xr17v258 Exar Corporation, xr17v258 Datasheet - Page 29

• Manufacturer Part Number: xr17v258
• Description: 66mhz Pci Bus Octal Uart With Power Management Support
• Manufacturer: Exar Corporation

xr
REV. 1.0.0
(channel 2),......., 0xF00 (channel 7). This operation is at least 16 times faster than reading the data in 64
separate 8-bit memory reads of RHR register (0x000 for channel 0, 0x200 for channel 1, 0x400 for channel
2,......, 0xE00 for channel 7).
The XR17V258 also provides the same RX FIFO data along with the LSR status information of each byte side-
by-side, at locations 0x180 (channel 0), 0x380 (channel 1), 0x580 (channel 2), ....., 0xF80 (channel 3). The
entire RX data along with the status can be downloaded in a single PCI Burst Read operation of 32 DWORD
reads. The Status and Data bytes must be read in 16 or 32 bits format to maintain data integrity. The following
tables show this clearly.
3.1.2
Data Bit-31
WITH N
Data Bit-31
WITH LSR
Read n+0 to n+3
Read n+4 to n+7
Read n+0 to n+1
Read n+2 to n+3
PCI Bus
R
R
PCI Bus
EAD
EAD
B7 B6 B5 B4 B3 B2 B1 B0
B7 B6 B5 B4 B3 B2 B1 B0
Etc.
Receive Data Byte n+1
RX FIFO,
RX FIFO,
Etc
Receive Data Byte n+3
O
Special Rx FIFO Data Unloading at locations 0x180, 0x380, 0x580, and 0x780
E
E
RRORS
RRORS
Channel 0 to 7 Receive Data with Line Status Register in a 32-bit alignment through the Configuration
Channel 0 to 7 ReceiveData in 32-bit alignment through the Configuration Register Address
Register Address 0x0180, 0x0380, 0x0580, 0x0780, 0x0980, 0x0B80, 0x0D80 and 0x0F80
FIFO Data n+3
FIFO Data n+7
FIFO Data n+1
FIFO Data n+3
B
B
0x0100, 0x0300, 0x0500, 0x0700, 0x0900, 0x0B00, 0x0D00 and 0x0F00
B7 B6 B5 B4 B3 B2 B1 B0
B7 B6 B5 B4 B3 B2 B1 B0
YTE
YTE
66MHZ PCI BUS OCTAL UART WITH POWER MANAGEMENT SUPPORT
Line Status Register n+1
Receive Data Byte n+2
3
3
FIFO Data n+2
FIFO Data n+6
LSR n+1
LSR n+3
B
B
YTE
YTE
29
B7 B6 B5 B4 B3 B2 B1 B0
B7 B6 B5 B4 B3 B2 B1 B0
2
2
Receive Data Byte n+1
Receive Data Byte n+0
FIFO Data n+1
FIFO Data n+5
FIFO Data n+0
FIFO Data n+2
B
B
YTE
YTE
1
1
B7 B6 B5 B4 B3 B2 B1 B0
B7 B6 B5 B4 B3 B2 B1 B0
Receive Data Byte n+0
Line Status Register n+0
FIFO Data n+0
FIFO Data n+4
LSR n+0
LSR n+2
B
B
YTE
YTE
XR17V258
Data Bit-0
PCI Bus
0
0
Data Bit-0
PCI Bus