NEC 78K0 User Manual page 252

8-bit timer Hn
count clock
8-bit timer counter
Hn count value
CMPn0
CMPn1
TMHEn
INTTMHn
Carrier clock
8-bit timer 5n
count clock
TM5n count value
CR5n
TCE5n
INTTM5n
INTTM5Hn
NRZBn
NRZn
Carrier clock
TOHn
<1> When TMHE1 = 0 and TCE51 = 0, 8-bit timer counter H1 operation is stopped.
<2> When TMHE1 = 1 is set, 8-bit timer counter H1 starts a count operation. At that time, the carrier clock is held
at the inactive level.
<3> When the count value of 8-bit timer counter H1 matches the CMP01 register value, the first INTTMH1 signal
is generated, the carrier clock signal is inverted, and the compare register to be compared with 8-bit timer
counter H1 is switched from the CMP01 register to the CMP11 register. 8-bit timer counter H1 is cleared to
00H.
<4> When the count value of 8-bit timer counter H1 matches the CMP11 register value, the INTTMH1 signal is
generated, the carrier clock signal is inverted, and the compare register to be compared with 8-bit timer
counter H1 is switched from the CMP11 register to the CMP01 register. 8-bit timer counter H1 is cleared to
00H. By performing procedures <3> and <4> repeatedly, a carrier clock with duty fixed to 50% is generated.
<5> When the INTTM51 signal is generated, it is synchronized with 8-bit timer H1 count clock and output as the
INTTM5H1 signal.
<6> The INTTM5H1 signal becomes the data transfer signal for the NRZB1 bit, and the NRZB1 bit value is
transferred to the NRZ1 bit.
<7> When NRZ1 = 0 is set, the TOH1 output becomes low level.
252
CHAPTER 9 8-BIT TIMERS H0 AND H1
Figure 9-15. Carrier Generator Mode Operation Timing (1/3)
(a) Operation when CMP01 = N, CMP11 = N
00H N 00H
<3>
<1> <2>
00H 01H L 00H 01H
<5>
0 1
0
User's Manual U15947EJ2V0UD
N 00H N 00H N 00H
N
N
<4>
L 00H 01H L 00H 01H
L
*
0 1
<6>
1 0
<7>
N 00H N
L 00H 01H
0
1 0