NEC 78K0 Series User Manual page 285

Figure 9-15. Carrier Generator Mode Operation Timing (2/3)
8-bit timer H1
count clock
8-bit timer counter
H1 count value
CMP01
CMP11
TMHE1
INTTMH1
Carrier clock
8-bit timer 51
count clock
TM51 count value
CR51
TCE51
INTTM51
INTTM5H1
NRZB1
NRZ1
Carrier clock
TOH1
<1> When TMHE1 = 0 and TCE51 = 0, the 8-bit timer counter H1 operation is stopped.
<2> When TMHE1 = 1 is set, the 8-bit timer counter H1 starts a count operation. At that time, the carrier clock
remains default.
<3> When the count value of the 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 the 8-
bit timer counter H1 is switched from the CMP01 register to the CMP11 register. The 8-bit timer counter H1
is cleared to 00H.
<4> When the count value of the 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 the 8-bit timer
counter H1 is switched from the CMP11 register to the CMP01 register. The 8-bit timer counter H1 is cleared
to 00H. By performing procedures <3> and <4> repeatedly, a carrier clock with duty fixed to other than 50%
is generated.
<5> When the INTTM51 signal is generated, it is synchronized with the 8-bit timer H1 count clock and is output as
the INTTM5H1 signal.
<6> A carrier signal is output at the first rising edge of the carrier clock if NRZ1 is set to 1.
<7> When NRZ1 = 0, the TOH1 output is held at the high level and is not changed to low level while the carrier
clock is high level (from <6> and <7>, the high-level width of the carrier clock waveform is guaranteed).
CHAPTER 9 8-BIT TIMERS H0 AND H1
(b) Operation when CMP01 = N, CMP11 = M
00H N 00H 01H M 00H
<3>
<1><2>
00H 01H K 00H 01H
K
<5>
0 1
0 1
<6>
Preliminary User's Manual U17260EJ3V1UD
N 00H 01H M 00H
N
M
<4>
L 00H 01H M 00H 01H
L M
0 1
0
<7>
N 00H
N 00H 01H
N
0
1 0
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