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XR17C158
xr
5V PCI BUS OCTAL UART
REV. 1.4.3
26
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 7 is shown in Table 8 below. The THR and RHR
for each channel 0 to 7 are located sequentially at address 0x0000, 0x0200, 0x0400, 0x0600, 0x0800,
0x0A000, 0x0C00 and 0x0E00. 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 8: TRANSMIT AND RECEIVE DATA REGISTER IN BYTE FORMAT, 16C550 COMPATIBLE
PCI Bus
Data Bit-31
B7 B6 B5 B4 B3 B2 B1 B0
Transmit Data Byte n+3
Transmit Data Byte n+2
Transmit Data Byte n+1
Transmit Data Byte n+0
PCI Bus
Data Bit-0
Channel 0 to 7 Transmit Data in 32-bit alignment through the Configuration Register Address
0x0100, 0x0300, 0x0500, 0x0700, 0x0900, 0x0B00, 0x0D00 and 0x0F00
THR and RHR Address Locations For CH0 to CH7 (16C550 Compatible)
CH0 0x000 Write THR
CH0 0x000 Read RHR
CH1 0x200 Write THR
CH1 0x200 Read RHR
CH2 0x400 Write THR
CH2 0x400 Read RHR
CH3 0x600 Write THR
CH3 0x600 Read RHR
CH4 0x800 Write THR
CH4 0x800 Read RHR
CH5 0xA00 Write THR
CH5 0xA00 Read RHR
CH6 0xC00 Write THR
CH6 0xC00 Read RHR
CH7 0xE00 Write THR
CH7 0xE00 Read RHR
THRRHR1
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0
Bit-7
Bit-6
Bit-5
Bit-4
Bit-3
Bit-2
Bit-1
Bit-0