Re: Controlling PCF8583 clock chip with a PIC
From: Jeroen (jayjay.1974_at_xs4all.nl)
Date: Sat, 4 Dec 2004 02:00:58 +0100
"John Gruenenfelder" <firstname.lastname@example.org> wrote in message
> I have a board set up with a PIC16F877 microcontroller and on the I2C bus
> I have a Phillips PCF8583 clock/alarm chip.
> I am attempting to use the alarm function of this chip and thus far am
> having almost no luck getting it to work. I know the I2C bus is good
> because I have several other devices on it plus the clock function of this
> chip is working fine.
> Specifically, no matter what type of alarm I instruct the chip to enable
> (i.e. daily, weekly, etc.) none of them seem to function. I can test this
> by checking the interrupt output pin of the chip with a scope. The
> interrupt generation is enabled, but nothing shows on the pin.
> I realize this is rather general. My hope is that somebody else has used
> this chip and may be able to help me with my problem. If, by any remote
> chance, you have, please contact me or post a followup.
The interrupt output seems to be a open drain output... So it will only
supply a path to ground when an interrupt is active, or high impedance when
not; in other words, you will see nothing on your scope... Add a pull up
resistor to VCC.
Hope this helps,