Where to reset GPIO in console app on close?

Targets Raspberry Pi
1

Hello all,

Just implemented the GPIO functionality. Nice. Very nice! My problem/question is, where is the code put to turn off outputs before the console app quits? I put the following code in the App.Stop event but it does not appear to work - the LED does not turn off.

#If TargetLinux And TargetARM Then
  GPIO.DigitalWrite( k_DTR_LEDPin, GPIO.Off )
  GPIO.DigitalWrite( k_Relay1_Pin, GPIO.Off )  //Set low
  GPIO.DigitalWrite( k_Relay2_Pin, GPIO.Off )  //Set low
#EndIf

Probably important to know is that the app is being “killed” using the Task Manager. Maybe I have the code in the wrong place? But, in addition to having it in the Stop event, I also have it in the serial error event. This code checks to see if the port is still open, if not it turns off the LED.

#If TargetLinux And TargetARM Then
  If Me.ComPortOpened = False Then 
    GPIO.DigitalWrite( k_DTR_LEDPin, GPIO.Off )
  End If
#Endif

Can anyone point me in the correct direction?

Thanks,
Tim

2

Console apps do not have a Stop event. Perhaps you mean a Service app? If so, Service apps are for Windows Services and the Stop event is only called when the Service is stopped (or the computer shuts down).

A console app quits when you reach the end of its Run event. So that would be the place to call a method that does your cleanup. If you are “killing” the app, the OS terminates it immediately so you don’t have control over what code it runs.

3

Thanks for your response Paul.
It is a Service/Daemonized app.
What is the best way to stop a service app, or daemonized app? I had not thought of this - only the opposite, keeping it running!

Thanks,
TIm

4

First, as this is a Raspberry Pi app, there is no need to make it a ServiceApplication as those are for MS Windows. Just make it a ConsoleApplication.

Unfortunately it doesn’t look like there is a good way for a Linux app to catch a termination signal. There are some suggestions in this thread:

https://forum.xojo.com/7860-linux-web-app-how-to-catch-the-kill-signal/0

Or you could build your own mechanism in for your app to listen or look for something that tells it should quit. I suppose maybe a special file with a “QUITME” value in it that your app checks for might work? Or maybe it listens on an IPC socket for a message?

5

Thanks Paul.
I am going to add a push switch connected to the GPIO for shutdown. That works when physically on-site, but not when away. Is it possible that a “helper app” be used to send the app a signal to shutdown? I would assume so - even writing to a text file that the main app reads periodically.

Also, although I am running this on a Pi right now, I am targeting Linux in general since this will eventually be used in other SBC’s and possibly desktop Linux instances.

Thank you again for your reply and continued support!

Tim