XR17D158 Exar Corporation, XR17D158 Datasheet - Page 20

• Manufacturer Part Number: XR17D158
• Description: Eight-channel Pci-bus Uart
• Manufacturer: Exar Corporation

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PRELIMINARY
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.
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.
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
7=1 resets channel 7.
2.2.3
2.2.4
2.2.5
B it-15 B it-14 B it-13 B it-1 2 B it-11 B it-10
8XMODE [7:0] (default 0x00)
REGA [15:8] RESERVED
RESET [23:16] (default 0x00)
TIM E RM SB Reg ister
C h - 7
Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
1 6 -B it T im e r/C o u n te r P ro g ra m m a b le R e g iste rs
Ch-7
Bit-7 Bit-6 Bit-5 Bit-4 Bit-3 Bit-2 Bit-1 Bit-0
Individual UART Channel 8X Clock Mode Enabl e
C h - 6
Individual UART Channel Reset Enable
Ch-6
B it-9 B it-8
C h - 5 C h - 4 C h - 3 C h - 2 C h - 1 C h - 0
Ch-5 Ch-4 Ch-3 Ch-2 Ch-1 Ch-0
8XMODE Register
RESET Register
Table 19
20
UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART
B it-7
for details. Bit-0 =1 resets UART channel 0 with bit-
B it-6
B it-5
TIM E RLS B Register
B it-4
B it-3
B it-2
B it-1 B it-0
XR17D158
REV. P1.0.0