UM0459 datasheet(17/29 Pages) STMICROELECTRONICS

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UM0459

Controller area network (CAN) routines

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2.2.11

CAN_SetRxMsgObj function

Table 15.

CAN_SetRxMsgObj function description

Function name

CAN_SetRxMsgObj

Input parameter 1

CAN: pointer to a CAN_TypeDef structure

Prototype

ErrorStatus CAN_SetRxMsgObj(CAN_TypeDef* CAN, u16 msgobj,

u16 idType, u32 idLow, u32 idHigh, bool singleOrFifoLast);

Behavior description

Configures the message object as RX. This message receives all

message objects with id between idLow and idHigh values and whose

id type corresponds to the idType passed as a parameter.

This function performs the following operations:

– Searches for a free message interface from IF0 and IF1.

– Sets the WR/RD, Mask, Arb, Control, DataA and DataB bits in the

Command Mask register.

– Writes the ID mask value generated by idLow and idHigh in the

Mask1 and Mask2 registers,

– Sets M_XTD (to filter according to IDE) and MDIR to filter remote

frames.

– Writes the ID arbitration value generated by idLow and idHigh in the

Arb1 and Arb2 registers, set the MsgVal bit, and also Xtd bit in the

Arb2 register if extended ID is used.

– Sets the RxIE and UMask bits in the Message Control register, and

also the EoB bit if the parameter singleOrFifoLast is TRUE. Clears the

DataA1, DataA2, DataB1, DataB2 registers.

– Writes the value 1+msgobj to the Command Request register to copy

the selected registers into the message RAM.

Input parameter 2

msgobj: message object number, from 0 to 31.

Input parameter 3

idType: the identifier type of the frames that is transmitted using this

message object. The value is one of the following:

CAN_STD_ID (standard ID, 11-bit)

CAN_EXT_ID (extended ID, 29-bit)

Input parameter 4

idLow: the lower part of the identifier range used for acceptance

filtering.

It can have values from 0 to 0x7FF for standard IDs, and values from 0

to 0x1FFFFFFF for extended IDs.

Input parameter 4

idHigh: the higher part of the identifier range used for acceptance

filtering.

It can have values from 0 to 0x7FF for standard IDs, and values from 0

to 0x1FFFFFFF for extended IDs.

idHigh must be above idLow.

For convenience, use one of the following values to set the maximum

ID: CAN_LAST_STD_ID or CAN_LAST_EXT_ID

Input parameter 5

singleOrFifoLast: End-of-buffer indicator, it can have the following

values:

– TRUE for a single receive object or a FIFO receive object that is the

last one in the FIFO

– FALSE for a FIFO receive object that is not the last one

Output parameter

None

Return value

An ErrorStatus enumeration value:

– SUCCESS: Interface to handle the message

– ERROR: No interface to handle the message

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