ADV
ANCEINFORMA
TION
GPIOxn
SYSCLK
t
w(GPI)
TMS320F28377S, TMS320F28376S, TMS320F28375S, TMS320F28374S
SPRS881A – AUGUST 2014 – REVISED JUNE 2015
5.7.6.3
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 SYSCLK.
Sampling frequency = SYSCLK/(2 * QUALPRD), if QUALPRD
≠
0
Sampling frequency = SYSCLK, if QUALPRD = 0
Sampling period = SYSCLK cycle x 2 x QUALPRD, if QUALPRD
≠
0
In the above equations, SYSCLK cycle indicates the time period of SYSCLK.
Sampling period = SYSCLK 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 = (SYSCLK cycle x 2 x QUALPRD) x 2, if QUALPRD
≠
0
Sampling window width = (SYSCLK cycle) x 2, if QUALPRD = 0
Case 2:
Qualification using 6 samples
Sampling window width = (SYSCLK cycle x 2 x QUALPRD) x 5, if QUALPRD
≠
0
Sampling window width = (SYSCLK cycle) x 5, if QUALPRD = 0
Figure 5-11. General-Purpose Input Timing
Copyright © 2014–2015, Texas Instruments Incorporated
Specifications
71
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