NEC PD754144 User Manual page 169

CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
<2> To output a leader code with a 9 ms period to output a carrier clock and a 4.5 ms period to output a
low level (Refer to the figure below.)
• Set the higher 4 bits of the timer counter mode register (TM1) to 0110B and select 15.6 ms as the
longest set time.
• Set the lower 4 bits of TM1 to 1100B. Then, select the 8-bit timer counter mode, count operation,
and timer start command.
• The initial set value of the timer counter modulo register (TMOD1) is as follows.
9 ms
– 1 = 147.5 – 1
61 µ s
• The set value for rewriting TMOD1 is as follows.
4.5 ms
– 1 = 73.8 – 1
61 µ s
• Set the higher 4 bits of TC2 to 0000B.
• Set the lower 4 bits of TC2 to 0000B. The carrier clock is output when no return zero data is "1",
and the no return zero data to be output next is cleared to "0".
<Program example>
SEL MB15
MOV XA, #093H
MOV TMOD1, XA
MOV XA, #00000000B
MOV TC2, XA
SET1 NRZ
MOV XA, #01101100B
MOV TM1, XA
EI
EI IET1
; <Subroutine>
MOV XA, #049H
MOV TMOD1, XA
RETI
147 = 93H
73 = 49H
; or CLR1 MBE
; Sets modulo (carrier clock output period)
; Sets no return zero data to "1"
; Sets mode and starts timer
; Enables interrupt
; Enables interrupt of timer counter channel 1
; Rewrites modulo (low-level output period)
9 ms
User's Manual U10676EJ3V0UM
4.5 ms
169