Analogue Control Interface

FX839

© 1997 Consumer Microcircuits Limited

12

D/839/4

VARIABLE ATTENUATOR Register (Hex address $D2)

This is a 16-bit register. Byte (1) is sent first. Bits 0 - 5 of the first byte in this register are used to enable and

set the attenuation of the Modulator 1 amplifier and bits 0 - 5 of the second byte in this register are used to

enable and set the attenuation of the Modulator 2 amplifier, according to the tables below:

BYTE 1

BYTE 2

543210

Mod. 1 Attenuation

543210

Mod. 2 Attenuation

0

XXXXX

0

XXXXX

100000

>40dB

100000

>40dB

100001

12.0dB

100001

6.0dB

100010

11.6dB

100010

5.8dB

100011

11.2dB

100011

5.6dB

100100

10.8dB

100100

5.4dB

100101

10.4dB

100101

5.2dB

100110

10.0dB

100110

5.0dB

100111

9.6dB

100111

4.8dB

101000

9.2dB

101000

4.6dB

101001

8.8dB

101001

4.4dB

101010

8.4dB

101010

4.2dB

101011

8.0dB

101011

4.0dB

101100

7.6dB

101100

3.8dB

101101

7.2dB

101101

3.6dB

101110

6.8dB

101110

3.4dB

101111

6.4dB

101111

3.2dB

110000

6.0dB

110000

3.0dB

110001

5.6dB

110001

2.8dB

110010

5.2dB

110010

2.6dB

110011

4.8dB

110011

2.4dB

110100

4.4dB

110100

2.2dB

110101

4.0dB

110101

2.0dB

110110

3.6dB

110110

1.8dB

110111

3.2dB

110111

1.6dB

111000

2.8dB

111000

1.4dB

111001

2.4dB

111001

1.2dB

111010

2.0dB

111010

1.0dB

111011

1.6dB

111011

0.8dB

111100

1.2dB

111100

0.6dB

111101

0.8dB

111101

0.4dB

111110

0.4dB

111110

0.2dB

111111

0dB

111111

0dB

X = don't care

MOD1 ENABLE

(Bit 5, first byte)

When this bit is '1' the MOD1 attenuator is enabled.

When this bit is '0' the MOD1 attenuator is disabled (i.e. powersaved).

MOD2 ENABLE

(Bit 5, second byte)

When this bit is '1' the MOD2 attenuator is enabled.

When this bit is '0' the MOD2 attenuator is disabled (i.e. powersaved).

(Bits 7 and 6, first

and second bytes)

Reserved for future use. These should be set to '0'.