BU9414FV Datasheet, PDF (25/61 Pages) Rohm – 32bit Audio DSP

BU9414FV
Technical Note
4-7. MIDDLE
MIDDLE of TONE Control uses Peaking filter.
The setting is converted, in the IC, into digital filter’s coefficients （b0, b1, b2, a1, a2）by selecting the F，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.
○MIDDLE Control
Selection of smooth transition function
Default = 0
Select Address
&h44 [ 6 ]
Value
0
1
Operational explanation
Using MIDDLE smooth transition function
Not MIDDLE using smooth transition function
Selection of smooth transition time
Default = 0
Select Address
&h44 [ 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 &h44[0] command, to the coefficient RAM
for smooth transition, the alteration of MIDDLE’s coefficients is completed by using this command.
Default = 0
Select Address
&h4C [ 1 ]
Value
0
1
Operational explanation
MIDDLE smooth transition stop
MIDDLE smooth transition start
What is necessary is the time of waiting, which is more than the time selected by the setting of MIDDLE smooth transition
time, from the time the MIDDLE smooth transition start （&h4C[1] = “1”） is executed until the following command is sent.
Please make sure to perform the MIDDLE smooth transition stop（&h4C[1] = “0”） after the smooth transition is completed.
Setting of the Start of transmitting to coefficient RAM
In the case of using the smooth transition, it is transmitted to the coefficient RAM for smooth transition. In the case of not
using of the smooth transition, it is transmitted to the direct coefficient RAM.
Default = 0
Select Address
&h44 [ 0 ]
Value
0
1
Operational explanation
MIDDLE coefficient transmission stop
MIDDLE coefficient transmission sart
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2012.03 - Rev.A