Calling MCP23016 pins

Newzed

I have an MCP23016 with a lot of lines working.· I need to monotor the state of just of of the pins.· Can I write

if GP0.7·= 128 then do something?

12 of the pins on the chip could be in any state but I am only concerned about the state of GP0.7

Sid

Chris Savage

Sid, if you're monitoring one bit, then it would be either a 1 or 0...

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Chris Savage

Knight Designs
324 West Main Street
P.O. Box 97
Montour Falls, NY 14865
(607) 535-6777

Business Page:·· http://www.knightdesigns.com
Personal Page:··· http://www.lightlink.com/dream/chris
Designs Page:··· http://www.lightlink.com/dream/designs
·

Jon Williams

You need to read the whole port, then check the bit in question. Something like this:

I2CIN SDA, slaveAddr, GP0, [noparse][[/noparse]temp]
IF (temp.BIT7) THEN
  ' do something
ENDIF

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Jon Williams
Applications Engineer, Parallax
Dallas Office

Newzed

I took the easy way out, Jon.· I wrote:

if GP0>=128 then dosomething.·

This statement is true only of GP0.7 is
high.· If it is NOT true, then GP0.7 must be low.

Sid

Jon Williams

You're right.· On the other hand, you could write "better" (my opinion -- please hold your flames) code by doing things like this:

flags   VAR  Byte
frGate  VAR  flags.BIT7
 
IsOpen  CON  1
 
...
 
  IF (frGate = IsOpen) THEN
    ' deal with open front gate
  ENDIF
 

To many this seems like a lot of work, but after 20 years of programming I can assure you that it saves the programmer time, and is immensely helpful when that same programmer wants to share his/her code with others.· It's also helpful when you change a circuit design as a couple changes in your definitions section is easier than hunting through a long listing for "magic numbers."

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Jon Williams
Applications Engineer, Parallax
Dallas Office