C505_9708 SIEMENS [Siemens Semiconductor Group], C505_9708 Datasheet - Page 122

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

6.4
The Controller Area Network (CAN) bus with its associated protocol allows communication between
a number of stations which are connected to this bus with high efficiency. Efficiency in this context
means:
Note: The CAN interface is a part of the C505C derivatives only.
The CAN interface which is integrated in the C505C is functionally fully compatible with the CAN
module which is available in the 8-bit microcontroller C515C and in the 16-bit microcontroller
C167CR. The CAN module of the C167CR has been adapted with its internal bus interface, clock
generation logic, register access control logic, and interrupt function to the requirements of the 8-bit
C500 microcontroller architecture.
Generally, the CAN interface is made of two major blocks :
The CAN controller is the functional heart which provides all resources that are required to run the
standard CAN protocol (11-bit identifiers) as well as the extended CAN protocol (29-bit identifiers).
It provides a sophisticated object layer to relieve the CPU of as much overhead as possible when
controlling many different message objects (up to 15). This includes bus arbitration, resending of
garbled messages, error handling, interrupt generation, etc. In order to implement the physical
layer, external components have to be connected to the C505C.
The internal bus interface connects the on-chip CAN controller to the internal bus of the
microcontroller. The registers and data locations of the CAN interface are mapped to a specific 256
byte wide address range of the external data memory area (F700 H to F7FF H ) and can be accessed
using MOVX instructions.
Semiconductor Group
– Transfer speed (data rates of up to 1 Mbit/sec can be achieved)
– Data integrity (the CAN protocol provides several means for error checking)
– Host processor unloading (the controller here handles most of the tasks autonomously)
– Flexible and powerful message passing (the extended CAN protocol is supported)
– The CAN controller
– The internal bus interface
The On-Chip CAN Controller
6-60
On-Chip Peripheral Components
C505C Only
1997-08-01