Datasheet
Figure 48-10 illustrates the synchronous data formats for MediaLB. For stereo 24-bit data, two physical channels
(PCn) are needed per frame where the data is packed and left-justified in the two quadlets. In the 32-bit sequential
format, data fills the entire quadlet with the internal data format determined by the system implementor
.
Figure 48-10. MediaLB Synchronous Data Structure
MLBS
Tx
Device:
SyncData
PCn
(1 quadlet = 1 physical
channel)
Rx
Device:
ReceiverReady
Tx
Device:
SyncData
PCn+m
(1 quadlet = 1 physical
channel)
Rx
Device:
ReceiverReady
MLBD
16-bit
Mono
MLBD
16-bit
Left
16-bit
Right
MLBD
24-bit
Mono
MLBD
24-bit
Left
24-bit
Right
24-bit
Right
MLBD
MSB
LSB
32-bit
Sequential
MSB
MSB
MSB
MSB
MSB
MSB
LSB
LSB
LSB
LSB LSB
LSB
The synchronous flow for a Tx Device is illustrated in Figure 48-1
1. The data transfer blocks (slanted rectangle
shapes) occur only during a physical channel (PCn) associated with the logical channel defined by a single
ChannelAddress. The flow diagram contains only one state: Transmit. Once a channel has been initialized, the
Transmit state is entered. If a Tx Device has no data to transmit, it must still send the SyncData command and set the
actual data to a safe value, such as all zeros. To stop sending synchronous data, the logical channel must be
eliminated (ChannelAddress removed from MediaLB).
The synchronous flow for an Rx Device is illustrated in Figure 48-12. The flow diagram also contains only one state,
Continue, where the Rx Device waits for data from the Tx Device. No command other than SyncData is expected or
allowed. When the SyncData command is detected, the corresponding data quadlet sent with the command is
received and stored in the Rx buffer. Any command received, other than SyncData, is a ProtocolError and should be
reported to the application. Furthermore, the data quadlet received with the invalid command is discarded and
replaced with a safe value.
Since the default bus state is ReceiverReady, the Rx Device must not drive the MLBS line with RxStatus since
ReceiverReady is the only allowable response for synchronous data. The system stops the transfer of synchronous
data by eliminating the logical channel (ChannelAddress) from the bus. If an Rx Device does not receive its
ChannelAddress in the frame, it should assume that the channel is not setup yet, or that the logical channel has been
eliminated and should respond accordingly (for example, mute outputs).
Figure 48-11. Synchronous Data Tx Device Protocol
Init
State =
Transmit
yes
Data ready to send
no
?
Send
Command SyncData
Send
Data
sync
data
Receive
RxStatus
Send
Command SyncData
Send
Data
0x00000000
Receive
RxStatus
SAM E70/S70/V70/V71 Family
Media Local Bus (MLB)
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1344