UM10430 Datasheet, PDF (1104/1164 Pages) NXP Semiconductors – LPC18xx ARM Cortex-M3 microcontroller

UM10430 NXP Semiconduct_RRPopdoo_acorreeocr_rnsmsts_{cueeeieratntrotstreiobnnksnuog:nctsrhToetehBhtaoeveScfflatyPIiiaNnl,vidiibsIsttTiiyueedantqsulbictzurihathiaenenrftngioidnoMcnsinsesieozhtoasfoeetfsrwfsstta1shaigt1terhsteeheecMeolOifnsenmtbiotossijfeaseettwsalcchizsgatuesaaertiedtgsviOoaeheinntobatrirujtebeaitlacerdcnaleftisozsansfarlessilestfirbive.otieehnrnedo.cbenoAiBtpsn}^D_fStteh^R_fe(iPn^A_egBrdw^F_usuC^T_ertaseaA^D_{nrdrIRdtNdtAsso}^DC_tlFoe^R_bfttThh)^A_hIupNaDe^F_ebsa^TRp_{IemrTBbADttfeioyFiRecatTrrADuswnSeDFR4sldaatTRAia2rtriAe}^F_aDtg:ci^TF_{iaRlnedAsaTADmgeontpDFRrnTfRDAacptotaARFDanierfTkFARnisnetTe}^FAD_fhdrbe^TDFR_{seierTRDAx.ARDFTFDARTRFADTADFRTFRDATADRF}
To change the configuration of a Message Object during normal operation, the CPU has to
start by setting the MSGVAL bit to not valid. When the configuration is completed,
MSAGVALis set to valid again.
42.10.7.2.2 CAN message transfer
Once the CAN controller is initialized and INIT is reset to zero, the CAN core synchronizes
itself to the CAN bus and starts the message transfer.
Received messages are stored into their appropriate Message Objects if they pass the
Message Handler’s acceptance filtering. The whole message including all arbitration bits,
DLC and eight data bytes is stored into the Message Object. If the Identifier Mask is used,
the arbitration bits which are masked to “don’t care” may be overwritten in the Message
Object.
The CPU may read or write each message any time via the Interface Registers. The
Message Handler guarantees data consistency in case of concurrent accesses.
Messages to be transmitted are updated by the CPU. If a permanent Message Object
(arbitration and control bits set up during configuration) exists for the message, only the
data bytes are updated and then TXRQUT bit with NEWDAT bit are set to start the
transmission. If several transmit messages are assigned to the same Message Object
(when the number of Message Objects is not sufficient), the whole Message Object has to
be configured before the transmission of this message is requested.
The transmission of any number of Message Objects may be requested at the same time,
and they are transmitted subsequently according to their internal priority. Messages may
be updated or set to not valid any time, even when their requested transmission is still
pending. The old data will be discarded when a message is updated before its pending
transmission has started.
Depending on the configuration of the Message Object, the transmission of a message
may be requested autonomously by the reception of a remote frame with a matching
identifier.
42.10.7.2.3
Disabled Automatic Retransmission (DAR)
According to the CAN Specification (ISO11898, 6.3.3 Recovery Management), the CAN
controller provides means for automatic retransmission of frames that have lost arbitration
or that have been disturbed by errors during transmission. The frame transmission service
will not be confirmed to the user before the transmission is successfully completed. By
default, the automatic retransmission on lost arbitration or error is enabled. It can be
disabled to enable the CAN controller to work within a Time Triggered CAN (TTCAN, see
ISO11898-1) environment.
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User manual
All information provided in this document is subject to legal disclaimers.
Rev. 00.13 — 20 July 2011
© NXP B.V. 2011. All rights reserved.
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