Product specifications

VT8237R Data Sheet
Revision 2.06 December 15, 2004 -147- Device 17 Function 6 Modem Controller Registers
I/O Base 0 Regs – Modem Scatter / Gather DMA
Modem SGD Read Channel Registers
I/O Offset 40 – Modem SGD Read Channel Status.....RWC
7 SGD Active ..........................................................RO
0 SGD has completed or been terminated.default
1 SGD Active
6 SGD Paused ..........................................................RO
0 SGD not paused .....................................default
1 SGD Paused
5-4 Reserved ........................................ always reads 0
3 SGD Trigger Queued...........................................RO
This bit reports whether the trigger used to restart the
SGD operation is queued (I/O Offset 41[1] = 1 while
the SGD engine is running).
0 SGD trigger not queued .........................default
1 SGD trigger queued (when SGD reaches EOL,
it will restart).
2 SGD Stop Interrupt Status..............................RWC
1 SGD finished the index equal to the stop index
set in 4B-48[31-24].
1 SGD EOL (End Of Link) ................................RWC
1 Block is the last of the link. May be used by
software as a signal to generate an interrupt
request if I/O Offset 41[1] = 1.
0 SGD Flag ......................................................RWC
1 Block complete. May be used by software as a
signal to generate an interrupt request if I/O
Offset 41[0] = 1.
I/O Offset 41 – Modem SGD Read Channel Control.....RW
7 SGD Start ............................ WO (always reads 0)
0 No effect
1 Start SGD read channel operation
6 SGD Terminate ...................... WO (always reads 0)
0 No effect
1 Terminate SGD read channel operation
5-4 Test (Do Not Program)...................... always write 0
3 SGD Pause .........................................................RW
0 Release SGD read channel pause and resume
the transfer from the paused line
1 Pause SGD read channel operation (SGD read
channel pointer stays at the current address)
2-1 Reserved ........................................ always reads 0
0 Modem SGD Read Reset
0 Normal Operation ..................................default
1 Reset Modem SGD read channel operation
I/O Offset 42 – Modem SGD Read Channel Type......... RW
7 Auto-Start SGD at EOL
0 Stop at EOL........................................... default
1 Auto restart at EOL
6-4 Reserved ........................................always reads 0
3-2 Interrupt Select
This bit determines the timing of interrupt generation
when bit-1 or bit-0 of this register are equal to 1.
00 Interrupt at PCI Read of Last Line ........ default
01 Interrupt at Last Sample Sent
10 Interrupt at Less Than One Line to Send
11 -reserved-
1 Interrupt on EOL @ End of Block
0 Disable................................................... default
1 Enable
0 Interrupt on FLAG @ End-of-Blk
0 Disable................................................... default
1 Enable
I/O Offset 47-44 – Modem SGD R Ch Table Ptr Base .. RW
31-0 SGD Table Pointer Base Address (even addr).... W
Current Pointer Address ....................................... R
I/O Offset 4F-4C – Modem SGD R Ch Current Count.. RO
31-24 Current Modem SGD Read Channel Index
This field reports the index the SGD engine is
currently processing.
23-0 Current Modem SGD Read Channel Count
This field reports the count remaining in the current
entry being processed. For example, if 10 bytes of a
30-byte count have been transferred, this field would
read 20 to indicate 20 bytes remaining.
Modem SGD Table Format
63
62 61 60-56 55-32 31-0
EOL FLAG STOP -reserved- Base Base
Count Address
[23:0] [31:0]