XR17V252_08 Datasheet, PDF (27/69 Pages) Exar Corporation – 66 MHZ PCI BUS DUAL UART WITH POWER MANAGEMENT SUPPORT

XR17V252
REV. 1.0.2
66 MHZ PCI BUS DUAL UART WITH POWER MANAGEMENT SUPPORT
3.1.3 Tx FIFO Data Loading at locations 0x100 (channel 0) and 0x300 (channel 1)
The TX FIFO data (up to the maximum 64 bytes) can be loaded in a single burst 32-bit write operation
(maximum 16 DWORD writes) at memory locations 0x100 (channel 0) and 0x300 (channel 1).
WRITE TX FIFO
Write n+0 to n+3
Write n+4 to n+7
Etc.
BYTE 3
FIFO Data n+3
FIFO Data n+7
BYTE 2
FIFO Data n+2
FIFO Data n+6
BYTE 1
FIFO Data n+1
FIFO Data n+5
BYTE 0
FIFO Data n+0
FIFO Data n+4
Channel 0 to 1 Transmit Data in 32-bit alignment through the Configuration Register Address
0x0100 and 0x0300
Transmit Data Byte n+3
Transmit Data Byte n+2
Transmit Data Byte n+1
Transmit Data Byte n+0
B7 B6 B5 B4 B3 B2 B1 B0 B7 B6 B5 B4 B3 B2 B1 B0 B7 B6 B5 B4 B3 B2 B1 B0 B7 B6 B5 B4 B3 B2 B1 B0
PCI Bus
Data Bit-31
PCI Bus
Data Bit-0
3.2 FIFO DATA LOADING AND UNLOADING THROUGH THE UART CHANNEL REGISTERS, THR
AND RHR IN 8-BIT FORMAT
The THR and RHR register address for channel 0 to channel 1 is shown in Table 11 below. The THR and RHR
for each channel 0 tand 1 are located sequentially at address 0x0000 and 0x0200. Transmit data byte is
loaded to the THR when writing to that address and receive data is unloaded from the RHR register when
reading that address. Both THR and RHR registers are 16C550 compatible in 8-bit format, so each bus
operation can only write or read in bytes.
TABLE 11: TRANSMIT AND RECEIVE DATA REGISTER IN BYTE FORMAT, 16C550 COMPATIBLE
THR and RHR Address Locations For CH0 to CH1 (16C550 Compatible)
CH0 0x000 Write THR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
CH0 0x000 Read RHR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
CH1 0x200 Write THR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
CH1 0x200 Read RHR Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
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