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i can't make work pcf8574a interrupt

 
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jd_batista



Joined: 15 May 2008
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i can't make work pcf8574a interrupt
PostPosted: Thu May 15, 2008 9:46 am     Reply with quote
I have a trouble with this device. I have switches in all input pins. Initially INT are low but when i turn off any switch and the input go low; INT doesn't do anything. Please every info about how to read pcf8574a with a 16f877a. I really appreciate it.
thank you
PCM programmer



Joined: 06 Sep 2003
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PostPosted: Thu May 15, 2008 12:07 pm     Reply with quote
The PCF8574A data sheet says this:
Quote:
Open-Drain Interrupt Output


Do you have a pull-up resistor on the \INT pin ?
You need one. Add a 4.7K pull-up to that pin.
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