ADLINK Technology USB-1901, User Manual

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Operation 57
USB-1900 Series
4.6.2 General Purpose Timer/Counter
The USB-1900 Series is equipped with two general purpose timer/
counter sets featuring:
X Count up/down controllable by hardware or software
X Programmable counter clock source (internal clock up to 80
MHz, external clock up to 10 MHz)
X Programmable gate selection (hardware or software con-
trol)
X Programmable input and output signal polarities (high active
or low active)
X Initial Count loaded from a software application
X Current count value readable by software without affecting
circuit operation.
Table 4-5: Timer/Counter Pin Definition
4.7 Basic Timer/Counter Function
Each timer/counter has three inputs that can be controlled via
hardware or software. They are clock input (GPTC_CLK), gate
input (GPTC_GATE), and up/down control input (GPTC_UD). The
GPTC_CLK input provides a clock source input to the timer/coun-
ter. Active edges on the GPTC_CLK input increment or decrement
the counter. The GPTC_UD input directs the counter to count up
Pin Function Pin Function
38 GPTC_AUX2
17 GPTC_OUT3 37 GPTC_GATE2
16 GPTC_OUT2 36 GPTC_UD2
15 GPTC_OUT1 35 GPTC_CLK2
14 GPTC_OUT0 34 GPTC_AUX0
13 DGND 33 GPTC_GATE0
32 GPTC_UD0
31 GPTC_CLK
30 DGND