topic Re: How to pack message for FCAN_Send / unpack message for FCAN_Receive in Model-Based Design Toolbox (MBDT)

How to pack message for FCAN_Send / unpack message for FCAN_Receive

johngreenjets — Fri, 19 May 2023 13:04:48 GMT

CAN packing

At the moment I am having to manually pack CAN messages using bit shifts, masks, mux etc in order to construct 8 bytes of data to transmit a CAN message. An example of one such message is shown below...

However, this is very tedious especially when there are lots of CAN messages to pack.

I came across the embedded coder block 'CAN pack' which imports the CAN database, but unfortunately I cannot get this to work.

There is a data type mismatch because the 'CAN Pack' output is not a structure...

The 'CAN pack' block does not seem to output structures...

Should this 'CAN pack' block work with the 'FCAN_Send' block and if so, how ?

If not, is there another way of packing the CAN messages (preferably by importing a CAN database) ?

CAN unpacking

I haven't tried unpacking signals from the 'FCAN_Receive' block yet, so far I have only unpacked the 8 raw bytes of data as shown below...

For testing purposes I have made byte 1 control a digital output (LED).

How can I extract the signals from the 8 bytes of raw data, without having to manually implement the unpacking using bit shifts, masks, mux etc

I tried the embedded coder block 'CAN unpack' which imports the CAN database, but unfortunately I cannot get this to work.

There is a data type mismatch because the 'CAN unpack' input does not allow structures...

Should this 'CAN unpack' block work with the 'FCAN_Receive' block and if so, how ?

If not, is there another way of unpacking the CAN messages (preferably by importing a CAN database) ?

Re: How to pack message for FCAN_Send / unpack message for FCAN_Receive

johngreenjets — Fri, 19 May 2023 13:52:28 GMT

UPDATE:

I have managed to get 'CAN Pack' to work, but I'm not having any luck with 'CAN Unpack'.

To get 'CAN Pack' to work, I set the output as a bus...

The bus elements are shown below...

In this case I selected the bus elements Data, Length and ID to use with the FCAN_Send block.

I tried creating the same bus for 'CAN Unpack', but this did not work...

Re: How to pack message for FCAN_Send / unpack message for FCAN_Receive

johngreenjets — Tue, 23 May 2023 09:22:24 GMT

UPDATE:

I have managed to get 'CAN Unpack' to work as follows:

1. Create the datatype 'CAN_MESSAGE_BUS' by running the command 'canMessageBusType' at the MATLAB prompt. To see the structure of the datatype, run 'CAN_MESSAGE_BUS.Elements'...

2. Create a bus and set the output data type to 'CAN_MESSAGE_BUS'. The inputs to the bus are as follows:

Extended
- datatype uint8
Length
- datatype uint8
Remote
- datatype uint8
Error
- datatype uint8
ID
- datatype uint32
Timestamp
- datatype double
Data
- datatype uint8(8)

3. The following outputs from the NXP Rx Complete block are used as the inputs to the 'CAN Unpack' block...

ID
Data
Length

Re: How to pack message for FCAN_Send / unpack message for FCAN_Receive

Vasappanavara — Fri, 31 May 2024 16:12:44 GMT

Simply awesome John to document your work for the benifit of the community . I am also stuck on this issue , well check on your suggested solution.