StarterWare DCAN

Introduction

The Controller Area network module is a high integrity serial communications protocol for distributed real time applications. The DCAN module present on AM335x is compliant to the CAN 2.0B protocol specification and supports bit-rates upto 1Mbits/s. The core IP for the DCAN controller is provided by Bosch.

Programming sequence

Interrupt Mode

Configuring DCAN for board-board communication

• Platform Related Configurations
  • Configure the system clocks for DCAN peripheral by using the function provided in the platform directory
  • Perform pin mux for DCAN peripherals Tx and Rx pins
  • DCAN message RAM has to be initialized before the peripheral can be enabled for communication. This can be done by calling the function DCANMsgRAMInit
• Initialization and Configuration
  • To place the DCAN in software reset DCANReset API can be used
  • DCAN module can be placed in initialization mode by calling the API DCANInitModeSet
  • Write access to the configuration registers can be enabled or disabled by calling the DCANConfigRegWriteAccessControl API
  • Configuration of CAN bit timing can be done by calling the DCANBitTimingConfig API
  • To enable the status change or error interrupts the DCANIntEnable API can be used
  • To enable the interrupt lines of DCAN peripheral the DCANIntLineEnable API can be used
  • To enable acceptance filtering for a receive message object DCANUseAcceptanceMaskControl and DCANMsgObjectMskConfig APIs can be used.
  • To invalidate a message object the DCANMsgObjInvalidate API can be used
  • To validate a message object the API DCANMsgObjValidate can be used
  • To configure the DCAN command register DCANCommandRegSet API can be used
  • To set the message ID of the CAN frame to be used for communication DCANMsgIdSet API can be used. Configure a receive message object with ID = 0, if CAN frames of any valid IDs(Standard/Extended) should be accepted.
  • To configure the direction of the message object DCANMsgDirectionSet API can be used
  • Data length code(DLC) can be configured using the DCANDataLengthCodeSet API
  • Data bytes to be transmitted as a part of a CAN frame can be written to the interface data registers by using the API DCANDataWrite
  • Message object interrupts can be enabled using the DCANMsgObjIntEnable API
  • Configuration for FIFO end of block control can be done by calling the DCANFIFOEndOfBlockControl API
  • To get the transmit request status the DCANTxRqstStatGet API can be used
  • To get the message valid status of a message object the DCANMsgValidStatusGet API can be used
  • To enable/disable the test modes of DCAN the DCANTestModeControl API can be used
  • To configure DCAN in various test modes the DCANTestModesEnable API can be used
  • Status of the interrupt register can be obtained by using the DCANIntRegStatusGet API
  • Status of DCAN error and status register can be obtained by using the DCANErrAndStatusRegInfoGet API
  • To get CAN bus from bus off to bus on state once the CAN bus errors are within the specified limit the DCANAutoBusOnControl API can be used
  • To clear the interrupt pending status of a message object the DCANCommandRegSet API with appropriate parameter can be used
  • To check the message number and the word number which caused the parity error in that message DCANParityErrCdRegStatusGet API can be used
  • To disable transmit or receive interrupts for a message object DCANMsgObjIntDisable API can be used
  • To read message object data which is transferred from message RAM to the interface register the DCANDataRead API can be used

• Communication
  • To start communication on the CAN bus the DCANNormalModeSet API can be used

Here is a procedural document on enabling the DCAN port in Starterware on the ICEv2. This document also describes a DCAN test between the AM335x GPEVM and the ICEv2.