During the data phase of a CAN FD frame, the transmitter detects a bit error if it cannot
receive its own latest transmitted bit at the sample point of that bit. When bit rate
switching is enabled (BRS bit is asserted), the length of the CAN bit time in the data
phase can become shorter than the transceiver's loop delay, thus impeding the correct
comparison between the transmitted bit and the received bit within the current CAN bit
time interval.
Note that the TDC process defines a secondary sample point where the transmitted bit is
correctly compared with the received bit in order to check for bit errors.
The TDC mechanism can be enabled by FDCTRL[TDCEN] and is effective only during
the data phase of FD frames having the BRS bit set. It has no effect either on non-FD
frames, or on FD frames transmitted at normal bit rate. The TDC is active from the
sample point of the BRS bit until the sample point of the CRC Delimiter bit, provided the
respective message under transmission has the BRS bit set. When it is active, a
comparison is done between the real received bit and the delayed transmitted bit, where
the delay is calculated based on the measured transceiver loop delay.
NOTE
The actual value of the CRC Delimiter bit is disregarded by
transmitters using the transceiver delay compensation
mechanism. A global error at the end of the CRC field will
cause the receivers to send error frames that the transmitter will
detect during Acknowledge or End of Frame.
For every transmitted FD frame having the BRS bit set, the delay measurement is
triggered by the transition from the recessive EDL bit to the dominant R0 bit (as shown in
the next figure). The loop delay is measured in Protocol Engine (PE) clock periods
(CANCLK, see
), from the transmitted EDL-R0 edge to the received
EDL-R0 edge. The position of the secondary sample point is defined by the measured
loop delay time added to an offset value specified in FDCTRL[TDCOFF].
FDCTRL[TDCVAL] stores the result of this calculation. The TDCVAL value saturates at
its maximum value of 63 CANCLK when the delay measurement is too long.
Functional description
MWCT101xS Series Reference Manual, Rev. 3, 07/2019
1688
NXP Semiconductors
Содержание MWCT101 S Series
Страница 2: ...MWCT101xS Series Reference Manual Rev 3 07 2019 2 NXP Semiconductors...
Страница 42: ...MWCT101xS Series Reference Manual Rev 3 07 2019 42 NXP Semiconductors...
Страница 50: ...Conventions MWCT101xS Series Reference Manual Rev 3 07 2019 50 NXP Semiconductors...
Страница 70: ...Aliased bit band regions MWCT101xS Series Reference Manual Rev 3 07 2019 70 NXP Semiconductors...
Страница 78: ...Pinout diagrams MWCT101xS Series Reference Manual Rev 3 07 2019 78 NXP Semiconductors...
Страница 96: ...WCT101xS safety concept MWCT101xS Series Reference Manual Rev 3 07 2019 96 NXP Semiconductors...
Страница 130: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 130 NXP Semiconductors...
Страница 200: ...Initialization application information MWCT101xS Series Reference Manual Rev 3 07 2019 200 NXP Semiconductors...
Страница 284: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 284 NXP Semiconductors...
Страница 430: ...Functional Description MWCT101xS Series Reference Manual Rev 3 07 2019 430 NXP Semiconductors...
Страница 472: ...Application Information MWCT101xS Series Reference Manual Rev 3 07 2019 472 NXP Semiconductors...
Страница 508: ...Reset memory map and register descriptions MWCT101xS Series Reference Manual Rev 3 07 2019 508 NXP Semiconductors...
Страница 528: ...Module clocks MWCT101xS Series Reference Manual Rev 3 07 2019 528 NXP Semiconductors...
Страница 634: ...SRAM configuration MWCT101xS Series Reference Manual Rev 3 07 2019 634 NXP Semiconductors...
Страница 696: ...Initialization and application information MWCT101xS Series Reference Manual Rev 3 07 2019 696 NXP Semiconductors...
Страница 818: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 818 NXP Semiconductors...
Страница 960: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 960 NXP Semiconductors...
Страница 970: ...Memory Map and Register Definition MWCT101xS Series Reference Manual Rev 3 07 2019 970 NXP Semiconductors...
Страница 992: ...ADC calibration scheme MWCT101xS Series Reference Manual Rev 3 07 2019 992 NXP Semiconductors...
Страница 1118: ...Application information MWCT101xS Series Reference Manual Rev 3 07 2019 1118 NXP Semiconductors...
Страница 1294: ...Initialization Procedure MWCT101xS Series Reference Manual Rev 3 07 2019 1294 NXP Semiconductors...
Страница 1348: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 1348 NXP Semiconductors...
Страница 1366: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 1366 NXP Semiconductors...
Страница 1514: ...Functional description MWCT101xS Series Reference Manual Rev 3 07 2019 1514 NXP Semiconductors...
Страница 1726: ...Debug and security MWCT101xS Series Reference Manual Rev 3 07 2019 1726 NXP Semiconductors...
Страница 1740: ...Initialization application information MWCT101xS Series Reference Manual Rev 3 07 2019 1740 NXP Semiconductors...
Страница 1760: ...MWCT101xS Series Reference Manual Rev 3 07 2019 1760 NXP Semiconductors...