This is a copy of my code I'm using to transmit to the m5450/51,
(that doesn't seem to work).
See anything glaringly wrong that would make this chip not work properly?

I'm using Bank 1 R0-R4 for the 36 bits that need to be transmitted.


;***************************************************************
; Function: Transmit
;
; Description: Just transmits 36 bits to the m5450/51.
;
; 36 Pins
; r0 r1 r2 r3 r4
; 1111111x|11111111|11xxxxxx|11111111|11xx0000
; 0123456 78901234 56789012 3456
; 12345678 91111111 11222222 22233333 3333
; BITS BITS

; 1-7 rows 1-7
; 9-13 LED1(c1-5) green
; 14-18 LED2(c1-5) green
; 25-29 LED1(c1-5) red
; 30-34 LED2(c1-5) red
;
;***************************************************************

ST_tx:
;***************************************************************
; Microcontroller ports dedicated to ST serial communications
; DATA In
StDA BIT P1.6
; CLOCK
StCL BIT P1.7

CLR A

using 1
; DATA is in BANK 1


;set bit 1 to begin transmission
SETB StDA
lcall SCloop ; blip the clock

txloop:
mov A,r0
lcall xmit

mov A,r1
lcall xmit

mov A,r2
lcall xmit

mov A,r3
lcall xmit

mov A,r4
anl A,#0f0h
lcall xmit

using 0
RET
;
xmit:
CLR C
mov r5,#8 ; counter for bit tx's
XmitLoop:
CLR StDA ;clear data bit
; moves the bit to transmit into the carry bit
RLC A
JNC Xmitc1
SETB StDA
xmitc1:
lcall SCloop
djnz r5,xmitloop ; ? transmitted all 8 bits
xmitexit:
CLR StDA
clr A
RET

SCLoop:
lcall xmitdlay

SETB StCL

lcall xmitdlay
lcall xmitdlay
lcall xmitdlay

CLR StCL

lcall xmitdlay

ret

xmitdlay:
mov R6,25 ;Work out the djnz delay value
txDel2:
mov B,#200
txDel3:
djnz B,txDel3 ; loop delay
djnz R6,txDel2 ; this many times

ret