Press and release button

[NASI]

Hello,

I need help to implement a function for some buttons, that every time a button is pressed a CAN message will be sent and when the button is released the CAN message will be sent again.

It has to send a CAN message for falling and rising edge (doesn't matter the time between falling and rising time), and I don't want to configure GPIO as GPIO_EXTI.

Thank you.

[Peter BENSCH]

Well, if you do not want to configure GPIO as GPIO_EXTI, i.e. you do not want to work with interrupt, you have to work in polling mode:

• declare pin status as a variable and set it to the start state (e.g. not pressed = 0),
• query the pin status in a simple while loop (e.g. via HAL_GPIO_ReadPin) and compare it with the variable mentioned before,
• if changed, store the status in the variable and send the CAN message

Does it answer your question?

Regards

/Peter

[NASI]

Thank you @Peter BENSCH​ 

Would you please complete the following code based on your suggestion.

BT1 = HAL_GPIO_ReadPin(GPIO_Port, GPIO_Pin);

if(BT1 == 0 && ...)

{

//Button is pressed

Send CAN; //send CAN only once

}

if(BT1 == 1 && ...)

{

Button is released

Send CAN; //send CAN only once

}

Thank you

[Peter BENSCH · Accepted solution]

What I mean is something like the following code (GPIO-PinState can also be replaced by uint_32):

GPIO_PinState ButtonStateCurrent;
GPIO_PinState ButtonStateLast = GPIO_PIN_RESET;
 
while (1)
{
  ButtonStateCurrent = HAL_GPIO_ReadPin(GPIO_Port, GPIO_Pin);
  if (ButtonStateCurrent != ButtonStateLast)
  {
      Send_CAN_Msg();
      ButtonStateLast = ButtonStateCurrent;
  }
  // any delay
}

BTW: the code will be better readable if you use the button Code Snippet = </> below.

[NASI]

Thank you so much @Peter BENSCH​ 

[NASI]

Would you please look at this question and if you could answer it, @Peter BENSCH​ 

 https://community.st.com/s/question/0D53W00001aIZKRSA4/both-can-bus-interrupt

Thank you.

[Peter BENSCH]

If this question cannot be answered by anyone here in the community, you should perhaps make a personal enquiry in our Online Support so that you can be helped directly.

Regards

/Peter