BM28723AMUV
Description of Function - continued
18.3 BCLK High or Low Speed Detection function
BCLK high or low speed detection function counts the period of BCLK rising edge by using internal clock (12MHz to 25MHz) ,
and if the count value go beyond a constant value, it judge that abnormal speed of clock is occurred such as BCLK speed
become high or low.
When using a BCLK speed detection, speed failure detection can be more correctly performed by making a command set
reflect about an input sampling rate.
When you validate sampling rate setting, be sure to set up the sampling rate inputted with 0x0C [1:0] command. A high
speed and the low speed detection flag can set up validity and the invalidity respectively. If valid flag is detected, output is
muted (immediate mute).
Valid or invalid frequency value setting up by 0x0C[1:0] command.
Default=0x0
Select Address
0x0A[3]
Value
Explanation of Operation
0x0
Valid
0x1
Invalid
Setting of input sampling rate
Default=0x0
Select Address
0x0C[1:0]
Value
0x0
Explanation of Operation
48kHz
44.1kHz
32kHz
0x1
0x2
The setting of constraints of a high speed or a low speed detection condition
Default=0x0
Select Address
Value
Explanation of Operation
0x0A[2]
0x0
±10%
It can check detection result by reading back.
The result judged that is once unusual is not cleared until it transmits a clear command, even if the condition of a clock
returns to normal. It is possible to set the number of judging count of high speed flag detection and low speed flag detection
by the command. If the error more than the predetermined number is detected, the flag (0x0A[1], 0x0B[1]) becomes 0x1.
BCLK high speed flag (Read Only)
Select Address
0x0A[1]
Value
0x0
Explanation of Operation
Normal
High speed detection flag
0x1
BCLK low speed flag (Read Only)
Select Address
Value
0x0
Explanation of Operation
0x0B[1]
Normal
Low speed detection flag
0x1
High speed detection clears register (Write Only)
Select Address
0x0A[0]
Explanation of Operation
If 0x1 writes in, a high speed detection flag will be cleared.
Caution: When using Auto recovery from clock error function (P.62) , the above-mentioned flag is cleared automatically.
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