I haven't looked closely at the specific data sheet., but the general
pattern for 3-wire devices is this:

Pull CS slow. This tells the device to start expecting the data bits.

Clock in the data bits, however many there are.

Bring CS high. This tells the device that all the data has been entered and
it can act on it.


So... to answer your questions:

> Bob
>     Ive been trying to figure out how to do this with the maz7219. Do I
need
> to keep cs low at all times or does it toggle back and forth every 16
bits.

Toggle it back and forth

> also what i need know  is i have set up two registier to do a 16 bit rrf
to
> stuff info in and pull it out for display.

This chip expects the hi bits first, so you have to use RLF instead of RRF.
See below

>Do i set the cs low right after i
> initialize porta and b ?

as described above, no.

Code, slightly modified, as per Bob Blick (warning untested!)

; DATA on PORTB,7
; CLOCK on PORTB,6
; CS on PORTB,5

; data to send in srlo,srhi
; uses temporary register "count"
; does not trash srlo or srhi

    bcf        PORTB,5    ; activate CS
    movlw    .17             ; 1 per bit, plus one extra
    movwf    count
    goto    ROTATE
LOOP:
    bsf        PORTB,6    ; toggle clock
    nop
    bcf        PORTB,6
ROTATE:
    rlf          srlo,F            ; rotate 16-bit value, hi bit to carry
    rlf          srhi,F

    skpnc                         ; copy carry to data pin
    bsf         PORTB,7
    skpc
    bcf        PORTB,7

    decfsz    count
    goto       LOOP

    bsf          PORTB,5    ; deactivate CS

    return




Bob Ammerman
RAm Systems

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.