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AP29000

Connecting C166 and C500 Microcontroller to CAN

Ways of handling the SAE 81C90/91 and the CAN Module on the C167CR / C515C

Application Note 57 V 1.0, 2004-02

If a Data Frame is received in a receive object (DIR=0) and NEWDAT=0 in the

corresponding Message Control Register, the CAN controller sets NEWDAT and the

data in the Data Field is written into the data bytes of the corresponding receive

object. Additionally, the Arbitration Registers and the data length code of the receive

object are updated with the identifier and the data length code of the received Data

Frame. If RXIE in the corresponding Message Control Register and the global

Interrupt Enable bit (bit IE in the Control Register) is set, the CAN controller sets

INTPND (INterrupt PeNDing) in the Message Control Register which generates an

receive interrupt to the CPU.

In the C167CR, CAN interrupts are controlled via the corresponding Interrupt

Control Register XP0IC. In the C515C, CAN interrupts can be activated /

deactivated via the bit ECAN of the Special Function Register IEN2.

• In the interrupt service routine, the reason for the interrupt (status change interrupt

or interrupt of one of the message objects) can be read from the contents of the

Interrupt Register (the so-called INTID (=INTerrupt IDentifier)). If bit SIE in the

Control Register has been set and the CAN controller updated (not necessarily

changed) the Status Register (which it always does on transmission or reception of

a frame), INTID will have the value "01". If a message has been received, RXOK is

set, if a message has been successfully transmitted, TXOK is set. Read the Status

was received by message object "n", INTID will then have the value "n+2".

After now the message object that has caused the interrupt has been identified, the

data bytes of the message objects can be read and evaluated. Then INTPND and

NEWDAT in the corresponding Message Control Register can be reset:

C167CR:

MCR_Mn = 0xFDFD; /* reset INTPND,NEWDAT of obj. n */

C515C:

MCR0_Mn = 0xFD; /* reset INTPND,NEWDAT of obj. n */

MCR1_Mn = 0xFD

/* RMTPND = unchanged; TXRQ = set */

/* MSGLST = unchanged; NEWDAT = reset */

/* MSGVAL = unchanged; TXIE = unchanged */

/* RXIE = unchanged; INTPND = reset */

Infineon C166 Series User Manual

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