Flexcan doesn't apply all filters

Question

I use MK24F12. I adjusted Flexcan module to gather messages from device using Fleet Management Systems Interface. I turned RxFIFO on and set ID acceptance mode as Format A. Then i filled filter table (it starts at 7th mailbox) with IDs and according RXIMR registers with Mask. The rest filters i filled with 0x40000000 and the rest mask registers with 0x5FFFFFFF. When i start to listen to device i get some frames, but here's the problem i don't get all messages device sent, despite they match filters. i know that because if i set any mask register as zero i get all of messages on bus. i noticed that hit filter (RXFIR register) is (0,1,4,5,...), so in other words i get messages which match filters that stored in registers CSn and IDn of MailBox.

Below is log, here i added 7 filters and i got just 4 types of messages. Then i removed all filters and as you can see i skipped a lot of messages that supposed being caught.

[1.003] Filter added (Type: Ext, ID: 0x00FEE900, Mask: 0x00FFFF00)
[1.004] Filter added (Type: Ext, ID: 0x00FEFC00, Mask: 0x00FFFF00)
[1.005] Filter added (Type: Ext, ID: 0x00FEEE00, Mask: 0x00FFFF00)
[1.006] Filter added (Type: Ext, ID: 0x00FEC100, Mask: 0x00FFFF00)
[1.007] Filter added (Type: Ext, ID: 0x00F00400, Mask: 0x00FFFF00)
[1.008] Filter added (Type: Ext, ID: 0x00FEE500, Mask: 0x00FFFF00)
[1.008] Filter added (Type: Ext, ID: 0x00FEEA00, Mask: 0x00FFFF00)

[1.935] CAN.Got frame (Type: Ext, ID: 0x18F00420, Data: FF FF FF 80 0C FF FF FF, Filter: 4)
[2.436] CAN.Got frame (Type: Ext, ID: 0x18FEE520, Data: 58 1C 00 00 FF FF FF FF, Filter: 5)
[2.938] CAN.Got frame (Type: Ext, ID: 0x18FEE920, Data: FF FF FF FF 59 1C 00 00, Filter: 0)
[3.439] CAN.Got frame (Type: Ext, ID: 0x18FEFC20, Data: FF 48 FF FF FF FF FF FF, Filter: 1)
[4.944] CAN.Got frame (Type: Ext, ID: 0x18F00420, Data: FF FF FF C0 12 FF FF FF, Filter: 4)
[5.445] CAN.Got frame (Type: Ext, ID: 0x18FEE520, Data: 59 1C 00 00 FF FF FF FF, Filter: 5)
[6.950] CAN.Got frame (Type: Ext, ID: 0x18FEE920, Data: FF FF FF FF 5A 1C 00 00, Filter: 0)
[7.452] CAN.Got frame (Type: Ext, ID: 0x18FEFC20, Data: FF 46 FF FF FF FF FF FF, Filter: 1)
[8.957] CAN.Got frame (Type: Ext, ID: 0x18F00420, Data: FF FF FF 00 19 FF FF FF, Filter: 4)
[9.458] CAN.Got frame (Type: Ext, ID: 0x18FEE520, Data: 5A 1C 00 00 FF FF FF FF, Filter: 5)


at this point i removed all filters

[34.186] CAN.Got frame (Type: Ext, ID: 0x18F00420, Data: FF FF FF 00 4B FF FF FF, Filter: 0)
[34.688] CAN.Got frame (Type: Ext, ID: 0x18FEE520, Data: 62 1C 00 00 FF FF FF FF, Filter: 0)
[35.190] CAN.Got frame (Type: Ext, ID: 0x18FEE920, Data: FF FF FF FF 63 1C 00 00, Filter: 0)
[35.691] CAN.Got frame (Type: Ext, ID: 0x18FEFC20, Data: FF 34 FF FF FF FF FF FF, Filter: 0)
[36.193] CAN.Got frame (Type: Ext, ID: 0x18FEEE20, Data: 56 FF FF FF FF FF FF FF, Filter: 0)
[36.694] CAN.Got frame (Type: Ext, ID: 0x18FEC120, Data: AD 05 00 00 FF FF FF FF, Filter: 0)
[37.196] CAN.Got frame (Type: Ext, ID: 0x18F00420, Data: FF FF FF 40 51 FF FF FF, Filter: 0)
[37.698] CAN.Got frame (Type: Ext, ID: 0x18FEE520, Data: 63 1C 00 00 FF FF FF FF, Filter: 0)
[39.203] CAN.Got frame (Type: Ext, ID: 0x18FEE920, Data: FF FF FF FF 64 1C 00 00, Filter: 0)
[39.704] CAN.Got frame (Type: Ext, ID: 0x18FEFC20, Data: FF 32 FF FF FF FF FF FF, Filter: 0)
[40.206] CAN.Got frame (Type: Ext, ID: 0x18FEEE20, Data: 58 FF FF FF FF FF FF FF, Filter: 0)
[40.707] CAN.Got frame (Type: Ext, ID: 0x18FEC120, Data: AD 05 00 00 FF FF FF FF, Filter: 0)

Here's picture of FlexCAN registers' values

Answer 1

I have found that I read CODE bits of MB's CS register and it was 1 for filters 2,3,6,7... that means BUSY. But if MB is used by FIFO engine it doesn't contain CODE bits and we shouldn't check Message Buffer Code at all. They might if don't use some bits keep them clear.

Question is closed. Here's picture of MB and FIFO structure