Message buffers availability in s32k148

[juliana_rojas30]

Hello community,

I am reading about the s32k148 board but I am confused about the MBs distribution. As I understand, the MBs are allocated in the RAM dedicated for the FLEX CAN module. 

What I understand about this is that since the FLEX RAM for the s32k144 and the s32k146 is 4K, they are going to support the same quantity of MBs. Meaning that it would be 32 with a payload of 8B.

My confussion is that if the SystemRAM is bigger for the s32k148, wouldn't this allow the FlexRAM to be bigger? Meaning that I could be able to use more MBs for my CAN communication? I don't know if this would be correct to assume or if the only difference would be that the CAN FD is available for the 3 channels. I intend on using only 2 channels, so I don't know if the MBs left could be used for the two of them instead for a 3rd one. 

Any clarification would be appreciated.

Thanks!

[kef2]

Since you mention CAN FD, depending on max payload size setting you are further limited on the number of available MB's. With max payload size set to 64 you have only 7 MB's...  7MB's could be fine if so small amount of MB's wouldn't limit amount of message filters...

Edward

[juliana_rojas30]

Hello @kef2 ,

As you mention, I am working with 7 MBs because of the payload of my CAN FD messages. But I get a huge loss of messages, so I thought that if there was a way for me to use more MBs, the loss would be smaller. I'll have to come up with another solution.

Thanks for your reply!

[PetrS · Accepted solution]

Hi,

each FlexCAN module on S32K148 has 32MBs max. You cannot increase this number if some module is not used. Table 55-1 of the RM shows available MBs per instances for different parts.

BR, Petr