Programmer’s Model

 

 

Table 25-12. PRESDIV Field Descriptions

 

 

 

 

Bits

Name

Description

 

 

 

 

 

7–0

PRES_DIV

Prescaler divide factor. PRESDIV determines the ratio between the system clock frequency and

 

 

 

the serial clock (S-clock). The S-clock is determined by the following calculation:

 

 

 

fsys

 

 

 

S-clock = 2--------------------------------------------(PRESDIV + 1)

 

 

 

The reset value of PRESDIV is 0x00, which forces the S-clock to default to the same frequency

 

 

 

as the system clock. The valid programmed values are 0 through 255. See Section 25.4.8, “Bit

 

 

 

Timing” for more information.

 

 

 

 

 

25.5.5 FlexCAN Control Register 2 (CANCTRL2)

Field

Reset

R/W

Address

7

6

5

3

2

0

RJW

 

PSEG1

 

 

PSEG2

 

 

 

 

 

 

0000_0000

R/W

IPSBAR + 0x1C_0009

Figure 25-10. FlexCAN Control Register 2 (CANCTRL2)

Table 25-13describes the CANCTRL2 fields.

 

 

Table 25-13. CANCTRL2 Field Descriptions

 

 

 

Bits

Name

Description

 

 

 

7–6

RJW

Resynchronization jump width. The RJW field defines the maximum number of time quanta a bit time

 

 

may be changed during resynchronization. The valid programmed values are 0 through 3.

 

 

The resynchronization jump width is calculated as follows:

 

 

Resynchronizaton Jump Width = (RJW + 1) Time Quanta

 

 

 

5–3

PSEG1

PSEG1[2:0] — Phase buffer segment 1. The PSEG1 field defines the length of phase buffer segment

 

 

1 in the bit time. The valid programmed values are 0 through 7.

 

 

The length of phase buffer segment 1 is calculated as follows:

 

 

Phase Buffer Segment 1 = (PSEG1 + 1) Time Quanta

 

 

 

2–0

PSEG2

PSEG2 — Phase Buffer Segment 2. The PSEG2 field defines the length of phase buffer segment 2 in

 

 

the bit time. The valid programmed values are 0 through 7.

 

 

The length of phase buffer segment 2 is calculated as follows:

 

 

Phase Buffer Segment 2 = (PSEG2 + 1) Time Quanta

 

 

 

MOTOROLA

Chapter 25. FlexCAN

25-25

Page 551
Image 551
Motorola MCF5281, MCF5282 FlexCAN Control Register 2 CANCTRL2, 13describes the CANCTRL2 fields, Presdiv Field Descriptions