UM0459 datasheet(21/29 Pages) STMICROELECTRONICS

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UM0459

Controller area network (CAN) routines

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2.2.16

CAN_ReceiveMessage function

Example:

This example illustrates how to receive a message.

{

canmsg CanMsg;

/*Receive a message in the object 0 and ask for release*/

if (CAN_ReceiveMessage(CAN1, 0, TRUE, &CanMsg))

{

/*Check or copy the message contents*/

}

else

{

/* Error handling*/

}

Table 20.

CAN_ReceiveMessage function description

Function name

CAN_ReceiveMessage

Prototype

ErrorStatus CAN_ReceiveMessage(CAN_TypeDef* CAN, u16

msgobj, bool release, canmsg* pCanMsg);

Behavior description

Gets the message, if received.

This function performs the following operations:

– Tests the bit corresponding to the message object number in the

NewData registers.

– Clears the RxOk bit in the Status register.

– Copies the message contents from the message RAM to the registers

and to the structure, and releases the message object if asked.

Input parameter 1

CAN: pointer to a CAN1 or CAN2 CAN_TypeDef structure.

Input parameter 2

msgobj: message object number, from 0 to 31.

Input parameter 3

Release: message release indicator, it can have the following values:

– TRUE: the message object is released at the same time as it is copied

from message RAM, then it is free for next reception

– FALSE: the message object is not released, it is up to the caller to

release it

Input parameter 4

pCanMsg: pointer to the canmsg structure where the received message

is copied.

Output parameter

None

Return value

An ErrorStatus enumeration value:

– SUCCESS: Reception OK

– ERROR: No reception

Required preconditions

The message object must have been set up properly.

Called functions

CAN_GetFreeIF()

CAN_GetMsgReceiveStatus()

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