Circuit to emulate 8255 mode 0

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SISWANTO

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8255 circuit

Dear everyone,
I want to develop I/O board like 8255, but I try to avoid 8255,
because 8255 have a problem with EMI (electrical Magnetic Interference).
Anyone can advice me, what ICs or device that I can use?



Siswanto 8O :?:
 

No problem EMI with 8255 Chip.

Please insert 0.1 uF capasitor shunt between VCC and GND in 8255 chip.
 

I have been using this IC for years and never have had such problems.
Depending on what is connected to I/Os I always use small serial resistors (10Ohm), 4.7k-10k pull-ups and 5.1V zener diodes between pins and GND.
As mentioned above decoupling caps are a must...

However, if you don't want to use the 8255 then as outputs you can employ octal latch 74373 and as inputs octal buffer 74244 or octal transceiver 74245...
 

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