to put data as follows
GPIOA->ODR = 0xABCD;
Click to expand...
There's no HAL_GPIO function to manipulate multiple pins at once. Instead you'll use GPIO register read and write instructions, as suggested.

You don't necessarily manually code the and/or operations to write part of a register. After defining a respective structure, the compiler can take care of it.
 

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Then GPIOA->ODR = 0xABCD; is it wrong idea ,May i need to write each bitfield one by one ?
--- Updated ---

I can touch the whole port as said @doraemon .whch can be make flexxible to me to write code (I dont know it is good )
I feel it is good to touch the port to direct .please comment my queries





 
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I still didn't hear clearly what you want to achieve.
thannara123 said:
Then GPIOA->ODR = 0xABCD; is it wrong idea ,May i need to write each bitfield one by one ?
Click to expand...
For writing 16 bit of data to GPIOA->ODR at once, the instruction is correct, because GPIOx_ODR register uses only 16 bit and requires the upper word to be set to 0. But you have been asking how to write 4/8/16 bit data, so it's not the general solution.
 

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Sir I am here writing 4 bit data to the 16bit port by the above said way ,
Is it correct ,its for sending 4 bita data to the lcd for 4 bit mode
is it correct .
 

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The command sequence is only setting but not resetting GPIO bits, thus not achieving what you want.

You can either define respective bit fields or use and/or to mask previous register value.
Code: 
 GPIO->ODR = (GPIO->ODR & 0x0fff) | (cmd & 0xf000);
 

    thannara123

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After writing to the PORT and strobe ,may i need it to reset sir can you elaborate .
May I get the code snipet full for the function like you said above ?


or as follows
C: 
void LCD_cmd(__uint16_t cmd)
{       HAL_GPIO_WritePin(GPIOB,GPIO_PIN_11, GPIO_PIN_RESET);    
        cmd = (cmd << 8) ;
        GPIOB->ODR =  0xf000 & cmd;
        LCD_Strobe();
        GPIOB->ODR = (GPIOB->ODR & 0x0fff) | (cmd & 0xf000);
         HAL_GPIO_WritePin(GPIOB,GPIO_PIN_11, GPIO_PIN_RESET);
        cmd = (cmd << 4) ;
        GPIOB->ODR =  0xf000 & cmd;
        LCD_Strobe();
        GPIOB->ODR = (GPIOB->ODR & 0x0fff) | (cmd & 0xf000);

}

}



sir Please correct if wrong
 
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Don't know how pin11 comes into play. It's not used in your previous code.
Code: 
void LCD_cmd(__uint16_t cmd)
{ 
        cmd = (cmd << 8) ;
        GPIOB->ODR = (GPIOB->ODR & 0x0fff) | (cmd & 0xf000);
        LCD_Strobe();
        cmd = (cmd << 4) ;
        GPIOB->ODR = (GPIOB->ODR & 0x0fff) | (cmd & 0xf000);
        LCD_Strobe();
}
 
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I just noticed by looking at your parallel same topic thread that pin 11 is not register select, it's enable pin. Really bad to post code without specifying the hardware.
 

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