Searching \ for '[PIC]:PISO Register' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/devices.htm?key=pic
Search entire site for: 'PISO Register'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]:PISO Register'
2002\05\22@104459 by Goring, Steve

flavicon
face
Hi All ..

I have an application where I will be using an 872 as a kind of router and
several
f84's which will be picking up the information, doing look-ups and driving
displays.

Before I get hammered over the f84's - I am using these as they are the last
of
my stock, honestly I do use the 628 now. ( Phew ... )

My question is this, the 872 will be getting the information via 232, it
will then decide
which f84 it is bound for, the selected f84 will be notified that there is
information
for it. The 872 will place the byte out in parallel and the f84 will then
clock the byte
in serially and process it.

CAN I use a single common PISO ( 74ls165 ) or do I need one per f84. I had
imagined that when the f84 was notified it had mail !! it wold parallel load
and then
clock in the data, not sure if I can connect together all the clock, pl and
data lines ?

This is a parts reduction exercise.

Thanks in advance


Steve




**********************************************************************
Information in this email is confidential and may be privileged.
It is intended for the addressee only. If you have received it in error,
please notify the sender immediately and delete it from your system.
You should not otherwise copy it, retransmit it or use or disclose its
contents to anyone.
Thank you for your co-operation.
**********************************************************************

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\05\22@111248 by Byron A Jeff

face picon face
On Wed, May 22, 2002 at 03:42:07PM +0100, Goring, Steve wrote:
> Hi All ..
>
> I have an application where I will be using an 872 as a kind of router and
> several
> f84's which will be picking up the information, doing look-ups and driving
> displays.
>
> Before I get hammered over the f84's - I am using these as they are the last
> of
> my stock, honestly I do use the 628 now. ( Phew ... )

I'm guess my posts are having an effect! ;-)

{Quote hidden}

You should use a 74HC165 or 74HCT165 instead to ensure that you get the
correct high voltage margin.

You need 3 different actions for your three lines.

data: All of the 16F84s inputs can be tied to this one pin. There shouldn't
be a fanout problem.

Parallel Load: Have the 872 control it so that when the it notifies the 16F84
the register is already loaded.

clk: wire-or all the 16F84 clocks together. You can do this in software by
controlling the corresponding TRIS pin, or in hardware by using a diode on
the output. Coupled with a pullup resistor, any number of 16F84's can drive
the clock.

You can use an idle timeout on the 872 to figure out when the register has
been cleared. Or if you can to add some hardware you can add a counter that
counts the number fo clocks.

BAJ
{Quote hidden}

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2002\05\22@120301 by Alan B. Pearce

face picon face
> This is a parts reduction exercise.

So why not have the 872 do a software uart to transmit the data ? You can
set the baud rate to something that will not take too much processing time,
but I doubt it will increase the code that very much over what you would
have anyway.

There is no reason why you could not have all the receive uart pins on the
84's connected directly to the single uart transmit pin on the 872.

Equally if you need a return data path, because you will have a software
uart on the 84's to transmit, use a data protocol that requires the 872 to
request info from a specific 84, which then causes that 84 to take its uart
transmit pin out of tri-state, transmit the required message, and then
return to tri-state mode on that pin. You could equally do this by having
the port pin set to 0, and do all the transmitting by manipulating the TRIS
register.

Having written the above, there is no reason why you could not use the SPI
mode to transmit to the 84's anyway. Just treat it as a PISO that is built
into the 872 :))))))) Now how is that for hardware reduction :)))))

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...