XR17D158 datasheet(21/73 Pages) EXAR

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XR17D158

REV. 1.2.2

UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART

TIMERMSB [31:24] and TIMERLSB [23:16]

TIMERMSB and TIMERLSB form a 16-bit value. The least-significant bit of the timer is being bit [0] of the

TIMERLSB with most-significant-bit being bit [7] in TIMERMSB. Notice that these registers do not hold the

current counter value when read. Reading the TIMERCNTL register will clear its interrupt. Default value is zero

(timer disabled) upon powerup and reset.

2.2.3

8XMODE [7:0] (default 0x00)

Each bit selects 8X or 16X sampling rate for that UART channel, bit-0 is channel 0. Logic 0 (default) selects

normal 16X sampling with logic one selects 8X sampling rate. Transmit and receive data rates will double by

selecting 8X.

2.2.4

REGA [15:8] Reserved

2.2.5

RESET [23:16] (default 0x00)

The 8-bit Reset register [RESET] provides the software with the ability to reset the UART(s) when there is a

need. Each bit is self-resetting after it is written a logic 1 to perform a reset to that channel. All registers in that

channel will be reset to the default condition, see Table 20 for details. Bit-0 =1 resets UART channel 0 with bit-

7=1 resets channel 7.

TIMERMSB Register

Bit-15 Bit-14 Bit-13 Bit-12 Bit-11 Bit-10

Bit-9 Bit-8

TIMERLSB Register

Bit-7

Bit-6

Bit-5

Bit-4

Bit-3

Bit-2

Bit-1 Bit-0

16-Bit Timer/Counter Programmable Registers

Ch-6

Ch-7

Ch-5 Ch-4 Ch-3 Ch-2 Ch-1 Ch-0

8XMODE Register

Individual UART Channel 8X Clock Mode Enable

Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0

Ch-6

Ch-7

Ch-5 Ch-4 Ch-3 Ch-2 Ch-1 Ch-0

RESET Register

Individual UART Channel Reset Enable

Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0

XR17D158 Datasheet(PDF) 21 Page - Exar Corporation

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