NXP Semiconductors PXN2020, Reference Manual, Page: 759 / 1376

FlexRay Communication Controller (FlexRAY)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 26-145
26.6.18.2 Protocol Status Registers
The Protocol Status Register 2 (PSR2) provides slot status information about the Network Idle Time NIT
and the Symbol Window. The Protocol Status Register 3 (PSR3) provides aggregated slot status
information.
26.6.18.3 Slot Status Registers
The eight slot status registers, Slot Status Registers (SSR0–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 26-116 , except of the first valid indicator for non-transmission slots.
26.6.18.4 Slot Status Counter Registers
The controller provides four slot status error counter registers, Slot Status Counter Registers
(SSCR0–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 (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 26-149 .
Figure 26-149. Slot Status Counting and SSCRn Update
The PE provides the status of the NIT in the first slot of the next cycle. Due to these facts, the SSCR n
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.
cycle s
tart
sl
ot start
slot s
tart
sy
m
bol window s
tart
MT
st
at
us(NIT)
MT
st
at
us(slot
1)
st
at
us(slot
k)
MT
st
at
us(slot
n)
MT
NI
T star
t
st
at
us(sym.
win)
MT
cycle st
art
st
at
us(NIT)
communication cycle
static segment dynamic segment symbol window NIT
slot 1
MT
incr. SSCRn_INT on error incr. SSCRn_INT on error
SSCRn:= SSCRn_INT
SSCRn_INT not updated
SSCRn:= SSCRn_INT