TMS320F2809, TMS320F2808, TMS320F2806

TMS320F2802, TMS320F2801, TMS320C2802

TMS320C2801, TMS320F28016, TMS320F28015

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SPRS230L –OCTOBER 2003 –REVISED DECEMBER 2009

6.9.3Sampling 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

XCLKOUT

GPIOxn

tw(GPI)

Figure 6-13. General-Purpose Input Timing

NOTE

The pulse-width requirement for general-purpose input is applicable for the

XINT2_ADCSOC signal as well.

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Texas Instruments TMS320C2801, TMS320F2809, TMS320F2808, TMS320C2802 Sampling Window Width for Input Signals, Case, GPIOxn