Renesas RH850 Series Installation and operating instructions

Application Note

R01AN6029EJ0100 Rev.1.0 Page

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May 10, 2017

RH850 Series

CAN Transmit Procedure (CAN FD Mode)

Summary

This document describes an example of a procedure for transmitting CAN using the RH850 series. Please refer to the

notes in the latest user's manual hardware edition for the settings of each register.

Operation Confirmed Devices

This document applies to the RH850 series.

The variables described in the text are as follows.

Table 1-1 Target Devices and Variables

Variable

Target MCU

RH850/E2x

RH850/E1M-S2

RH850/P1M-E

RS-CAN FD channel number

0~4

0~3

0~2

GAFLIDj, GAFLMj, GAFLP0j,

GAFLP1j Register numbers

0~15

Transmit/Receive FIFO buffer

number

0~14

0~11

0~8

Receive FIFO buffer number

0~7

Receive buffer number

0~79

0~63

0~47

Transmit buffer number

0~79

0~63

0~47

RAM test number

0~63

GAFLCFGi、GTINTSTSi

Number of each status register

0~2

0,1

The functions marked with "★" in the text are applicable to cases where 2 or more channels are installed.

In the text, CFD is omitted from the register names.

R01AN6029EJ0100

Rev.1.0

RH850 Series CAN Transmit Procedure (CAN FD Mode)

R01AN6029EJ0100 Rev.1.0 Page

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May 10, 2017

Contents

1. Transmit Function.............................................................................................................3

2. Transmission Using Transmit Buffers...............................................................................4

3. Transmission Using Transmit/Receive FIFO Buffers ......................................................18

4. Transmission Using Transmit Queue..............................................................................26

5. Transmit History Buffer Function ....................................................................................30

6. CAN-related Interrupt Processing...................................................................................36

7. Transmit Data Padding (only in CAN FD mode) .............................................................37

8. Precautions for Processing Flow ....................................................................................38

9. Appendix........................................................................................................................39

RH850 Series CAN Transmit Procedure (CAN FD Mode)

R01AN6029EJ0100 Rev.1.0 Page

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May 10, 2017

1. Transmit Function

The functions that can be used when transmitting CAN messages are shown below. For details on each process, refer

to the following chapters.

•・Transmit using the transmit buffer

•・Transmit using the transmit / receive FIFO buffer

•・Transmit using the transmit queue

•・Transmit history buffer function

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

2. Transmission Using Transmit Buffers

The transmit buffer is used to send data frames or remote frames.

There are 16 transmit buffers per channel, which can be used as a transmit buffer, for linking to the transmit/receive

FIFO buffer (transmit mode, gateway mode★), or a transmit queue.

When using it as a transmit queue for linking to the transmit/receive FIFO buffer (transmit mode, gateway mode★),

set the corresponding TMCp register to "H'00" and the TMIEp bit of the TMIEy register to "0" (interrupt disabled). In

this case, the corresponding flags in the corresponding TMSTSp register, TMTRSTSy register, TMTARSTSy register,

TMTCSTSy register, and TMTARSTSy register do not change.

The functions of the transmit buffer are shown below. For the configuration settings for using the transmit buffer,

refer to "CAN Configuration Application Note".

•・Message transmit function

•・Transmit abort function

•・One-shot transmit function (retransmit prohibition function)

•・Transmit buffer merge mode

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

2.1 Message Transmit Function

This is the function to send data frames or remote frames.

A message can be sent by setting a transmit request in the transmit buffer (the TMTR bit of the TMCp register is

“1”).

The transmission result can be confirmed by the TMTRF [1: 0] flag in the corresponding TMSTSp register. If the

transmission is successful, the transmission is completed: no transmit abort request (the TMTRF [1: 0] flag is “B'10”),

or the transmission is completed: transmit abort required (the TMTRF [1: 0] flag is “B'11”). About the transmission is

completed: transmit abort request (the TMTRF [1: 0] flag is "B'11"), refer to "2.2 Transmit abort function")

For each transmit buffer, interrupt enable/disable when transmission is completed can be set with the TMIEp bit of

the TMIECy register.

