Digital Audio Interfacing and Networking 147539.5.4 Simple Instruction Set
The simple instruction set is sent as a 2 byte signal with
a minimum of 1 byte break between commands sent.
Each byte is sent MSB first.
39.5.5 Direct Commands
Table 39-2 shows the direct commands.
Figure 39-12. AES42 data format for the simple instruction set. Time flows from right to left in this diagram. Note that the
MSB of each byte is sent first. After each 2 byte instruction there is a required break of 1 byte’s worth of time. Addressing
for the simple instruction set is contained in bits 0–2 of the address byte.
Required breakMixing consoleDirect command enable bits0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7Data AddressLSB MSB LSB MSBDigital microphoneTable 39-2. Direct CommandsDirect Command Address Byte
Bits 0–2 Direct Command Enable bits
Bit 0 1 2
State 0 0 0 Identifies this command using the
Extended Command set. See Extended
Instruction Commands below.
1 0 0 Direct Command 1 (low-cut filter, direc-
tivity control, preattenuation).
0 1 0 Direct Command 2 (mute, limiter, signal
gain).
0 0 1 Direct Command 3 (synchronization).
All other possible states of bits 0–2 are reserved and are
not to be used unless defined by the AES in the future.
Bits 3–7 Optional synchronization control word extension.
Bit 3 4 5 6 7
State 0 0 0 0 0 Default if synchronization control word
extension not used.
x x x x x If the optional synchronization control
word extension is used, bit 7 will be the
MSB and bit 3 the LSB of the extension.
Direct Command 1 Data Byte
Bits 0–1 Low-Cut Filter
Bit 0 1
State 0 0 No filter, default.
1 0 Low-cut filter 1 (manufacturer defined).
0 1 Low-cut filter 2 (manufacturer defined).
1 1 Low-cut filter 3 (manufacturer defined).
Bits 2–5 Directivity
Bit 2 3 4 5State 0 0 0 0 Manufacturer defined directivity, default.
1 0 0 0 Omnidirectional.
0 1 0 0 Increasing directivities
0 0 1 0 through this state.
1 0 1 0 Subcardioid.
0 1 1 0 Increasing directivities
1 1 1 0 Through this state.
0 0 0 1 Cardioid.
1 0 0 1 Increasing directivity.
0 1 0 1 Supercardioid.
1 1 0 1 Hypercardioid.
0 0 1 1 Increasing directivities
0 1 1 1 through this state.
1 1 1 1 Figure of eight.
Bits 6–7 Preattenuation
Bit 6 7
State 0 0 No attenuation, default.
1 0 Attenuation 1 (minimum).
0 1 Attenuation 2.
1 1 Attenuation 1 (maximum).
Direct Command 2 Data Byte
Bit 0 Mute
0 Mute off, default.
1 Mute on.
Bit 1 Limiter
0 Limiter disabled, default.
1 Limiter enabled.
Bits 2–7 Gain
Bit 2 3 4 5 6 7
State 0 0 0 0 0 0 0 dB gain, default.
0 0 0 0 0 1 +1 dB gain.
x x x x x x Increasing 1 dB per count.
1 1 1 1 1 1 +63 dB gain.
Direct Command 3 Data Byte
Bits 0–7 SynchronizationTable 39-2. Direct Commands (Continued)