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页码 113
Chapter 4
Signal Connections
©
 National Instruments Corporation
4-31
Figure 4-27 shows the timing requirements for the GPCTR0_GATE 
signal.
Figure 4-27.  GPCTR0_GATE Signal Timing in Edge-Detection Mode
GPCTR0_OUT Signal
This signal is available only as an output on the GPCTR0_OUT pin. 
The GPCTR0_OUT signal reflects the terminal count (TC) of 
general-purpose counter 0. You have two software-selectable output 
options—pulse on TC and toggle output polarity on TC. The output 
polarity is software selectable for both options. This output is set to 
tri-state at startup. Figure 4-28 shows the timing of the GPCTR0_OUT 
signal.
Figure 4-28.  GPCTR0_OUT Signal Timing
GPCTR0_UP_DOWN Signal
This signal can be externally input on the DIO6 pin and is not available 
as an output on the I/O connector. The general-purpose counter 0 will 
count down when this pin is at a logic low and count up when it is at a 
logic high. You can disable this input so that software can control the 
up-down functionality and leave the DIO6 pin free for general use.
Rising-edge
polarity
Falling-edge
polarity
t
w
t
w
= 10 ns minimum
GPCTR0_SOURCE
GPCTR0_OUT
GPCTR0_OUT
(Toggle output on TC)
(Pulse on TC)
TC
PCI_E.book  Page 31  Thursday, June 25, 1998  12:55 PM