C505-2RM SIEMENS [Siemens Semiconductor Group], C505-2RM Datasheet - Page 39

• Manufacturer Part Number: C505-2RM
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

CAN Controller Software Initialization
The very first step of the initialization is the CAN controller input clock selection. A divide-by-2
prescaler is enabled by default after reset (figure 16). Setting bit CMOD (SYSCON.3) disables the
prescaler. The purpose of the prescaler selection is:
Figure 16
CAN Controller Input Clock Selection
Semiconductor Group
.
– to ensure that the CAN controller is operable when
– to achieve the maximum CAN baudrate of 1 Mbaud when
f
Condition: CMOD = 0, when
OSC
Frequency (MHz)
f
Note : The switch configuration shows the reset state of bit CMOD.
OSC
16
8
8
2
f
CAN
8
4
8
f
OSC
(SYSCON.3)
1
0
SYSCON.3
> 10 MHz
(CMOD)
CMOD
1
0
39
(BTR0.0-5)
000000 B
000000 B
000000 B
f
CAN
BRP
f
osc
is over 10 MHz (bit CMOD =0)
f
osc
(Mbaud/sec)
is 8 MHz (bit CMOD=1)
Baudrate
Full-CAN
Module
CAN
0.5
1
1
MCS03296
C505A / C505CA
C505 / C505C
1997-12-01