TMS320F28335_1 Datasheet, PDF (122/166 Pages) Texas Instruments – Digital Signal Controllers (DSCs)

TMS320F28335, TMS320F28334, TMS320F28332
Digital Signal Controllers (DSCs)
SPRS439B – JUNE 2007 – REVISED OCTOBER 2007
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6.9.3 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
XCLKOUT
GPIOxn
t_w(GPI)
Figure 6-11. General-Purpose Input Timing
NOTE
The pulse-width requirement for general-purpose input is applicable for the
XINT2_ADCSOC signal as well.
122 Electrical Specifications
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