TI TMS320F2806 ECAN自测模式，发送确认位的TA不置位

TI TMS320F2806 ECAN自测模式，发送确认位的TA不置位是怎么回事？

// TI File $Revision: /main/4 $

// Checkin $Date: December 3, 2004   13:58:42 $

//###########################################################################

//

// FILE:    Example_280xECanBack2Back.c

//

// TITLE:   DSP280x eCAN Back-to-back transmission and reception in

//          SELF-TEST mode

//

// ASSUMPTIONS:

//

//    This program requires the DSP280x header files.  

//

//    This progrm uses the peripheral's self test mode.

//    Other then boot mode configuration, no other hardware configuration

//    is required.   

//

//    As supplied, this project is configured for "boot to SARAM"

//    operation.  The 280x Boot Mode table is shown below.  

//    For information on configuring the boot mode of an eZdsp,

//    please refer to the documentation included with the eZdsp,  

//

//       Boot      GPIO18     GPIO29    GPIO34

//       Mode      SPICLKA    SCITXDA

//                 SCITXB

//       -------------------------------------

//       Flash       1          1        1

//       SCI-A       1          1        0

//       SPI-A       1          0        1

//       I2C-A       1          0        0

//       ECAN-A      0          1        1        

//       SARAM       0          1        0  <- "boot to SARAM"

//       OTP         0          0        1

//       I/0         0          0        0

//

//

//

// DESCRIPTION:

//

//    This test transmits data back-to-back at high speed without

//    stopping.

//    The received data is verified. Any error is flagged.

//    MBX0 transmits to MBX16, MBX1 transmits to MBX17 and so on....

//    This program illustrates the use of self-test mode

//

//###########################################################################

// Original Author H.J.

//

// $TI Release: DSP280x V1.30 $

// $Release Date: February 10, 2006 $

//###########################################################################

#include "DSP280x_Device.h"     // DSP280x Headerfile Include File

#include "DSP280x_Examples.h"   // DSP280x Examples Include File

// Prototype statements for functions found within this file.

void mailbox_check(int32 T1, int32 T2, int32 T3);

void mailbox_read(int16 i);

// Global variable for this example

Uint32  ErrorCount;

Uint32  PassCount;

Uint32  MessageReceivedCount;

Uint32  TestMbox1 = 0;

Uint32  TestMbox2 = 0;

Uint32  TestMbox3 = 0;

void main(void)

{

    Uint16  j;

// eCAN control registers require read/write access using 32-bits.  Thus we

// will create a set of shadow registers for this example.  These shadow

// registers will be used to make sure the access is 32-bits and not 16.

   struct ECAN_REGS ECanaShadow;

// Step 1. Initialize System Control:

// PLL, WatchDog, enable Peripheral Clocks

// This example function is found in the DSP280x_SysCtrl.c file.

   InitSysCtrl();

// Step 2. Initalize GPIO:

// This example function is found in the DSP280x_Gpio.c file and

// illustrates how to set the GPIO to it's default state.

// InitGpio();  // Skipped for this example  

// For this example, configure CAN pins using GPIO regs here

// This function is found in DSP280x_ECan.c

   InitECanGpio();

// Step 3. Clear all interrupts and initialize PIE vector table:

// Disable CPU interrupts

   DINT;

// Initialize PIE control registers to their default state.

// The default state is all PIE interrupts disabled and flags

// are cleared.  

// This function is found in the DSP280x_PieCtrl.c file.

   InitPieCtrl();

// Disable CPU interrupts and clear all CPU interrupt flags:

   IER = 0x0000;

   IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt

// Service Routines (ISR).  

// This will populate the entire table, even if the interrupt

// is not used in this example.  This is useful for debug purposes.

// The shell ISR routines are found in DSP280x_DefaultIsr.c.

// This function is found in DSP280x_PieVect.c.

   InitPieVectTable();

// Step 4. Initialize all the Device Peripherals:

// This function is found in DSP280x_InitPeripherals.c

// InitPeripherals(); // Not required for this example

// Step 5. User specific code, enable interrupts:

    MessageReceivedCount = 0;

    ErrorCount = 0;

    PassCount = 0;

        //InitECana();

    // eCAN control registers require 32-bit access.