Figure 2-1 shows the operation of the transmit buffer.

Figure 2-1 Transmit Buffer Operation (Transmit from channel 0)

Transmit complete interrupt source

activated

Transmit buffer 0

Transmit buffer 1

Transmit buffer 2

Transmit buffer p

Msg1

Msg2

Msg3

Msg1

Msg2

Msg3

CAN Bus

Msg2

Msg3

Programmatically

・Transmit data set

・Transmit request set

Msg1

【Note】Transmit buffer number priority transmission

Note

Msg3

Retransmit when an arbitration

lost or an error occurs

Transmit Data

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

2.1.1 Procedure for Sending Messages from Transmit Buffer

Figure 2-2 shows the procedure for sending messages from the transmit buffer.

【Note】1. For the TMTRF [1: 0] flag in the TMSTSp register, write "B'00" in channel communication mode or

channel standby mode. Do not write any value other than "B'00".

2. Rewrite the TMIDp register, TMPTRp register, and TMDFb_p register when there is no transmit request in

the corresponding transmit buffer (the TMTRM bit of the TMSTSp register is “0”).

3. Do not write to the TMIDP register, TMPTRp register, or TMDFb_p register linked to the transmit/receive

FIFO buffer.

4. When setting the standard ID in the transmit ID (the TMID [28: 0] bit of the TMIDp register), set the ID in

b10 to b0. Set b28-b11 to “0”.

5. This is valid only when the data is stored in the transmit history buffer (the THLDTE bit of the THLCCm

6. Rewrite the TMCp register in channel communication mode or channel standby mode.

7. Set the TMCp register that satisfies the following conditions to "H'00".

Transmit buffer linked to transmit/receive FIFO buffer

Transmit buffer assigned to the transmit queue

8. Set the transmit request (set the TMTR bit of the TMCp register to “1”) when there is no transmit request (the

TMTRF [1: 0] flag in the TMSTSp register is “B’00”).

Figure 2-2 Procedure for Sending Messages from Transmit Buffer

2.2 Transmit Abort Function

If two or more nodes start transmitting at the same time, the node with the lower CAN ID priority will be an

START

Store messages in the transmit buffer *2.、3.

・IDE/RTR/ID*4.

・Enable/disable storage in the transmit history

buffer

・DLC

・Transmit buffer data label*5.

・送信データ

END

Set the transmit request of the corresponding

transmit buffer control register*6.、7.、8.

Yes

Is the transmit buffer status register

"H'00"?

Write "B'00" to the transmission buffer transmit

result flag*1.

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

arbitration lost (the message will be aborted in case of one-shot transmissions, and the message will be retained

(retransmitted) in case of normal transmissions). A message will not be successfully sent unless it is sent without an

arbitration lost or while the CAN bus is idle.

In such cases, there is a transmit abort function to discard the message being retransmitted. The transmit abort

function is effective when you want to set a time limit for sending a message, or when you want to send an urgent

high-priority message.

Figure 2-3 shows an application example of the transmit abort function.

Figure 2-3 Application Example of Transmit Abort Function

Receiving

Send Message

Error

Flame

Resend Message

Receive

Transmit Request

Transmit Abort Request

(1) When you want to set a time limit for sending a message

After a specified time from the start of message transmission, you can set a time limit on message transmission by

requesting a transmit abort.

Error

Arbitration lost

Time Limit

(2) When you want to send an urgent high-priority message

If you perform a transmit abort while sending a message, the message being sent will be discarded after it detects

an arbitration lost or error, and you can send a high-priority message.

Arbitration Lost

Message①Transmit

Receive

Message②Transmit

Transmit Abort Request + Transmit Request of High-priority Message②

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

When a transmit request is issued (the TMTRM bit of the TMSTSp register is “1”) and a transmit abort request is

issued to the transmit buffer (the TMTAR bit of the TMCp register is “1”), the transmit request is cancelled.

The timing of the actual abort after issuing the transmit abort request is shown below.

