NEC PD754144 - Manual (Page 172)

CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
172 User’s Manual U10676EJ3V0UM
BR SEND_1_F ; If data is 0, proceeds to transmission processing of next
data with PTO2 pin outputting low level
CALL !SEND_D_1
BR SEND_1_F
SEND_END : ; Completes transmission of 16 bits of data
;
GET_DATA: ; Searches data of BSB indicated by @L. Sets value to H
register
SKT BSB0.@L
MOV A, #0
MOV A, #1
MOV H, A
RET
SEND_D_0 : ; Processing to set carrier output of data 0 and 1 and first low
level output
LOOP_1ST : SKTCLR IRQT1
BR LOOP_1ST ; Waits for carrier output
RET ; Starts output of first low level
SEND_D_1 :
CLR1 NRZB ; Sets second low level output if data is 1
LOOP_2ND : SKTCLR IRQT1
BR LOOP_2ND ; Waits for first low level output
; Starts second low level output
CLR1 NRZB ; Sets third low level output
LOOP_3RD : SKTCLR IRQT1
BR LOOP_3RD ; Waits for second low level output
; Starts third low level output
RET