cx82100 Conexant Systems, Inc., cx82100 Datasheet - Page 112

• Manufacturer Part Number: cx82100
• Description: Home Network Processor Hnp
• Manufacturer: Conexant Systems, Inc.

7.7.4
Figure 7-6. TMAC DMA Operation for Channel {x} = 1 or 3
7-14
Sequence of Transmitter DMA Operation
Conexant Proprietary and Confidential Information
TMAC DMA operation is illustrated in Figure 7-6.
TMAC starts the DMA on channel {x} by issuing
the DMA_S AVE command to DM AC. DMAC
saves PTR 1 to PRT2 and CNT1 to CNT2.
no
CX82100 Home Network Processor Data Sheet
TMAC issues DMA_XNXT command
to DMA C to receive the TDES and
the 1st 4 bytes of the data.
Host programes the base
pointer DMAC_{x}_PTR1 and
the length DMAC_{x}_CNT 1 for
the 1st fragment of the frame
Host sets the E_NA_STRT bit in
register E_NA_{x} to cause the
TMA C to start the transmission
Host assembles the frame to
be transmitted in linked list
structure and writes the T DES
TM AC issues DMA_XNX T
commands to fill up the F IFO
and starts transmitting nibbles.
T MAC issues DMA_XN XT
command to DMAC to skip
the TSTAT field.
TMAC issues
DMA_XSAVE to request
DMAC to write the TS TAT
to host memory
TMAC issues DMA_IN TR
to DMAC to signal the
end of a frame.
TMAC continues to
transmit nibbles in the
FIFO until completion.
TDES.RDY bit O N?
Last double word
received?
yes
yes
no
TM AC updates the E_S_TU bit in register
E_Stat_1 (or E_Stat_2) to interrupt the
host, providing the bit E_IE_TU is set in
register E_IE_1 (or E_IE _2)
Host reads the bit
TSTAT.TDN to determine
the transmission status.
TMAC Transmission
stopped.
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