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Connect PIC to a PPI ??

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ambition

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If I want to conncet microcontroller like (PIC 16F84 )
to more than one IO device , for example three : touch screen, keypad, and anther device
can I just connect the PIC to PPI and deal with them through this

will that work? or I need to think about it in more advanced way ?

Please help
 

It's ok but not the best way !
 

    A

    ambition

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As a port expander you can use parallel data transmission, and it is quite fast if you use microcontrollers which use multiplexed address/data bus such as 8051 family (with built-in control line such as RD, WR, and so on..) - 8255 the best example ..
For PIC, however, I would rather consider I2C bus and port expanders tailored for this configuration. Have a look at ICs, such as: PCF8575, MAX7311 or MAX7314, to name just a few. They will add 8, 16 or more .. digital I/Os to your microcontroller ..
Regards,
IanP
 

    A

    ambition

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thanks , you helped me a lot ^_^
 

For a 16F84, which does not have any sort of dedicated interface (SPI or I2C), I would simply use a bunch of shift registers (74HC595) and shift the data into them. That will take 3 I/O's on the PIC (clock, data, load). For digital inputs, again you can use shift registers, such as the good old 4021. That takes 3 lines too (clock, data, load). But clock and data can be shared between the input shift register and the output one. So by using only 4 I/O lines on the PIC you can expand the I/O's to as many as you want.
Actually, you should limit that to about 32 inputs 32 outputs. Otherwise, it will take forever to shift any data in / out.:D
 

Hello vvv

No problem. if the guy is using a high level language, especially those that enable you to use commande that are not hardware dependent, such as SHOUT in PICBasic Pro
 

I agree with VVV and Metal...

Also check out the Micrel MIC5841A 8-bit serial to parallel "driver" IC... It's a cascadable 8-bit serial-to-parallel driver capable of driving relays or other loads... Much like the 74HC595, it uses three control pins (data, clock, and strobe/latch)...

Regards, Mike
 

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