[SOLVED] Is it possible to control a single pin of MC23017?

[jayanth.devarayanadurga]

Is it possible to control a single pin of MC23017? I need to control individual pins without altering the state of other pins.

 

[mvs sarma]

to my limited knowledge, i suppose a human eye can't see, but there would be a blink as, we have to transmit all 8 bits again changing only the bit under concern. Perhaps it is like refreshing with needed bit altered.

 

[paulfjujo]

hello,


it seems only byte can be transmit to the output, but through an internal latch of MCP23017.
So to modify only one bit,you can read the latch, do an OR or AND function with the bit you want to change
and send back (write) the ORed or ANDed value to the device without affect the other PIN

 

[jayanth.devarayanadurga]

Thank you paulfjujo. That solved the problem. I am now able to set or clear individual pins.

 

[spudboy488]

Or keep a shadow variable/register in the uP and modify it using AND and OR operations as paulfjujo described. Then you just need to write the register. It should be faster as well.