Configuration

CAN Hardware Configuration

The following symbols specify CAN Hardware Configuration related parameters and are located in CAN_LPC21xx.c file:

• PCLK (Peripheral CLocK) constant is used to calculate the correct communication speed (baudrate). The value of this constant must be calculated manually and is dependent on VPBDIV and MSEL settings in the Startup file. The value is equal to VPB Clock.

  #define  PCLK            60000000    /* VPB Clock = CPU Clock,
                                          MSEL = 5,
                                          xtal = 12 MHz,
                                          CPU Clock = 60 MHz (MSEL * xtal) */
  

• VIC_NUM_CTRL1_TX .. VIC_NUM_CTRL4_TX specifies which vectored interrupt number to use for message transmission.

  Since transmission is interrupt driven, it is necessary to define unique numbers of interrupts used for each controller's transmission. Acceptable values are 0 .. 15. The lower values have a higher priority.

  #define VIC_NUM_CTRL1_TX       11
  

• VIC_NUM_CTRL1_RX .. VIC_NUM_CTRL4_RX specifies which vectored interrupt number is going to be used for message reception.

  Since reception is interrupt driven, it is necessary to define unique numbers of interrupts used for each controller's reception. Acceptable values are 0 .. 15. The lower values have a higher priority.

  #define VIC_NUM_CTRL1_RX        7
  

CAN Generic Configuration

The following symbols specify CAN Generic Configuration related parameters and are located in CAN_Cfg.h file:

• USE_CAN_CTRL1 .. USE_CAN_CTRL4 enables the CAN controller that will be used. To enable the CAN controller, set this value to 1.

  The RL-CAN uses this information to reserve the memory pool and the memory for software FIFO buffers, as well as to enable interrupts for handling transmission and reception of CAN messages on the specified CAN controller.

  #define USE_CAN_CTRL1           1
  #define USE_CAN_CTRL2           1
  #define USE_CAN_CTRL3           0
  #define USE_CAN_CTRL4           0
  

• CAN_No_SendObjects specifies the size of the software message FIFO buffers for message sending. Each CAN controller reserves a specified size of software buffer to send messages.

  #define CAN_No_SendObjects     20
  

• CAN_No_ReceiveObjects specifies the size of the software message FIFO buffers for message reception. Each CAN controller reserves a specified size of software buffer to receive messages.

  #define CAN_No_ReceiveObjects  20
  

Using Configuration Wizard

You can use the Configuration Wizard to select the parameters as shown in the picture below.

File CAN_LPC21xx.c edited with Configuration Wizard:

File CAN_Cfg.h edited with Configuration Wizard: