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problem with st92f120

peppecaselli
Associate II
Posted on August 30, 2005 at 04:54

problem with st92f120

5 REPLIES 5
peppecaselli
Associate II
Posted on May 17, 2011 at 11:37

I have a problem with two identical circuits that use micro st92f120. The systems work with an external quartz to 4 MHz and INTCLK 20MHz. The first one works correctly. The other system goes reset every three second ones. What can be? I have changed also micro of according to system and the quartz. I do not use wachtdog hw/sw and interrupt. Help me!!!

sergio2
Associate II
Posted on May 17, 2011 at 11:37

you should Connect the HW0SW1 pin to Vdd through a 1K pullup

peppecaselli
Associate II
Posted on May 17, 2011 at 11:37

Thanks Sergio!!! You have reason because it is the only one pin that it had the various voltage in the two circuits. Now they work. But the pins that I do not use, as an example AD\ DS\ RW where I must connect them? I have not connected these pins. I must connect them to Vdd or not?

sergio2
Associate II
Posted on May 17, 2011 at 11:37

It is always a good practice not leave floating pins

It is convenient to connect, the unused pins to Vdd or Vss,

This will also improve,l the total power consumption of the chip

peppecaselli
Associate II
Posted on May 17, 2011 at 11:37

Thanks for your answers and the aid.

Peppe