MB90590 Datasheet, PDF (356/502 Pages) Fujitsu Component Limited. – 16-BIT MICROCONTROLLER HARDWARE MANUAL

CHAPTER 21 SOUND GENERATOR
21.2.2 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.
s Frequency Data Register
Frequency Data register
Address: 001946H
7
6
5
4
3
2
1
0
D7
D6
D5
D4
D3
D2
D1
D0
Bit number
SGFR
Read/write
Initial value
(R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W) (R/W)
(X)
(X)
(X)
(X)
(X)
(X)
(X)
(X)
Figure 21.2-1 shows the relationship between a tone signal and a register value.
Figure 21.2-1 Relationship between Tone Signal and Register Value
One Tone Cycle
Tone signal
(register value+1) x (register value+1) x
One PWM cycle
One PWM cycle
It should be noted that modifications of the register value while operation may alter the duty
cycle of 50% depending on the timing of the modification.
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