XR17D158 Exar Corporation, XR17D158 Datasheet - Page 22

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

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PRELIMINARY
The D158 provides 8 multi-purpose inputs/outputs [MPIO7:0] for general use. Each pin can be programmed to
be an input or output function. The input logic state can be set for normal or inverted level, and optionally set to
generate an interrupt. The outputs can be set to be normal logic 1 or 0 state, or 3-state. Their functions and
definitions are programmed through 5 registers: MPIOINT, MPIOLVL, MPIO3T, MPIOINV and MPIOSEL. If all 8
pins are set for inputs, all 8 interrupts would be Or’ed together. The Or’ed interrupt is reported in the channel 0
UART interrupt status, see Interrupt Status Register. The pins may also be programmed to be outputs and to
the 3-state condition for signal sharing.
Bit 7 represents MPIO7 pin and bit 0 represents MPIO0 pin. There are 5 registers that select, control and
monitor the 8 multipurpose inputs and outputs.
MPIOINT [7:0] (default 0x00)
Enable multipurpose input pin interrupt. If the pin is selected by MPIOSEL as input then bit-0 enables input pin
0 for interrupt, and bit-7 enables input pin 7. No interrupt is enable if the pin is selected to be an output. The
interrupt is edge sensing and determined by MPIOINV and MPIOLVL registers. The MPIO interrupt clears after
a read to register MPIOLVL. The combination of MPIOLVL and MPIOINV determines the interrupt being active
low or active high, it’s level trigger. Logic 0 (default) disables the pin’s interrupt and logic 1 enables it.
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2.2.9
2.2.10
Multi-Purpose Inputs and Outputs
MPIO REGISTER
F
IGURE
M PIO IN T [7:0]
M PIO LVL [7:0]
R ea d Inp ut L evel
M PIO IN V [7:0]
(Inp ut In versio n En ab le =1 )
M PIO LVL [7:0]
(O utp ut L evel)
M PIO 3T [7:0]
(3-sta te En ab le = 1)
M PIO SE L [7:0]
(S elect Inpu t=1 , O u tp ut=0 )
IN T
8. M
ULTIPURPOSE INPUT
A N D
R ising Edge
Figure 8
D etection
O R
/
OUTPUT INTERNAL CIRCUIT
1
0
22
UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART
shows the internal circuitry.
A N D
Pin [7:0]
M PIO
M P IO C KT
XR17D158
REV. P1.0.0