NEC 78K0 Series User Manual page 286

8-bit timer H1
count clock
8-bit timer counter
H1 count value
CMP01
CMP11
TMHE1
INTTMH1
Carrier clock
<1> When TMHE1 = 1 is set, the 8-bit timer H1 starts a count operation. At that time, the carrier clock remains
default.
<2> When the count value of the 8-bit timer counter H1 matches the value of the CMP01 register, the INTTMH1
signal is output, the carrier signal is inverted, and the timer counter is cleared to 00H. At the same time, the
compare register whose value is to be compared with that of the 8-bit timer counter H1 is changed from the
CMP01 register to the CMP11 register.
<3> The CMP11 register is asynchronous to the count clock, and its value can be changed while the 8-bit timer
H1 is operating. The new value (L) to which the value of the register is to be changed is latched. When the
count value of the 8-bit timer counter H1 matches the value (M) of the CMP11 register before the change, the
CMP11 register is changed (<3>').
However, it takes three count clocks or more since the value of the CMP11 register has been changed until
the value is transferred to the register. Even if a match signal is generated before the duration of three count
clocks elapses, the new value is not transferred to the register.
<4> When the count value of 8-bit timer counter H1 matches the value (M) of the CMP1 register before the
change, the INTTMH1 signal is output, the carrier signal is inverted, and the timer counter is cleared to 00H.
At the same time, the compare register whose value is to be compared with that of the 8-bit timer counter H1
is changed from the CMP11 register to the CMP01 register.
<5> The timing at which the count value of the 8-bit timer counter H1 and the CMP11 register value match again
is indicated by the value after the change (L).
286
CHAPTER 9 8-BIT TIMERS H0 AND H1
Figure 9-15. Carrier Generator Mode Operation Timing (3/3)
(c) Operation when CMP11 is changed
00H 01H N 00H 01H
<3>
M
<2>
<1>
Preliminary User's Manual U17260EJ3V1UD
00H N
M
N
<3>'
L
M (L)
<4>
00H 01H L 00H
<5>