Simulating PPI(8255) chip on a 8051 chip

Have anyone idea that how can I simulate signal timing of 8255 chip (PPI) on a 8051 chip?
That means that I want to use a programmed 8051 chip in place of a ppi.

You can program 8051 to act as 8255 PIA ..
To control 8255 you need 11 lines: /RD, /WR/ A0, A1 and D0-D7 ..
All what you have to do is to program 8051 to read from (or to write to) multiplexed address/data bus .. if you know how it works it shouldn't be difficuit ..
Once you have this, take commands used by a microcontroller to controll 8255 and write procedures in 8051 to act identically ..

For example, to set pin PC0 8255 receives a command consisting of address of the controll register followed by direct bit set/clear command ..
Address is locked in the 8255 on falling edge of /WR and command goes into it on the rising edge of /WR .. and that is what 8051 should be "taught" to do ..

You can select Int0 and INt1 as /RD and /WR, any general purpose I/O as A0 and A1, and any available 8-bit port to act as 8-bit multiplexed address/data bus ..

Regards,
IanP

That means that I want to use a programmed 8051 chip in place of a ppi.

Click to expand...

No, you can not do that, 8051 pins is not enough for simulate all 8255 pins!

8255 pin usage :
Port A + Port B + Port C = 24 pin
Data bus (D0..D7) = 8 pin
/RD, /WR, A0, A1, /CS, Reset = 6 pin
Total of 38 pin

8051 has only 32 pins (port 0.. port 3) to simulate all of that!