TMS320F28023DAS datasheet(95/130 Pages) TI

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GPIOxn

XCLKOUT

tw(GPI)

TMS320F28027, TMS320F28026, TMS320F28023, TMS320F28022

TMS320F28021, TMS320F28020, TMS320F280200

www.ti.com

SPRS523F – NOVEMBER 2008 – REVISED DECEMBER 2010

6.10.3 Sampling Window Width for Input Signals

The following section summarizes the sampling window width for input signals for various input qualifier

configurations.

Sampling frequency denotes how often a signal is sampled with respect to SYSCLKOUT.

Sampling frequency = SYSCLKOUT/(2 * QUALPRD), if QUALPRD

≠ 0

Sampling frequency = SYSCLKOUT, if QUALPRD = 0

Sampling period = SYSCLKOUT cycle x 2 x QUALPRD, if QUALPRD

≠ 0

In the above equations, SYSCLKOUT cycle indicates the time period of SYSCLKOUT.

Sampling period = SYSCLKOUT cycle, if QUALPRD = 0

In a given sampling window, either 3 or 6 samples of the input signal are taken to determine the validity of

the signal. This is determined by the value written to GPxQSELn register.

Case 1:

Qualification using 3 samples

Sampling window width = (SYSCLKOUT cycle x 2 x QUALPRD) x 2, if QUALPRD

≠ 0

Sampling window width = (SYSCLKOUT cycle) x 2, if QUALPRD = 0

Case 2:

Qualification using 6 samples

Sampling window width = (SYSCLKOUT cycle x 2 x QUALPRD) x 5, if QUALPRD

≠ 0

Sampling window width = (SYSCLKOUT cycle) x 5, if QUALPRD = 0

Figure 6-12. General-Purpose Input Timing

Electrical Specifications

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TMS320F28023DAS Datasheet(PDF) 95 Page - Texas Instruments