UM0459 datasheet(19/29 Pages) STMICROELECTRONICS

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UM0459

Controller area network (CAN) routines

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2.2.12

CAN_ReleaseMessage function

Example:

This example illustrates how to release the message object 0 of CAN2.

{

CAN_ReleaseMessage(CAN2, 0);

}

2.2.13

CAN_SendMessage function

Table 16.

CAN_ReleaseMessage function description

Function name

CAN_ReleaseMessage

Prototype

ErrorStatus CAN_ReleaseMessage(CAN_TypeDef* CAN, u16 msgobj);

Behavior description

Releases the message object.

This function searches for a free message interface from IF0 and IF, sets

the ClrIntPnd and TxRqst/NewDat bits in the Command Mask register

and writes the 1+msgobj value to the Command Request register to copy

the selected registers into the message RAM.

Input parameter 1

CAN: pointer to a CAN1 or CAN2 CAN_TypeDef structure.

Input parameter 2

msgobj: message object number, from 0 to 31.

Output parameter

None

Return value

An ErrorStatus enumeration value:

– SUCCESS: Interface to treat the message

– ERROR: No interface to treat the message

Required preconditions

None

Called functions

CAN_GetFreeIF()

Table 17.

CAN_SendMessage function description

Function name

CAN_SendMessage

Prototype

ErrorStatus CAN_SendMessage(CAN_TypeDef* CAN, u16 msgobj,

canmsg* pCanMsg);

Behavior description

Updates the CAN message object with the pCanMsg fields and starts

the transmission of the message.

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

pCanMsg: Pointer to the canmsg structure that contains the data to

transmit: ID type, ID value, data length, data values.

Output parameter

None

Return value

An ErrorStatus enumeration value:

– SUCCESS: Transmission started OK

– ERROR: No transmission started

Required preconditions

The message object must have been set up properly.

Called functions

CAN_UpdateMsgObj()

CAN_TransmitRequest()

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