Cirrus-logic CS44600 Manuel d'utilisateur télécharger pdf (Page 56)

56 DS633F1

CS44600

1. Convert the decimal integer to binary. This is MSTR_IVOL[7:0].

2. Select the bit representation of the desired 0.25 fractional increment. This is MSTR_FVOL[1:0].

3. Concatenate MSTR_IVOL[7:0]: MSTR_FVOL[1:0] to form a 10-bit binary value.

4. Perform a 2’s complement conversion on all 10 bits.

The upper 8 bits are now the new MSTR_FVOL[7:0] and the two lower bits are MSTR_FVOL[1:0].

To convert from a 2’s complement integer:fraction value to a negative decimal, do the following:

1. Concatenate MSTR_IVOL[7:0]: MSTR_FVOL[1:0] to form a 10-bit binary value.

2. Perform a 2’s complement conversion on all 10 bits.

3. Convert the 10-bit binary number to a decimal value.

4. Divide the decimal value by 4.

MSTR_IVOL[7:0] MSTR_FVOL(1:0) Volume Setting

0001 1000 00 +24.00 dB

0001 0111 10 +23.50 dB

0000 0001 11 +1.75 dB

0000 0001 00 +1.00 dB

0000 0000 01 +0.25 dB

0000 0000 00 0 dB

1111 1111 10 -0.50 dB

1111 1111 00 -1.00 dB

1111 1110 11 -1.25 dB

1111 1101 10 -2.50 dB

1000 0010 00 -126.00 dB

1000 0001 11 -126.25 dB

1000 0001 00 -127.00 dB

Table 7. Master Fractional Volume Settings

1 2 ... 51 52 53 54 55 56 57 58 59 60 61 ... 75 76

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Cirrus-logic CS44600 Manuel d'utilisateur Page 56