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What to do when more ports are needed

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osspi

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What to do when more port are needed

Am using pic16f877a which my pi are 44 and I wan to display message on my dot led up to 70 leds. Plz what can I do because I need more port so that it can display
 

Re: what to do when more port are needed

Use shift register to make more output for example : 74HC595 .
 

Re: pic 18f26k40 bootloader

I ask dor additional port to run my led and I was told to use 74ch595 but I try it it not working plz can you explain how to use it and how to call the port d because am using my port b for the 595
 

Re: what to do when more port are needed

Hi,

The HC595, its function and code has been discussed many times here in this forum.
It's really nothing new.

Do a forum search on your own.

Klaus
 

Re: what to do when more port are needed

It works according to serial to parallel data with time clock ,

Give 70 data to 74hc595 serial Pin from micro controller you need to connect cascaded Nine 74Hc595 IC to take the date to parallel

To get logic I am posting a link Here where is multiple input making into 3 wire .The reverse action will do 74HC595.
**broken link removed**
 
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Re: what to do when more port are needed

I would personally prefer to use a parallel port expansion, such as the 74HCT373/4 or something like that. This is because the expansion of pins with shift register in series, in case of some error (although unlikely if all components are on the same board) will only propagate the error forward. In other hand, with I/O expansion in parallel, at each new refresh the value will be updated, superposing any error.
 
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