Adlink USB-1210 User Manual download pdf (Page 43)

Operation & Calibration 33

USB-1210

All input/output signal polarities can be programmed by software

application. For brevity, all GPTC_CLK, GPTC_GATE, and

GPTC_OUT in the following illustrations are assumed to be active

high or rising-edge triggered.

3.1.7 General Purpose Timer/Counter Modes

Ten programmable timer/counter modes are available. All modes

initialize following a software-start signal set by the software. The

GPTC software reset initializes the status of the counter and

reloads the initial value to the counter. The operation remains

halted until software start is executed again. Operations under dif-

ferent modes are described as follows.

Mode 1: Simple Gated-Event Counting

In this mode, the counter calculates the number of pulses on the

GPTC_CLK after a software start. Initial count can be loaded from

the software application. Current count value can be read back by

software any time with no influence on calculation. GPTC_GATE

enables/disables calculation. When GPTC_GATE is inactive, the

counter halts the current count value. Operation in which initial

count = 5, countdown mode is shown.

Figure 3-14: Mode 1-Simple Gated-Event Calculation

Mode 2: Single Period Measurement

The counter calculates the period of the signal on GPTC_GATE in

terms of GPTC_CLK. The initial count can be loaded from the soft-

ware application. After software start, the counter calculates the

number of active edges on GPTC_CLK between two active edges

55 432110 ffff

Gate

CLK

Count value

Software start

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 53 54

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Adlink USB-1210 User Manual Page 43