Table 5-13 Timer and Capture Unit Timing Requirements(1)(2)
|
MIN |
MAX |
UNIT |
tw(TDIR) |
Pulse duration, TDIRx low/high |
Without input qualifier |
2tc(SCO) |
|
cycles |
With input qualifier |
1tc(SCO) + IQT(3) |
|
tw(CAP) |
Pulse duration, CAPx input low/high |
Without input qualifier |
2tc(SCO) |
|
cycles |
With input qualifier |
1tc(SCO) + IQT(3) |
|
tw(TCLKINL) |
Pulse duration, TCLKINx low as a percentage of TCLKINx cycle time |
40 |
60 |
% |
tw(TCLKINH) |
Pulse duration, TCLKINx high as a percentage of TCLKINx cycle time |
40 |
60 |
% |
tc(TCLKIN) |
Cycle time, TCLKINx |
4tc(HCO) |
|
ns |
(1) The QUALPRD bit field value can range from 0 (no qualification) through 0xFF (510 SYSCLKOUT cycles). The qualification sampling period is 2n SYSCLKOUT cycles, where “n” is the value stored in the QUALPRD bit field. As an example, when QUALPRD = 1, the qualification sampling period is 1 × 2 = 2 SYSCLKOUT cycles (that is, the input is sampled every 2 SYSCLKOUT cycles). Six such samples will be taken over five sampling windows, each window being 2n SYSCLKOUT cycles. For QUALPRD = 1, the minimum width that is needed is 5 × 2 = 10 SYSCLKOUT cycles. However, since the external signal is driven asynchronously, a 11-SYSCLKOUT-wide pulse ensures reliable recognition.
(2) Maximum input frequency to the QEP = min[HSPCLK/2, 20 MHz]
(3) Input Qualification Time (IQT) = [tc(SCO) × 2 × QUALPRD] × 5 + [tc(SCO) × 2 × QUALPRD].