Embedded Target for Motorola MPC555

CAN Calibration Protocol

Implement the CAN Calibration Protocol (CCP) standard

Library

Embedded Target for Motorola MPC555

Description

The CAN Calibration Protocol block provides an implementation of a subset of the CAN Calibration Protocol (CCP Version 2.1). CCP is a protocol for communicating between the target processor and the host machine over CAN. In particular, a calibration tool (see Compatibility with Calibration Packages) running on the host can communicate with the target, allowing remote signal monitoring and parameter tuning.

This block processes a Command Receive Object (CRO) and outputs the resulting Data Transmission Object (DTO) and Data Acquisition Messages (DAQ).

For more information on CCP refer to ASAM Standards: ASAM MCD: MCD 1a on the Association for Standardization of Automation and Measuring Systems (ASAM) Web site:

http://www.asam.de

Block Inputs and Outputs

The CAN Calibration Protocol block inputs are

• f(): a function call trigger input.
• CRO: a CAN message. The expected data source is a block such as a CAN Receive block. The message received at the CRO input is read when a trigger is received at the Fcn- Call input.

The block outputs are

• f() DTO: a function call trigger output.
• DTO: a CAN message. DTO should be read by the receiving block when it receives the f() DTOl trigger.
• f() DAQ: a function call trigger output.
• DAQ: a CAN message. DAQ should be read by the receiving block when it receives the f() DAQ trigger.

These inputs and outputs can be used to set up generic data I/O for the block.

Using the DAQ Output

The DAQ output is the output for any CCP Data Acquisition Lists that have been set up. You can use the ASAP2 file generation feature of the RT target to

• Set up signals to be transmitted using CCP Data Acquisition Lists.
• Assign signals in your model to a CCP Event Channel automatically (see Generating ASAP2 Files).

Once these signals are set up, Event Channels then periodically fire events that trigger the transmission of DAQ data to the host. When this occurs, CAN messages with the appropriate CCP / DAQ data appear on the DAQ output, along with an associated function call trigger.

It is the responsibility of the calibration tool (see Compatibility with Calibration Packages) to use CCP commands to assign an Event Channel and data to the available DAQ lists, and to interpret the synchronous response.

Using DAQ lists for signal monitoring has the following advantages over the polling method:

• There is no need for the host to poll for the data. Network traffic is halved.
• The data is transmitted at the correct update rate for the signal. Therefore there is no unnecessary network traffic generated.
•     Data is guaranteed to be consistent. The transmission takes place after the signals have been updated, so there is no risk of interruptions while sampling the signal.

Note    The Embedded Target for Motorola MPC555 does not currently support event channel prescalers.

Dialog Box

CAN station address (16 bit integer)

The station address of the target. The station address is interpreted as a uint16. It is used to distinguish between different targets. By assigning unique station addresses to targets sharing the same CAN bus, it is possible for a single host to communicate with multiple targets.

CAN message identifier (DTO/DAQ)

The message identifier is the CAN message ID used for both CAN message block outputs. It is also used for transmitting messages to the host during the software-induced CAN download (soft boot). See Extended Functionality below.

CAN message type (DTO/DAQ)

The message type to be transmitted by the DTO and DAQ outputs. Select either Standard(11-bit identifier) or Extended(29-bit identifier).

Total number of Object Descriptor Tables (ODTs)

CCP provides up to 254 Object Descriptor Tables (ODTs) that are shared between all available Data Acquisition Lists. This implementation shares these ODTs equally between the available DAQ Lists.

A single ODT uses 56 bytes of memory. Using all 254 ODTs would require over 14 KB of memory, a large proportion of the available memory on the target. If you need to conserve memory on the target, you can reduce the total number of ODTs, allowing DAQ List signal monitoring with reduced memory overhead.

Supported CCP Commands

The following CCP commands are supported by the CAN Calibration Protocol block:

• CONNECT
• DISCONNECT
• DNLOAD
• DNLOAD_6
• EXCHANGE_ID
• GET_CCP_VERSION
• GET_DAQ_SIZE
• GET_S_STATUS
• SET_DAQ_PTR
• SET_MTA
• SET_S_STATUS
• SHORT_UP
• START_STOP
• START_STOP_ALL
• TEST
• UPLOAD
• WRITE_DAQ

Compatibility with Calibration Packages

The above commands support:

• Synchronous signal monitoring via calibration packages that use DAQ Lists
• Asynchronous signal monitoring via calibration packages that poll the target
• Asynchronous parameter tuning via CCP Memory Programming

This CCP implementation has been tested successfully with the Vector-Informatik CANape calibration package running in both DAQ List and Polling mode, and with the Accurate Technologies Inc. Vision calibration package running in DAQ List mode. (Note that Accurate Technologies Inc. Vision does not support the Polling mechanism for signal monitoring).

Extended Functionality

The CAN Calibration Protocol block also supports the PROGRAM_PREPARE command. This command is an extension of CCP that allows the automatic download of new code into the target memory. On receipt of the PROGRAM_PREPARE command, the target will reboot and begin the CAN download process. This lets you download new application code to RAM or flash memory, or download new boot code to flash memory.

Note    The CAN message identifier of the incoming CCP messages (CRO), and that specified in the block mask for CAN message identifier (DTO/DAQ) are used as the CAN identifiers for the download process after a PROGRAM_PREPARE reboot. The type of CAN message used for this PROGRAM_PREPARE download process is always Extended (29-bit identifier).

Alphabetical List of Blocks

CAN Message Filter