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Help choosing a PIC
Posted: Sat Mar 31, 2012 7:42 pm
by Bobw
I am not new to PIC's but far from an expert..
Requirements:
Operate from 5 volts
6 inputs for switches. ( I know they can be multiplexed onto one pin)
2 inputs for a quadrature encoder.
4 outputs for relays and led.
Outputs for a glcd.
1k of EPROM would be more than enough.
I have used16f1827 pics before but need a few more I/O pins.
Ideas?
Bob
Re: Help choosing a PIC
Posted: Sat Mar 31, 2012 9:00 pm
by medelec35
Re: Help choosing a PIC
Posted: Sat Mar 31, 2012 10:46 pm
by Bobw
Hey Martin,
While I didn't find that thread on my own. I have been to the Microchip site and have been looking at their chip selector guide.
Trying to really plan this one out, not so trial and error like last time.
Only have the PIC and display left to find.
Thanks
Bob
Re: Help choosing a PIC
Posted: Sat Mar 31, 2012 11:08 pm
by medelec35
I would be inclined to go for the 18F series since they can run at faster speeds (48MHz) than 16F series.
That would be better for updating Glcd.
What about something like 18F4455?
If its good enough for the MIAC
Martin
Re: Help choosing a PIC
Posted: Sun Apr 01, 2012 1:58 am
by Bobw
I was looking at that one.
Lost all my notes in a computer crash, so really starting from scratch.
I thought there were a couple of chips out there now that had built in support for quadrature encoders (QID?)
Just know having extra I/O pins is a good thing.
Re: Help choosing a PIC
Posted: Sun Apr 01, 2012 3:21 pm
by Bobw
OK,
I am down to the 18F4431 that has the QEI support built in.
And the 18F4455 that does not.
The 4455 is faster and has more memory.
If I hook up the quadrature encoder on the interrupt on change I/O pins what would I loose/gain with the QEI support?
Re: Help choosing a PIC
Posted: Mon Apr 02, 2012 9:33 am
by Benj
Hello Bob,
I'm afraid I have never used the QEI peripheral so I can't really tell you the upside of using this. The downside is you would probably have to access this using C code.
The upside of using a IOC or timer based encoder is that Flowcode v5 supports this directly and it is very reliable as long as you have the timer set fast enough or the IOC setup correctly on the encoder pins.
Re: Help choosing a PIC
Posted: Mon Apr 02, 2012 2:44 pm
by Bobw
Thanks for the info everyone.
I have decided to use the 18F4455
It may be a bit overkill for my needs but have already added 2 more I/O functions to my list.
I also see it has 3 interrupt pins, and on paper is plenty fast.
Best part is that FC5 supports it.
Bob