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5 canstml and canstmh – can time stamp registers, 6 canmsg – can data message register, 12 examples of can baud rate setting – Rainbow Electronics ATmega64M1 User Manual

Page 197

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197

8209A–AVR–08/09

ATmega16M1/32M1/64M1

• Bit 2 – RTRMSK: Remote Transmission Request Mask

– 0 - comparison true forced

– 1 - bit comparison enabled.

• Bit 1 – Reserved Bit

Writing zero in this bit is recommended.

• Bit 0 – IDEMSK: Identifier Extension Mask

– 0 - comparison true forced

– 1 - bit comparison enabled.

20.11.5

CANSTML and CANSTMH – CAN Time Stamp Registers

• Bits 15:0 - TIMSTM[15:0]: Time Stamp Count

CAN time stamp counter range 0 to 65,535.

20.11.6

CANMSG – CAN Data Message Register

• Bit 7:0 – MSG[7:0]: Message Data

This register contains the CAN data byte pointed at the page MOb register.

After writing in the page MOb register, this byte is equal to the specified message location of the
pre-defined identifier + index. If auto-incrementation is used, at the end of the data register writ-
ing or reading cycle, the index is auto-incremented.
The range of the counting is 8 with no end of loop (0, 1,..., 7, 0,...).

20.12 Examples of CAN Baud Rate Setting

The CAN bus requires very accurate timing especially for high baud rates. It is recommended to
use only an external crystal for CAN operations.

(Refer to

“Bit Timing” on page 171

and

“Baud Rate” on page 173

for timing description and

page

188

to

page 190

for “CAN Bit Timing Registers”).

Bit

7

6

5

4

3

2

1

0

TIMSTM7

TIMSTM6

TIMSTM5

TIMSTM4

TIMSTM3

TIMSTM2

TIMSTM1

TIMSTM0

CANSTML

TIMSTM15 TIMSTM14 TIMSTM13 TIMSTM12 TIMSTM11 TIMSTM10

TIMSTM9

TIMSTM8

CANSTMH

Bit

15

14

13

12

11

10

9

8

Read/Write

R

R

R

R

R

R

R

R

Initial Value

-

-

-

-

-

-

-

-

Bit

7

6

5

4

3

2

1

0

MSG 7

MSG 6

MSG 5

MSG 4

MSG 3

MSG 2

MSG 1

MSG 0

CANMSG

Read/Write

R/W

R/W

R/W

R/W

R/W

R/W

R/W

R/W

Initial Value

-

-

-

-

-

-

-

-