MT9196 Mitel Semiconductor, MT9196 Datasheet - Page 24

• Manufacturer Part Number: MT9196
• Description: Integrated Digital Phone Circuit (IDPC)
• Manufacturer: Mitel Semiconductor

MT9196
Note: Bits marked "-" are reserved bits and should be written with logic "0".
7-150
Anti-Howl Control Register
High Tone Coefficient Register
High Threshold Register
Low Threshold Register
The frequency of the high group tone is programmed by writing an 8-bit hexadecimal coefficient at this address according to the
following equation:
Where the hexadecimal COEFF is converted into a decimal integer between 0 and 255. Frequency resolution is 7.8125Hz in the range
0 to 1992 Hz.
Enable
MS1, MS0
Pad2-0
THh6-0
THl6-0
Enable
Seven bits encoding the magnitude of the high threshold level. Encoding is in PCM sign-magnitude excluding the sign bit.
Seven bits encoding the magnitude of the low threshold level. Encoding is in PCM sign-magnitude excluding the sign bit.
THh0 - THh3 encode the step number while THh4 - THh6 encode the chord number. The default setting of 'X011 0000'
encodes chord 3 step 0. The difference between the high and low thresholds defines the hysteresis for anti-howling.
THl0 - THl3 encode the step number while THl4 - THl6 encode the chord number. The default setting of 'X001 0100'
encodes chord 1 step 4. The difference between the high and low thresholds defines the hysteresis for anti-howling.
H7
When high, the anti-howling circuit is enabled. When low, the anti-howling circuit is disabled.
Encode the operational mode of the anti-howling circuit as follows. Details of each mode are found in the functional
MS1
Three bits encoding the attenuation depth which will be switched into the transmit or receive paths by the anti-howling
Pad2
description of the anti-howling circuit.
circuit. Note that 12 dB is the default value.
0
0
1
1
-
-
7
7
7
7
0
0
0
0
1
1
1
1
THh6
THI6
MS0
H6
-
6
6
0
1
0
1
6
6
Pad1
0
0
1
1
0
0
1
1
THh5
THI5
MS1
H5
Operational Mode
Transmit Noise Squelch
Receive Noise Squelch
Anti-howling for group listening
Tx/Rx Switched Loss
5
5
5
5
Pad0
0
1
0
1
0
1
0
1
THh4
THI4
MS0
H4
4
4
4
4
Frequency (in Hz) = 7.8125 x COEFF
THh3
THI3
H3
3
3
3
3
-
Attenuation (dB)
Pad2
THh2
THI2
H2
0
3
6
9
12
15
18
21
2
2
2
2
Pad1
THh1
THI1
H1
1
1
1
1
ADDRESSES 1Fh to 3Fh are RESERVED
ADDRESS = 1Ch WRITE/READ VERIFY
ADDRESS = 1Bh WRITE/READ VERIFY
ADDRESS = 1Dh WRITE/READ VERIFY
ADDRESS = 1Eh WRITE/READ VERIFY
Pad0
THh0
THI0
H0
0
0
0
0
Preliminary Information
Power Reset Value
Power Reset Value
Power Reset Value
Power Reset Value
0X10 X100
X011 0000
X001 0100
0000 0000