YMF795 Datasheet, PDF (20/45 Pages) YAMAHA CORPORATION – APL-2 Automobile sound Player-2

YMF795
$39h Clock setting
Default: 0000h
Index b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
$39h
0
0
0
0
00
0
CLKSET
The register is used to set the clock frequency that is input through the CLK_I pin when the setting is made in the
programmable mode. Be sure to complete the setting before its sound generation.
A clock with any frequency can be input during the reset period.
For details of the clock setting, see “Clock Frequency Setting” (page 24).
CLKSET [8:0]
000000000b
000000001b
:
000101111b
000110000b
000110001b
:
111110001b
111110010b
111110011b
:
111111111b
Clock frequency(MHz)
(Preset mode)
Prohibition
:
Prohibition
2.684658000
2.740588375
:
27.797396375
27.853326750
Prohibition
:
Prohibition
The values that can be set to CLKSET are “000000000b”, and “000110000b” to “111110010b.”
When other value is set, the operation is not guaranteed.
A value to set to CLKSET can be found by using the following formula.
CLKSET = Clock frequency [KHz] / 447.443 × 8
For example, when the clock frequency is 3 MHz:
CLKSET = 3000 / 447.443 × 8 is about 54 = 000110110b
And, actual clock frequency to be set is as follows.
Clock frequency [kHz] = 54 × 447.443 / 8 = 3020.24[kHz] = 3.02024[MHz]
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