    // If you want to write to a single bit, the compiler may break this

    // access into a 16-bit access.  One solution, that is presented here,

    // is to use a shadow register to force the 32-bit access.

    // Read the entire register into a shadow register.  This access

    // will be 32-bits.  Change the desired bit and copy the value back

    // to the eCAN register with a 32-bit write.

    // Configure the eCAN RX and TX pins for eCAN transmissions

    EALLOW;

    ECanaShadow.CANTIOC.all = ECanaRegs.CANTIOC.all;

    ECanaShadow.CANTIOC.bit.TXFUNC = 1;

    ECanaRegs.CANTIOC.all = ECanaShadow.CANTIOC.all;

    ECanaShadow.CANRIOC.all = ECanaRegs.CANRIOC.all;

    ECanaShadow.CANRIOC.bit.RXFUNC = 1;

    ECanaRegs.CANRIOC.all = ECanaShadow.CANRIOC.all;

    EDIS;

    // Disable all Mailboxes

    // Since this write is to the entire register (instead of a bit

    // field) a shadow register is not required.

    ECanaRegs.CANME.all = 0;

        ECanaShadow.CANTRR.all = ECanaRegs.CANTRR.all;

        ECanaShadow.CANTRR.all=0xFF;

    ECanaRegs.CANTRR.all = ECanaShadow.CANTRR.all;

    // Mailboxs can be written to 16-bits or 32-bits at a time

    // Write to the MSGID field of TRANSMIT mailboxes MBOX0 - 15

    ECanaMboxes.MBOX0.MSGID.all = 0x9555AAA0;

    ECanaMboxes.MBOX1.MSGID.all = 0x9555AAA1;

    ECanaMboxes.MBOX2.MSGID.all = 0x9555AAA2;

    ECanaMboxes.MBOX3.MSGID.all = 0x9555AAA3;

    ECanaMboxes.MBOX4.MSGID.all = 0x9555AAA4;

    ECanaMboxes.MBOX5.MSGID.all = 0x9555AAA5;

    ECanaMboxes.MBOX6.MSGID.all = 0x9555AAA6;

    ECanaMboxes.MBOX7.MSGID.all = 0x9555AAA7;

    ECanaMboxes.MBOX8.MSGID.all = 0x9555AAA8;

    ECanaMboxes.MBOX9.MSGID.all = 0x9555AAA9;

    ECanaMboxes.MBOX10.MSGID.all = 0x9555AAAA;

    ECanaMboxes.MBOX11.MSGID.all = 0x9555AAAB;

    ECanaMboxes.MBOX12.MSGID.all = 0x9555AAAC;

    ECanaMboxes.MBOX13.MSGID.all = 0x9555AAAD;

    ECanaMboxes.MBOX14.MSGID.all = 0x9555AAAE;

    ECanaMboxes.MBOX15.MSGID.all = 0x9555AAAF;

    // Write to the MSGID field of RECEIVE mailboxes MBOX16 - 31

    ECanaMboxes.MBOX16.MSGID.all = 0x9555AAA0;

    ECanaMboxes.MBOX17.MSGID.all = 0x9555AAA1;

    ECanaMboxes.MBOX18.MSGID.all = 0x9555AAA2;

    ECanaMboxes.MBOX19.MSGID.all = 0x9555AAA3;

    ECanaMboxes.MBOX20.MSGID.all = 0x9555AAA4;

    ECanaMboxes.MBOX21.MSGID.all = 0x9555AAA5;

    ECanaMboxes.MBOX22.MSGID.all = 0x9555AAA6;

    ECanaMboxes.MBOX23.MSGID.all = 0x9555AAA7;

    ECanaMboxes.MBOX24.MSGID.all = 0x9555AAA8;

    ECanaMboxes.MBOX25.MSGID.all = 0x9555AAA9;

    ECanaMboxes.MBOX26.MSGID.all = 0x9555AAAA;

    ECanaMboxes.MBOX27.MSGID.all = 0x9555AAAB;

    ECanaMboxes.MBOX28.MSGID.all = 0x9555AAAC;

    ECanaMboxes.MBOX29.MSGID.all = 0x9555AAAD;

    ECanaMboxes.MBOX30.MSGID.all = 0x9555AAAE;

    ECanaMboxes.MBOX31.MSGID.all = 0x9555AAAF;