NXP Semiconductors MPC5644A, Reference Manual, Page: 874 / 1735

Enhanced Time Processing Unit (eTPU2)
MPC5644A Microcontroller Reference Manual, Rev. 6
874 Freescale Semiconductor
blocks both match recognitions, the match recognition of the other timed task is based on the fact that the
comparator checks greater-equal conditions. It may be delayed if it occurs in the period between the signal
transition detection (which blocks it) and the time TDLA is negated by microcode. If matches are enabled
during the service, the same code can check if the match recognition of the timed task occurred in this
period, by negating TDLA and writing to the CHAN register its own value (in order to update the MRLA
flag in the branch logic).
Either Match, Non Blocking, Double Transition (em_nb_dt)
In this mode each transition is related to one match recognition, and the match recognitions are
independent of each other. This mode can be used to give independent timeout conditions for the first and
the second signal transition recognitions, and call service in any case of any timeout condition.
The first transition detection programmed in IPACA sets TDLA, captures its related timebase, blocks
Match A recognition and enables TDLB assertion. The second transition detection programmed in IPACB
sets TDLB, blocks Match B recognition, captures its related timebase and generates a service request. Any
match recognition that occurs captures its related time base and generates a match service request,
independent on the other match recognition.
Match B Request, Single Transition (m2_st)
On an input signal, this mode provides an open window filter for a single signal transition. MRLA
assertion opens the window, and enables transition detection on TDLA from this time on. MRLB assertion
blocks Match A (by negating MRLEA), providing conditional window opening, because transitions are
indirectly blocked. It also generates service request, but if it happens after Match A it does not block
transitions, providing a non-blocking timeout mechanism for the estimated signal transition time (typically
it indicates a missing transition, or mis-prediction of the transition time).
Transitions can be detected from the microcycle following MRLA assertion. The Transition A detection
asserts TDLA, blocks both matches, captures both timebases and generates service request.
Using this mode, the channel can replace software open window filtering of qualified transitions with the
channel hardware window. The window opening and timeout can be scheduled for any of the two time
bases or combination of them. Typically, Match A will be used to open a prediction window, and Match B
will be used as a timeout condition which does not close the prediction window. This configuration
improves noise immunity from early signal transitions, and reduces the probability for blocking late signal
transitions due to timeout mis-prediction.
Using these conditions, the microcode can easily resolve the state:
• If TDLA and MRLA are asserted and MRLB negated, signal transition is in the expected range.
• If MRLA and MRLB are both asserted, and TDLA is asserted, the signal transition had a timeout
condition due to Match B mis-prediction.
• If MRLB is asserted and TDLA negated, a timeout condition occurred, and the expected signal
transition had not occurred yet.
• If MRLA is negated and MRLB is asserted, the conditional window did not open at all (for
example: a time window is open only after a specific angle, otherwise it is not opened).