A. This glitch will be ignored by
the input qualifier. The QUALPRD bit field specifies the qualification sampling
period. It can vary from 00 to 0xFF. If QUALPRD = 00, then the sampling period
is 1 SYSCLK cycle. For any other value "n", the qualification sampling period in
2n SYSCLK cycles (that is, at every 2n SYSCLK cycles, the GPIO pin will be
sampled).
B. The qualification period selected
through the GPxCTRL register applies to groups of eight GPIO pins.
C. The qualification block can take
either three or six samples. The GPxQSELn Register selects which sample mode is
used.
D. In the example shown, for the
qualifier to detect the change, the input should be stable for 10 SYSCLK cycles
or greater. In other words, the inputs should be stable for (5 × QUALPRD × 2)
SYSCLK cycles. This would ensure 5 sampling periods for detection to occur.
Because external signals are driven asynchronously, an 13-SYSCLK-wide pulse
ensures reliable recognition.