NXP Semiconductors MPC5644A, Reference Manual, Page: 1596 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1596 Freescale Semiconductor
33.6.16 Strobe signal support
The CC provides a number of strobe signals for observing internal protocol timing related signals in the
protocol engine. The signals are listed and described in
Table 33-12 .
33.6.16.1 Strobe signal assignment
Each of the strobe signals listed in Table 33-12 can be assigned to one of the four strobe ports using the
Strobe Signal Control Register (FR_STBSCR) . To assign multiple strobe signals, the application must
write multiple times to the Strobe Signal Control Register (FR_STBSCR) with appropriate settings.
To read out the current settings for a strobe signal with number N, the application must execute the
following sequence.
1. Write to FR_STBSCR with WMD = 1 and SEL = N. (updates SEL field only)
2. Read STBCSR.
The SEL field provides N and the ENB and STBPSEL fields provides the settings for signal N.
33.6.16.2 Strobe signal timing
This section provides detailed timing information of the strobe signals with respect to the protocol engine
clock.
The strobe signals display internal PE signals. Due to the internal architecture of the PE, some signals are
generated several PE clock cycles before the actual action is performed on the FlexRay Bus. These signals
are listed in
Table 33-12 with a negative clock offset. An example waveform is given in Figure 33-156 .
Figure 33-156. Strobe signal timing (type = pulse, clk_offset = -2)
Other signals refer to events that occurred on the FlexRay Bus some cycles before the strobe signal is
changed. These signals are listed in
Table 33-12 with a positive clock offset. An example waveform is
given in Figure 33-157 .
Figure 33-157. Strobe signal timing (type = pulse, clk_offset = +4)
PE Clock
Strobe Signal
FlexRay Bus Event
-2
PE Clock
Strobe Signal
FlexRay Bus Event
+4