Motorola ColdFire MCF5281 - Manual (Page 492)

FlexCAN
25-22 Freescale Semiconductor
25.5.4 Prescaler Divide Register (PRESDIV)
Table 25-12 describes the PRESDIV fields.
25.5.5 FlexCAN Control Register 2 (CANCTRL2)
Table 25-13 describes the CANCTRL2 fields.
7 0
Field PRES_DIV
Reset 0000_0000
R/W R/W
Address IPSBAR + 0x1C_0008
Figure 25-9. Prescaler Divide Register (PRESDIV)
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:
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.
7 6 5 3 2 0
Field RJW PSEG1 PSEG2
Reset 0000_0000
R/W R/W
Address IPSBAR + 0x1C_0009
Figure 25-10. FlexCAN Control Register 2 (CANCTRL2)
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
S-clock
f
sys
2 PRESDIV + 1
( )
--------------------------------------------- =
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3