[Diy_efi] Continuing the chip switcher "problem"
WSCowell at aol.com
WSCowell at aol.com
Thu Feb 17 08:07:55 GMT 2005
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Hi Marcello,
Way to go! To answer your questions:
1. Correct. No pullups needed from output of 373 to the memory.
2. No series resistors needed between PIC outputs and 373 inputs. BUT I
would use pullups on the PIC outputs, because otherwise they will be in an
indeterminate state until your PIC software asserts itself and configures the
port concerned.
3. Don't forget to tie the INPUTS of all UNUSED devices in the 374 either
high or low - it doesn't matter which. You can leave the outputs
unconnected. You can connect pins like "Output enable" on the 374 directly to Vss or
Vcc without difficulty.
We are all waiting with bated breath to see if you are successful - but I
know where my money is!
Will Cowell
G0OPL
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<DIV>Hi Marcello,</DIV>
<DIV> </DIV>
<DIV>Way to go! To answer your questions:</DIV>
<DIV> </DIV>
<DIV>1. Correct. No pullups needed from output=20=
of=20
373 to the memory.</DIV>
<DIV> </DIV>
<DIV>2. No series resistors needed between PIC output=
s=20
and 373 inputs. BUT I would use pullups on the PIC outputs, because=20
otherwise they will be in an indeterminate state until your PIC software ass=
erts=20
itself and configures the port concerned.</DIV>
<DIV> </DIV>
<DIV>3. Don't forget to tie the INPUTS of all UNUSED=20
devices in the 374 either high or low - it doesn't matter which. You c=
an=20
leave the outputs unconnected. You can connect pins like "Output enabl=
e"=20
on the 374 directly to Vss or Vcc without difficulty.</DIV>
<DIV> </DIV>
<DIV>We are all waiting with bated breath to see if you are successful - but=
I=20
know where my money is!</DIV>
<DIV> </DIV>
<DIV>Will Cowell</DIV>
<DIV>G0OPL</DIV>
<DIV> </DIV></FONT></BODY></HTML>
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