
Chapter 13 FlexRay Communication Controller (FLEXRAY)
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
599
Figure 13-141. Strobe Signal Timing (type = pulse, clk_offset = +4)
13.6.17 Timer Support
The FlexRay block provides two timers, which run on the FlexRay time base. Each timer generates a
maskable interrupt when it reaches a congured point in time. Timer T1 is an absolute timer. Timer T2 can
be congured to be an absolute or a relative timer. Both timers can be congured to be repetitive. In the
non-repetitive mode, timer stops if it expires. In repetitive mode, timer is restarted when it expires.
Both timers are active only when the protocol is in POC:normal active or POC:normal passive state. If
the protocol is not in one of these modes, the timers are stopped. The application must restart the timers
when the protocol has reached the POC:normal active or POC:normal passive state.
13.6.17.1 Absolute Timer T1
The absolute timer T1 has the protocol cycle count and the macrotick count as the time base. The timer 1
Eqn. 13-25
Eqn. 13-26
an interrupt request is generated.
The status bit T1ST is set when the timer is triggered, and is cleared when the timer expires and is non-
repetitive. If the timer expires but is repetitive, the T1ST bit is not cleared and the timer is restarted
immediately. The T1ST is cleared when the timer is stopped.
13.6.17.2 Absolute / Relative Timer T2
The timer T2 can be congured to be an absolute or relative timer by setting the T2_CFG control bit in the
and is cleared when the timer expires and is non-repetitive. If the timer expires but is repetitive, the T2ST
bit is not cleared and the timer is restarted immediately. The T2ST is cleared when the timer is stopped.
13.6.17.2.1
Absolute Timer T2
If timer T2 is congured as an absolute timer, it has the same functionality timer T1 but the conguration
PE Clock
Strobe Signal
FlexRay Bus Event
+4
CYCCTR.CYCCNT & T1CYSR.T1_CYC_MSK == T1CYSR.T1_CYC_VAL & T1CYSR.T1_CYC_MSK
MTCTR.MTCT == TI1MTOR.T1_MTOFFSET