Help with serial data communications

Im starting to work on a new project... I need help with some tricks with serial communications.... I want to use a pic16c54c for a processor... What I want to do is read the status of mutiple inputs 10-12 lines. More than what a PIC has.. I was thinking of using a couple of shift registers but I dont have the know how with routines.... Any help out there? thank you!

try simulation in proteus. u can even simulate the PC serial port. this will be help full in interfacing the ckt with system

Hello Chevy man,
My first question is why you are using a 16C54, which is a one time programable PIC. There are a lot of newer flash devices, which often cost less than the old OTPs.
That said, you want to use a parallel in, serial out shift register, like the 74hc165, or 74hc597. Basically, you first latch the data on the shift register (if it has a latch,) then you shift the data in the register into your pic with the serial clock pin. Each These can be cascaded, which adds an extra pin to the circuit for each chip. It will take only three pins of your pic for the first shift reg, and one extra pin for each additional register, so for 16 bit input, four pins of your pic. The data sheet for the shift register you choose will give you the timing requirements for the chip.
By reading the data sheet, you will get the idea of which pic pins to toggle, at which times, to shift the data from your shift reg into your pic.
Hope this is what you were looking for, but feel free to ask more questions.
Best wishes,
Robert

Another option is port expanders ..

16bit I/O:
https://www.e-lab.de/downloads/DOCs/PCA9555.pdf
28-bit I/O:
**broken link removed**

These IC are ideal if more inputs are required and will generate an interrupt on input level transition ..

Regards,
IanP