BU9409FV_12 Datasheet, PDF (21/58 Pages) Rohm – 32bit Audio DSP

BU9409FV
Technical Note
4-5. BASS
BASS of TONE Control can use Peaking filter or Low-shelf filter.
The setting is converted, in the IC, into digital filter’s coefficients （b0, b1, b2, a1, a2）by selecting the F₀，Q and Gain, and
transmitted to coefficient RAM. The switching shock noise at the time of alteration of setting can be prevented by the smooth
transition function.
○BASS Control
Selection of filter types
Default = 0
Select Address
&h40 [ 7 ]
Value
0
1
Peaking filter
Low-shelf filter
Operational explanation
Selection of smooth transition function
Default = 0
Select Address
&h40 [ 6 ]
Value
0
1
Operational explanation
Using BASS smooth transition function
Not BASS using smooth transition function
Selection of smooth transition time
Default = 0
Select Address
&h40 [ 5:4 ]
Value
0
1
2
3
21.4ms
10.7ms
5.4ms
2.7ms
Operational explanation
Setting of smooth transition start
In the case of using the smooth transition function, after being transmitted, by the &h40[0] command, to the coefficient RAM
for smooth transition, the alteration of BASS’s coefficients is completed by using this command.
Default = 0
Select Address
&h4C [ 0 ]
Value
0
1
Operational explanation
BASS smooth transition stop
BASS smooth transition start
What is necessary is the time of waiting, which is more than the time selected by the setting of Bass smooth transition time,
from the time the BASS smooth transition start （&h4C[0] = “1”） is executed until the following command is sent. Please
make sure to perform the Bass smooth transition stop（&h4C[0] = “0”） after the smooth transition is completed.
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
21/54
2012.03 - Rev.A