C505_9708 SIEMENS [Siemens Semiconductor Group], C505_9708 Datasheet - Page 156

• Manufacturer Part Number: C505_9708
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

On-Chip Peripheral Components
C505C Only
6.4.7 CAN Controller in Power Saving Modes
Idle mode
In the idle mode of the C505C the CAN controller is fully operable. When a CAN controller interrupt
becomes active and the CAN controller interrupt is enabled, the C505C restarts, returns to normal
operation mode and starts executing the CAN controller interrupt routine.
Slow Down Mode
When the slow down mode is enabled the CAN controller is clocked with the reduced system clock
rate (1/32 of the nominal clock rate). Therefore, also the CAN bit timing in slow down mode is
reduced to 1/32 of the bit timing in normal mode. The slow down mode can be also combined with
idle mode.
Power Down Mode
If the C505C enters software Power Down Mode, the system clock signal is turned off which will
stop the operation of the CAN-Module. Any message transfer is interrupted. In order to ensure that
the CAN controller is not stopped while sending a dominant level (“0”) on the CAN bus, the
microcontroller should set bit INIT in the Control Register prior to entering Power Down Mode. The
microcontroller can check, if a transmission is in progress by reading bits TXRQ and NEWDAT in
the message objects and bit TXOK in the Control Register. After returning from Power Down Mode
the CAN-Module has to be reconfigured.
Semiconductor Group
6-94
1997-08-01