Texas Instruments TMS320 2833 Series User Manual

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97
SPRUI07–March 2020
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System Control and Interrupts
Number of samples:
The number of times the signal is sampled is either 3 samples or 6 samples as specified in the
qualification selection (GPAQSEL1, GPAQSEL2, GPBQSEL1, and GPBQSEL2) registers. When 3 or 6
consecutive cycles are the same, then the input change will be passed through to the DSP.
Total Sampling Window Width:
The sampling window is the time during which the input signal will be sampled as shown in Figure 1-46.
By using the equation for the sampling period along with the number of samples to be taken, the total
width of the window can be determined.
For the input qualifier to detect a change in the input, the level of the signal must be stable for the duration
of the sampling window width or longer.
The number of sampling periods within the window is always one less then the number of samples taken.
For a thee-sample window, the sampling window width is 2 sampling periods wide where the sampling
period is defined in Table 1-42. Likewise, for a six-sample window, the sampling window width is 5
sampling periods wide. Table 1-44 and Table 1-45 show the calculations that can be used to determine
the total sampling window width based on GPxCTRL[QUALPRDn] and the number of samples taken.
Table 1-44. Case 1: Three-Sample Sampling Window Width
Total Sampling Window Width
If GPxCTRL[QUALPRDn] = 0 2 × T
SYSCLKOUT
If GPxCTRL[QUALPRDn] ≠ 0 2 × 2 × GPxCTRL[QUALPRDn] × T
SYSCLKOUT
Where T
SYSCLKOUT
is the period in time of SYSCLKOUT
Table 1-45. Case 2: Six-Sample Sampling Window Width
Total Sampling Window Width
If GPxCTRL[QUALPRDn] = 0 5 × T
SYSCLKOUT
If GPxCTRL[QUALPRDn] ≠ 0 5 × 2 × GPxCTRL[QUALPRDn] × T
SYSCLKOUT
Where T
SYSCLKOUT
is the period in time of SYSCLKOUT
NOTE: The external signal change is asynchronous with respect to both the sampling period and
SYSCLKOUT. Due to the asynchronous nature of the external signal, the input should be
held stable for a time greater than the sampling window width to make sure the logic detects
a change in the signal. The extra time required can be up to an additional sampling period +
T
SYSCLKOUT
.
The required duration for an input signal to be stable for the qualification logic to detect a
change is described in the device specific data manual.

Texas Instruments TMS320 2833 Series Specifications

General

Brand	Texas Instruments
Model	TMS320 2833 Series
Category	Controller
Language	English