NEC PD78F9488 - Manual (Page 119)

CHAPTER 6 16-BIT TIMER 20
User’s Manual U15331EJ4V1UD
119
<Countermeasure B> When rewriting using 16-bit access
<1> Disable interrupts (TMMK20 = 1) and inversion control of timer output (TOC20 = 0).
<2> Rewrite CR20 (16 bits).
<3> Wait for one cycle or more of the count clock.
<4> Clear the interrupt request flag (TMIF20).
<5> Enable timer interrupts/timer output inversion
<Program example B> (count clock = 32/f
X
, CPU clock = f
X
)
TM20_VCT: SET1 TMMK20
; Disable timer interrupts
CLR1 TMC20.3
; Disable timer output inversion
MOVW A, #xxyyH
; Set the rewrite value of CR20
MOVW CR20, AX
; Rewrite CR20
NOP
NOP
:
; 16 NOP instructions (wait for 32/f
X
) Note
NOP
NOP
CLR1 TMIF20 ; Clear the interrupt request flag
CLR1 TMMK20
; Enable timer interrupts
SET1 TMC20.3
; Enable timer output inversion
Note Clear the interrupt request flag (TMIF20) after waiting for one cycle or more of the count clock from the
instruction that rewrites CR20 (MOVW CR20, AX).