Problem with DTMF IC (CM8870) interfacing with AT89C51 micro-controller

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Joined May 6, 2016
I am work on Project Home Automation system using DTMF technology ,but i have some problem with interfacing,

my dtmf ic works very well but when i connect the output pin Q0-Q3 with AT89C51 micro-controller (on P1 port)
and after pressing any key on keypad, than DTMF o/p is not goes high (or power consume anywhere) so controller not consider any i/p,
but when i not connect o/p of dtmf with controller than o/p of dtmf is works very well it's goes high (5v) respect with key-pres on keypad.
can any one know about this problem solution than please give me suggestion on this....