CAN: Denkfehler?

[Joachim .. (joachim_01)]

Ich mach hier grad Versuche (AT91SAM3X8E) um Busnachrichten (Standard 
Message-ID, 11Bit) zu filtern. Die Nachrichten werden von CAN-Modul 0 zu 
Modul 1 geschickt.

Folgende IDs sollen gefiltert werden:
000100 0 11 00  ID0 = 0x08C
000100 0 11 01  ID1 = 0x08D
000100 0 11 10  ID2 = 0x08E
000100 0 11 11  ID3 = 0x08F
000100 1 11 00  ID4 = 0x09C
000100 1 11 01  ID5 = 0x09D
000100 1 11 10  ID6 = 0x09E
000100 1 11 11  ID7 = 0x09F


Das Kochrezept dazu:

The CAN_MIDx (Message ID Nr.x) and CAN_MAMx (message acceptance mask 
Nr.x) of Mailbox x must be initialized to the corresponding values:
CAN_MIDx = 000 100 x 11 xx = 0x08C
CAN_MAMx = 111 111 0 11 00 = 0x7EC
Ok, hab ich verstanden.

Dann:
If Mailbox x receives a message with ID6, then CAN_MIDx and CAN_MFIDx 
are set:
CAN_MIDx  = 000 100 1 11 10 = 0x09E  //ID6
CAN_MFIDx = 000 000 0 01 10 = 0x006  //Filter ID (Atmel benutzt das Wort 
Family ID, ist aber mMn das gleiche wie Filter ID)
Ok.

/**
 *  \brief Test ID mask and Family ID (Filter) from CAN0 Mailbox 0 to CAN1 Mailbox 0.
     Use rotary encoder for different message ID 
 */
void test_7(uint16_t MIDToSend)
{  uint16_t dataToSend;
  static uint8_t uc_suppress = 0;
  if (!uc_suppress) {
    puts("\n\rTest Message Acceptance Mask + FID, SID selected with rotary encoder, CAN0 Mailbox 0 -> CAN1 Mailbox 0"  STRING_EOL);
  uc_suppress = 1;
  }
  can_reset_all_mailbox(CAN0);
  can_reset_all_mailbox(CAN1);
  
    /* Init CAN1 Mailbox 0 to Reception Mailbox. */    
    //  CAN_MIDx  = 000100 x 11 xx = 0x08C
    //  CAN_MAMx  = 111111 0 11 00 = 0x7EC
    //  CAN_MFIDx = 000000 0 01 10 = 0x006
    reset_mailbox_conf(&can1_mailbox);
    can1_mailbox.ul_mb_idx = TEST7_CAN_COMM_MB_IDX; //Mailbox 0...7
    can1_mailbox.uc_obj_type = CAN_MB_RX_MODE;
    can1_mailbox.ul_id_msk =  0x7EC; //CAN_MAM_MIDvA_Msk | CAN_MAM_MIDvB_Msk;
    can1_mailbox.ul_id = CAN_MID_MIDvA(0x08C);// CAN_MID_MIDvA(TEST7_CAN_TRANSFER_ID);
    can1_mailbox.ul_fid = 0x006;      //Filter ID
    can_mailbox_init(CAN1, &can1_mailbox);
  
  
  
  /* Init CAN0 Mailbox 0 to Transmit Mailbox. */
  reset_mailbox_conf(&can0_mailbox);
  can0_mailbox.ul_mb_idx = TEST6_CAN_COMM_MB_IDX;
  can0_mailbox.uc_obj_type = CAN_MB_TX_MODE;
  can0_mailbox.uc_tx_prio = TEST6_CAN0_TX_PRIO;
  can0_mailbox.uc_id_ver = 0;
  can0_mailbox.ul_id_msk = 0;
  can_mailbox_init(CAN0, &can0_mailbox);

  /* Write transmit information into mailbox. */
  can0_mailbox.ul_id = CAN_MID_MIDvA(MIDToSend); // TEST6_CAN_TRANSFER_ID);
  can0_mailbox.ul_datal = (MIDToSend + 0x0100);  //Nachricht...
  can0_mailbox.ul_datah = CAN_MSG_DUMMY_DATA;
  can0_mailbox.uc_length = MAX_CAN_FRAME_DATA_LEN;
  can_mailbox_write(CAN0, &can0_mailbox);

  /* Enable CAN1 mailbox 0 interrupt. */
  can_enable_interrupt(CAN1, CAN_IER_MB0);

  /* Send out the information in the mailbox. */
  can_global_send_transfer_cmd(CAN0, CAN_TCR_MB0);

    while (!g_ul_recv_status); //kommt von CAN-ISR
    // Ab hier nur noch Anzeige
    uint32_t ul_val, ul_val2 = 0;

    puts("Test7 passed" STRING_EOL);
    printf("CAN1 RX Mailbox 0:\r");
  
    ul_val = (uint32_t *)(CAN1->CAN_MB[0].CAN_MDH);
    ul_val2 = (uint32_t *)(CAN1->CAN_MB[0].CAN_MDL);
    printf("Dat Hi:  MDH\t%08X\t\t\tDat Lo:  MDL\t%08X\r", ul_val, ul_val2);
    
    ul_val = (uint32_t *)(CAN1->CAN_MB[0].CAN_MFID);
    ul_val2 = (uint32_t *)(CAN1->CAN_MB[0].CAN_MID);
    printf("FAM ID:  MFID\t%08X\t\t\tID:      MID\t%08X\r\r", ul_val, ul_val2);
}

Bei mir passiert jetzt was ganz seltsames: Bei jeder Aussendung einer 
neuen Standard ID verändert sich die Filter-ID ebenfalls (Ist das der 
Fehler?). Dadurch wird jede Nachricht upgedatet - eine Filterung findet 
nicht statt.

Hab ich was verwexelt? Gehört das so? Fehlt etwas?