D21G Interruption in only one channel (Ex. CH1)

Hi, indeed the interrupt is triggered by any channel change, unless you mask the channels you do not want to connect to the interrupt. You can do this with the current Indio library as follows:

  Indio.digitalMode(3, INPUT_MASKED); 

This is a new feature, we have not documented it yet but you can check the library source code if you need details.

Alternatively, you could set a flag in the ISR to indicate that the interrupt is triggered, and then in the main loop, when the flag is detected, check if the channel you want to detect (eg. CH1) has changed state or not. Do not call the Indio library within the ISR, that will not work. Obviously you can also poll the CH1 every loop to check its status without using the interrupt, but the above solution with an interrupt will be slightly faster as you won't need to poll CH1 every loop, only when the flag is set.

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Tom

Tom

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Answered on 8/23/18, 12:28 AM

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This seems to work well for blocking interrupts from other inputs triggering the interrupt; but when we configure a channel as an output and issue a output write on another channel that seems to interrupt it, does it make sense to add OUTPUT_MASKED if that would work and makes sense? or any suggestions on how to block the interrupt from firing at all except on one channel input and ignoring all other channels regardless of them beingconfigure as inputs or outputs... Thanks, Josh

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Josh Nijenhuis

on 1/26/19, 4:26 AM

Just reading through the PCA9555 data sheet and at point 8.4.1 it does say that an output shouldn't cause an interrupt. Waiting your response, hopefully there is an explanation... Thanks, Josh

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Josh Nijenhuis

on 1/26/19, 4:44 AM

hi Josh, please note the current INDIO uses PCAL9555A, and the output indeed does not cause an interrupt, please refer to my email

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Tom

on 1/28/19, 1:54 AM

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Thanks Tom,

I have tested and it is working.
Just to be sure, for the outputs, is it necessary to configure something?

Indio.digitalMode(1, INPUT);           
  Indio.digitalMode(2, INPUT_MASKED);     
  Indio.digitalMode(3, INPUT_MASKED);     
  Indio.digitalMode(4, INPUT_MASKED);    
  Indio.digitalMode(5, INPUT_MASKED);     
  Indio.digitalMode(6, INPUT_MASKED);    

  Indio.digitalMode(7, OUTPUT);          
  Indio.digitalWrite(7, LOW);             
  Indio.digitalMode(8, OUTPUT);         
  Indio.digitalWrite(8, LOW);            

A pin configured as an output can trigger the interruption?
I have modified the status and it is working fine, but I prefer to check any posibility.

Another point, is it still necesary to include the following lines when the interruptions are used in D21G?

 Wire.begin();
  Wire.beginTransmission(0x21);
  Wire.write(0x4A);
  Wire.write(0x00);                 //  low byte
  Wire.endTransmission();
  Wire.beginTransmission(0x21);
  Wire.write(0x4B);
  Wire.write(0x00);                 //  low byte
  Wire.endTransmission();           // END OF EXTRA

Best regards.

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Antonio_Per

Antonio_Per

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Answered on 8/23/18, 11:11 AM

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