NXP Semiconductors MPC5644A, Reference Manual, Page: 1600 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1600 Freescale Semiconductor
33.6.18.2 Protocol status registers
The Protocol Status Register 2 (FR_PSR2) provides slot status information about the Network Idle Time
NIT and the Symbol Window. The Protocol Status Register 3 (FR_PSR3) provides aggregated slot status
information.
33.6.18.3 Slot status registers
The eight slot status registers, Slot Status Registers (FR_SSR0–FR_SSR7) , can be used to observe the
status of static slots, dynamic slots, the symbol window, or the NIT without individual message buffers.
These registers provide all slot status related and received frame / symbol related status information, as
given in
Table 33-126 , except of the first valid indicator for non-transmission slots.
33.6.18.4 Slot status counter registers
The CC provides four slot status error counter registers, Slot Status Counter Registers
(FR_SSCR0–FR_SSCR3) . Each of these slot status counter registers is updated with the value of an
internal slot status counter at the start of a communication cycle. The internal slot status counter is
incremented if its increment condition, defined by the
Slot Status Counter Condition Register
(FR_SSCCR) , matches the status vector provided by the PE. All static slots, the symbol window, and the
NIT status are taken into account. Dynamic slots are excluded . The internal slot status counting and update
timing is shown in Figure 33-159 .
Figure 33-159. Slot status counting and FR_SSCRn update
The PE provides the status of the NIT in the first slot of the next cycle. Due to these facts, the FR_SSCRn
register reflects, in cycle n, the status of the NIT of cycle n-2, and the status of all static slots and the
symbol window of cycle n-1.
The increment condition for each slot status counter consists of two parts, the frame related condition part
and the slot related condition part. The internal slot status counter FR_SSCRn_INT is incremented if at
least one of the conditions is fulfilled:
1. frame related condition:
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communication cycle
static segment dynamic segment symbol window NIT
slot 1
MT
incr. FR_SSCRn_INT
FR_SSCRn = FR_SSCRn_INT
FR_SSCRn_INT not updated
FR_SSCRn = FR_SSCRn_INT
on error
incr. FR_SSCRn_INT
on error
st
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