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I/O extenders for 8051-compatible microcontrollers

 
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NikiZ
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PostPosted: Sat May 22, 2004 6:45 am    Post subject: I/O extenders for 8051-compatible microcontrollers Reply with quote

I am woorking on a project, based on 8051 compatible microcontrollers and i need many input/output buses.
Can someone tell me what IC should i use?
I have heard of the Intel I/O extender 8255 and for many other, using the I2C protocol. Where can i find information which solution is better ?
I will be very grateful if someone helps me with ideas or information on the question.
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toltec
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PostPosted: Sat May 22, 2004 6:51 am    Post subject: Reply with quote

8255 is rather old, but it is cheap and has 3 x 8 I/O ports.
There is a lot written about this IC.
An I2C extender is PCF8574,PCF8574A ( the second one has a different address ).
They have 3 hardware-programmable bits, which allows each I2C bus to be connected
to 8 pieces of each (and they are 8 - bit).
The convenience is that the communication occurs only on 2 buses
( SDA, SCL), but you have to be familiar with the protocol.
I have personally used them and have written assembler code for 8051 for them/
Another cheap option is to use CMOS shift registers 4094 (for output)
and 4021 for input.
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