I just wrote my first code and it was for a MM5451!  The most important
thing is to go to National Semiconductor and get the data sheet.  The
chip waits for a start bit, then 35 data bits (34 for MM5450).  Each
data bit will turn an output on or off, depending on if it was high or
low.  An important thing to remember is it only works with common anode
displays, because when the outputs are activated, they sink current.
Current limiting resistors aren't needed because the chip limits the
current, depending on the resistor you use between pins 19 and 20. The
data bits are latched from a low to high transition.  One approach to
displaying charcters is to create a lookup table and then rotate the
bits out to the MM5451.  You have to map out your seven segment display
to match up with your lookup table.  If anyone wants to see my code I'll
send it to you.  It was written to use with a 2 lane car race (cub
scouts pinewood derby) and displays the time results to 100uS resolution
(5 digits x.xxxx).   Good Luck.

Alessandro Zummo wrote:

>  Please help me!
>
>  i've been in trouble while implementing the pic
>  code for the MM5450.. if any1 has some code,
>  please let me know!
>
> Thanks in advance,
>
>    - *Alex* -
>
>       (azummo@ita.flashnet.it)