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20.2.2 Frequency Data Register
The frequency data register stores the reload value for the frequency counter. The stored value represents
the frequency of the sound (or the tone signal from the toggle flip-flop). The register value is reloaded into
the counter at every transition of the toggle signal.
The following figure shows the relationship between the tone signal and the register value.
n Frequency Data Register
Frequency data register
Address: 00005C
H
Read/write →
Initial value →
Figure 20.2 shows the relationship between a tone signal and a register value.
Tone signal
Fig. 20.2 Relationship between Tone Signal and Register Value
It should be noted that modifications of the register value during operation may alter the duty cycle of 50%
depending on the timing of the modification.
SOUND GENERATOR
7
6
5
D7
D6
D5
(R/W)
(R/W)
(R/W)
(X)
(X)
(X)
One Tone Cycle
(Register value + 1) ×
(Register value + 1) ×
One PWM cycle
20-7
4
3
2
D4
D3
D2
(R/W)
(R/W)
(R/W)
(X)
(X)
(X)
One PWM cycle
← Bit No.
1
0
D1
D0
SGFR
(R/W)
(R/W)
(X)
(X)
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