Microchip PIC Forum: [piclist] Re: address decode on serial

Tuesday, December 4, 2007

[piclist] Re: address decode on serial

I read about the 9th bit address.....

How do I get the pc to generate it? Im using QBASIC on the pc and
not sure how to create a extra bit there.

Randy

-- In piclist@yahoogroups.com, "Dennis Clark" <dlc@...> wrote:
>
> You don't need to do that with the newer PICs. Read up on "9th bit
> addressing" for the PIC. In this mode the 9th bit is set and the
USART
> recognizes this as an address. Your code then needs only to look
for this
> bit set to pay attention to a byte as an address.
>
> DLC
>
> > Hello all:
> >
> > I have a desire for a project to use a PC as a master, poll
various
> > pics on a rs485 network, using a very simple polling idea and
have
> > the pics respond with their status as well as take data from the
pic
> > if desired.
> >
> > Im working on this in small parts and my first thoughts on
overall
> > programming is this to get the pic to respond to its address:
> >
> > pic watches the data stream for a "sync byte" such as "89"
> > if "89" appears then check the next byte for its address such
as "02"
> > if "02" is its address then respond with its status
> >
> > I tried this before without using the sync byte and the pic
> > responded to any bit sequence that appeared and matched 4 bits.
By
> > using the sync byte, will this help with the false responses? my
> > first attempt was using a addres of "2" and any bit opattern that
> > matched "0010" falsed a response.
> >
> > Serial speed is not set, I tested at 9600.....
> > PIC is 16F627/16F628
> >
> > Im a NOVICE to programming and trying to learn as I go here.
> >
> > All help appreciated!
> >
> > Randy
> > kk4ej
> >
> >
> >
> >
> > to unsubscribe, go to http://www.yahoogroups.com and follow the
> > instructions
> > Yahoo! Groups Links
> >
> >
> >
> >
>
>
> --
> Dennis Clark
> TTT Enterprises
>