CP3BT23_14 Datasheet, PDF (172/324 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

CP3BT23
SNOSCX3A – JULY 2013 – REVISED JANUARY 2014
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DMA Support
If DMA support is enabled for a receive slot n (RXDSA0 = 1), all data received in this slot is only
transferred from the ARSR into the corresponding DMA receive register (ARDRn). A DMA request is
asserted when the ARDRn register is full.
If DMA is enabled for a transmit slot n (TXDSAn = 1), all data to be transmitted in slot n are read from the
corresponding DMA transmit register (ATDRn). A DMA request is asserted to the DMA controller when the
ATDRn register is empty.
Figure 19-4 illustrates the data flow for IRQ and DMA support in network mode, using four slots per frame
and DMA support enabled for slots 0 and 1 in receive and transmit direction.
SRD
ARSR
DMA Slot
Assignment
S ^{lot 1 data}
Sol _{t 2 and 3data}
ARDR 0
ARDR 1
DMA
Request 1
DMA
Request 3
ARDR 2
ARDR 3
RX
IRQ
FIFO
STD
ATSR
DMA Slot
Assignment
Slot ^{1 dat a}
Slot _{2 and 3}
d _ata
ATDR 0
ATDR 1
DMA
Request 0
DMA
Request 2
ATDR 2
ATDR 3
TX
FIFO
IRQ
DS056
Figure 19-4. IRQ/DMA Support in Network Mode
If the interface operates in synchronous mode, the receiver uses the transmit bit clock (SCK) and transmit
frame sync signal (SFS). This allows the pins used for the receive bit clock (SRCLK) and receive frame
sync (SRFS) to be used as additional frame sync signals in network mode. The extra frame sync signals
are useful when the audio interface communicates to more than one codec, because codecs typically start
transmission immediately after the frame sync pulse. The SRCLK pin is driven with a frame sync pulse at
the beginning of the second slot (slot 1), and the SRFS pin is driven with a frame sync pulse at the
beginning of slot 2. shows a frame timing diagram for this configuration, using the additional frame sync
signals on SRCLK and SRFS to address up to three devices.
SFS
SRCLK
(auxiliary
frame sync)
SRFS
(auxiliary
frame sync)
STD/SRD
Data from/to Data from/to Data from/to
Codec 1
Codec 2
Codec 3
Slot 0
Slot 1
Slot 2
Slot 3
Frame
DS057
Figure 19-5. Accessing Three Devices in Network Mode
172 Advanced Audio Interface
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