|
XR16L651 Datasheet, PDF (10/56 Pages) Exar Corporation – 2.25V TO 5.5V UART WITH 32-BYTE FIFO | |||
|
◁ |
XR16L651
2.25V TO 5.5V UART WITH 32-BYTE FIFO
áç
REV. 1.3.0
2.1.1 PC MODE
The PC mode interface includes an on-chip address decoder and interrupt selection function for the standard
PC COM 1-4 port addresses. The selection is made through three input signals: S1, S2 and S3. The selection
summary is shown in Table 1. Although the on-chip address decoder was designed for PC applications ranging
from 0x278 to 0x3FF, it can fit into an embedded applications by offsetting the address lines to the 651. An
example is shown in Figure 6 where the UART is operating from 0x80F8 to 0x80FF address space. Operating
in the PC mode eliminates external address decode components.
TABLE 1: PC MODE INTERFACE ON-CHIP ADDRESS DECODER AND INTERRUPT SELECTION.
PCMODE#
INPUT
S3, S2, S1
INPUTS
A9-A3 ADDRESS LINES TO
ON-CHIP DECODER
COM/LPT PORT
SELECTION
IRQ OUTPUT SELECTION
0
000
0x3F8 - 0x3FF
COM-1
IRQB (for PCâs IRQ4)
0
001
0x2F8 - 0x2FF
COM-2
IRQC (for PCâs IRQ3)
0
010
0x3E8 - 0x3EF
COM-3
IRQB (for PCâs IRQ4)
0
000
0x3F8 - 0x3FF
COM-4
IRQB (for PCâs IRQ4)
0
100
0x2F8 - 0x2FF
COM-1
IRQA (for PCâs IRQn
0
101
0x3E8 - 0x3EF
COM-2
IRQA (for PCâs IRQn)
0
110
0x2E8 - 0x2EF
COM-3
IRQA (for PCâs IRQn)
0
111
0x3F8 - 0x3FF
COM-4
IRQA (for PCâs IRQn)
0
---
0x278 - 0x27F
LPT-2
N/A
0
---
0x378 - 0x37F
LPT-1
N/A
FIGURE 6. PC MODE INTERFACE IN AN EMBEDDED APPLICATION.
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
A3
A4
A5
A6
A7
A14
A15
AEN#
IO R#
IO W #
IN T
RESET
Em bedded Application set to operate
at address 0x80F8 to 0x80FF
VCC
GND
GND
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
AEN*
IO R#
IO W #
IRQ A
IRQ B
IRQ C
S3
S2
S1
RESET
VCC
TX
RX
DTR#
RTS#
CTS#
DSR#
CD#
R I#
OP1#
SEL
GND
VCC
10
|
▷ |