XR17V252_08 Datasheet, PDF (22/69 Pages) Exar Corporation – 66 MHZ PCI BUS DUAL UART WITH POWER MANAGEMENT SUPPORT

XR17V252
66 MHZ PCI BUS DUAL UART WITH POWER MANAGEMENT SUPPORT
REV. 1.0.2
1.6.9 Multi-Purpose Inputs and Outputs
The V252 provides 8 multi-purpose inputs/outputs MPIO[7:0] 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 HIGH or LOW 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. The MPIO[0] pin can be programmed to show the Timer output. When
it is programmed to be the Timer output, all the above 5 registers lose control over the MPIO[0] pin. For details
on Timer output, please see “Section 1.6.2, General Purpose 16-bit Timer/Counter [TIMERMSB,
TIMELSB, TIMER, TIMECNTL] (default 0xXX-XX-00-00)” on page 17.
1.6.10 MPIO REGISTER
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. Figure 9 shows the internal circuitry.
FIGURE 9. MULTIPURPOSE INPUT/OUTPUT INTERNAL CIRCUIT
MPIOINT [7:0]
INT
AND
Rising Edge
Detection
AND
MPIOLVL [7:0]
Read Input Level
MPIOINV [7:0]
(Input Inversion Enable =1)
MPIOLVL [7:0]
(Output Level)
MPIO3T [7:0]
(3-state Enable =1)
MPIOSEL [7:0]
(Select Input=1, Output=0 )
1
0
OR
MPIO
Pin [7:0]
MPIOCKT
22