PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 71

• Manufacturer Part Number: PSB7238
• Description: Joint Audio Decoder-Encoder - Multimode
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

MDR
MER
MDA
MEA
MAB
responds to this inactivity via the idle (1) condition of the MR output bit.
Monitor Packet Transfer
The message transfer starts when the transmitter transmits the value of the first byte of
the monitor data channel and sets the MX bit to its active state (0). The MX bit remains
active until the receiver acknowledges the data or the transmitter software aborts the
transmission. The receiver recognizes the change of the MX bit to the active state and
latches the contents of the monitor data channel. Since the monitor channel address is
always transmitted as the first byte of a message, all receiving devices compare (per
hardware or software) the first value with their own address. If a device recognizes its
address it acknowledges the data by changing its MR bit to the active state (0).
The transmitter recognizes this change and can now transmit the next byte of the
message. This is done by transmitting the value in the monitor data channel and setting
the MX bit to the inactive, idle (1) state for one frame and then changing it back to the
active (0) state. The receiver recognizes the transition of MX from the inactive to the
active state and latches the contents of the monitor data channel.
The receiver acknowledges the data transfer by setting the MR bit to the
inactive (1) state for one frame and then back to the active (0) state. This procedure is
repeated until all the data is transferred. Once the receiver has acknowledged the last
value the transmitter switches its MX bit and the monitor channel into the idle (1) state.
The receiver recognizes this idle state after it has received two consecutive frames with
an idle MX bit and will then set its own MR bit in the idle (1) state.
The transmitter recognizes the change of the MR bit and indicates the idle condition after
the second frame. If the receiver wants to abort a transmission, then it will set its MR bit
into an idle (1) condition. The transmitter recognizes the abort condition after the second
frame with an idle MR bit and switches its MX bit and the monitor data channel to idle.
The monitor channel status is reported to the software via four bits in the monitor channel
status register:
Inactivity
The transmitter indicates its inactivity with the idle state of the MX bit (1) and by
transmitting the value FF
Semiconductor Group
Monitor channel Data Received.
Monitor channel End of Reception.
Monitor channel Data Acknowledged.
Monitor End of Acknowledgement.
Monitor channel Abort.
H
(or high impedance) in the monitor data channel. The receiver
71
Data Sheet 1998-07-01
Functional Blocks
PSB 7238