
PSB 7230
Firmware Features
Semiconductor Group
127
Data Sheet 1998-07-01
P(1-0)
Part number of the data in this packet. Allows the natural period of the
data to be 10 to 40 ms. For G.723 takes on the values 0, 1 or 2
corresponding to the first, second or third part of a 30 ms data packet.
Is always 0 for the other modes.
Note: To avoid the updating of these bits by the user in each frame
when operating in G.723 mode, the JADE AN auto-increments
the P-bits. Nevertheless, the user has to take care that G.723
encoder and decoder are running synchronously, i.e. the part
number of the received and transmitted packet in one 10 ms
frame must be identical for control and status. For that, after
switching to G.723 mode the user has first to wait for valid
packets (i.e. wait for I = 0) and second to read the P(1-0) status
bits to synchronize the data stream transmitted to the JADE AN
correspondingly, i.e. if the user receives a status value of 2 from
the JADE AN, it also has to transmit a part 2 packet in the current
10 ms frame.
The P(1-0) control block bits sent by a user are ignored by the JADE AN
when operating in G.723 mode. This is to avoid collisions between the
host and the auto-increment mechanism in the JADE AN.
00
First part of compressed audio packet (G.723: part 1/3)
01
Second part of compressed audio packet (G.723: part 2/3)
10
Third part of compressed audio packet (G.723: part 3/3)
11
Fourth part of compressed audio packet (G.723: reserved)
Loopback modes (see
Figure 44
), used for testing the audio
subsystem.
000
No loopback (default)
001
Send received compressed data back to the user as encode
data
010
Encode the decoded user data
011
Reserved
100
Reserved
101
Decode the encoded audio input data
110
Send the digital ADC output to the DAC input
111
Reserved
L(2-0)