The message being sent or the message determined to be sent next by the priority determination of transmission

・When an arbitration lost occurs

・When an error occurs

Messages other than the above

・When a transmit abort request is issued

When the transmit abort is completed, the TMTRF [1: 0] flag in the TMSTSp register becomes “B’01” and the

transmit request is canceled (the TMTRM bit becomes “0”).

After issuing a transmit abort request to the message being sent or the message determined to be sent next by the

priority determination of transmission, if the transmission is completed successfully without an arbitration lost or error,

the transmission is completed: There is an abort request (TMTRF [1: 0] flag is “B'11”).

Figure 2-4 shows the operation during transmit abort.

Figure 2-4 Operation during Transmit Abort

Transmit buffer

Msg

CAN Bus

Msg (sending)

Transmit abort interrupt source activated

Transmit abort completed

Stop when an arbitration

lost or an error occurs

Abort request

Transmit buffer

Msg

CAN Bus

Msg

Transmission completion interrupt source activated

occurrence

Programmatically

・Transmit data set

・Transmit request set

(・One-shot request set)

Transmission completed:

There is an abort

request

Abort request

Transmit buffer 0

MsgA

CAN Bus

MsgB

Transmit abort interrupt source activated

Transmit abort completed

before transmission

Abort request

Programmatically

・Transmit data set

・Transmit request set

(・One-shot request set)

MsgB

Transmission

completed

Transmission data

Transmit buffer 1

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

2.2.1 Transmit Abort Procedure

Figure 2-5 shows the procedure for transmit abort.

【Note】1. Rewrite the TMCp register in channel communication mode or channel standby mode.

2. Set the transmit TMCp register that satisfies the following conditions to "H'00".

Transmit buffer linked to the transmit/receive FIFO buffer

Transmit buffer assigned to the transmit queue

3. When there is a transmit request in the transmit buffer (the TMTR bit of the TMCp register is “1”), a transmit

abort request can be issued (the TMTAR bit of the TMCp register is “1”).

4. Depending on the timing, the transmission result will be transmission is completed: There is a transmit abort

(the TMTRF[1:0] flag in the TMSTSp register is "B'11"), so if the transmission result is to be determined,

please check not only if the transmission is complete (TMTRF [1:0] flag is "B'01") but also if the

transmission is completed: There is a transmit abort. Please refer to "2.4.3 Processing procedure after

transmission completion and transmit abort completion" for the procedure for confirming transmission

completion and transmit abort completion.

Figure 2-5 Transmit Abort Procedure

START

END

Set the transmit abort request of the target transmit

buffer*1.、2.、3.、4.

RH850 Series CAN Transmit Procedure (CAN FD Mode)

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May 10, 2017

2.3 One-Shot Transmission Function

When the TMOM bit of the RSCFDn(CFD)TMCp register is set to 1 (one-shot transmission is enabled), transmission is

performed only once. Even if an arbitration lost or an error occurs, retransmission is not performed.

The result of one-shot transmission can be confirmed by the TMTRF [1: 0] flag in the TMSTSp register. If the

one-shot transmission is successful, the transmit buffer transmission result status is transmission complete: no transmit

abort request (TMTRF [1: 0] flag is “B'10”) or transmission complete: There is a transmit abort request (TMTRF [1: 0]

flag will be “B'11”). If an arbitration lost or an error occurs, abort is completed (TMTRF [1: 0] flag is “B’01”). (Refer

to "2.2 Transmit Abort Function" for transmission completion: There is a transmit abort request (TMTRF [1: 0] flag is

"B'11")). Figure 2-6 shows the operation of one-shot transmission.

Figure 2-6 Operation of One-shot Transmission

Transmit buffer

Msg

CAN Bus

Msg

Transmission completion interrupt source activated

Programmatically

・Transmit data set

・Transmit request set

・One-shot request set

Transmit buffer

Msg

CAN Bus

Msg

Transmission

completed

successfully

When an arbitration lost or

an error occurs

Stop when an arbitration

lost or an error occurs

Transmission data

Transmission completion interrupt source activated

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