Simple Frage zum Canbus zu TI DSPs

Sebastian Gast #3855043
Lesenswert?
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Hallo zusammen,

ich möchte gerne zwischen zwei Microcontrollern (beide F28335) per 
CAN-Bus kommunizieren. Dazu habe ich von den beiden gleichen 
Microcontrollern die Pins 30 miteinander verbunden (CANTXA) und auch die 
Pins 31 von beiden (CANRXA). Zwichen diesen beiden Leitungen (nur ein 
paar Zentimeter lang) habe ich ein 68 Ohm Widerstand gebastelt (anstelle 
von 2 120 Ohm Wid. an den Enden).

Die beiden Programme für die Senderseite- und Empfängerseite sind hier 
aufgelistet:
Senderseite:
1
 /*

2
 * This script is intended to send messages on eCANA

3
 * Messages are send to the message box address: 0xFF

4
 * */

5


6


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#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File

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// Prototype statements for functions found within this file.

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void delay();

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void Gpio_select(void);

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void SendCANMsg(int16 MBXnum,  Uint32 MBXDL,  Uint32 MBXDH);

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// CAN

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#define CAN_TARGET_MAILBOX_ADDRESS 0xFF

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#define CAN_BITS_SEND 4

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void main(void)

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{

21


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

23
    // will create a set of shadow registers for this example.  These shadow

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

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    struct ECAN_REGS ECanaShadow;

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    struct ECAN_MBOXES ECanMboxShadow;

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    // Step 1. Initialize System Control:

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    // PLL, WatchDog, enable Peripheral Clocks

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    // This example function is found in the DSP2833x_SysCtrl.c file.

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      InitSysCtrl();

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  // Step 2. Initalize GPIO:

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  // This example function is found in the DSP2833x_Gpio.c file and

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

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

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  Gpio_select(); // for LEDs

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  InitECanaGpio(); //for CAN bus

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

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// Disable CPU interrupts

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  DINT;

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// Initialize the PIE control registers to their default state.

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

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// are cleared.

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// This function is found in the DSP2833x_PieCtrl.c file.

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  InitPieCtrl();

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

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  IER = 0x0000;

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  IFR = 0x0000;

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

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// Service Routines (ISR).

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

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

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// The shell ISR routines are found in DSP2833x_DefaultIsr.c.

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// This function is found in DSP2833x_PieVect.c.

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  InitPieVectTable();

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// Step 5. User specific code, enable interrupts

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  // CAN

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  InitECana(); // Initialize eCAN-A module

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  ECanaRegs.CANME.all = 0x00000000; // Disable all mailboxes

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  // Transmitting MBOX1

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  ECanMboxShadow.MBOX1.MSGID.bit.STDMSGID = CAN_TARGET_MAILBOX_ADDRESS;

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  ECanaMboxes.MBOX1.MSGID.all = ECanMboxShadow.MBOX1.MSGID.all;

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  ECanaShadow.CANMD.all = ECanaRegs.CANMD.all;

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   ECanaShadow.CANMD.bit.MD1 = 0;    // Mailbox 1 : transmitting mailbox

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   ECanaRegs.CANMD.all = ECanaShadow.CANMD.all;

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// Enable Mailboxes

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   ECanaShadow.CANME.all = ECanaRegs.CANME.all;

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   ECanaShadow.CANME.bit.ME1 = 1;

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   ECanaRegs.CANME.all = ECanaShadow.CANME.all;

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   ECanaMboxes.MBOX1.MSGCTRL.bit.DLC = CAN_BITS_SEND;

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   ECanaMboxes.MBOX1.MSGCTRL.bit.RTR = 0;

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   GpioDataRegs.GPBDAT.bit.GPIO34 = 1;//LED3 off

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// Step 6. IDLE loop. Just sit and loop forever (optional):

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   for(;;)

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   {

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     SendCANMsg(1,  2,  3);

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     if(GpioDataRegs.GPBDAT.bit.GPIO34)

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       GpioDataRegs.GPBDAT.bit.GPIO34 = 0;//LED3 on

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     else

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       GpioDataRegs.GPBDAT.bit.GPIO34 = 1;//LED3 off

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       delay();

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   }

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}

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void SendCANMsg(int16 MBXnum,  Uint32 MBXDL,  Uint32 MBXDH)

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{

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    volatile struct MBOX *srcMBox;

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    if (0 <= MBXnum && MBXnum <= 32)

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    {

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        Uint32 MBXflag = (0x00000001 << MBXnum);

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        srcMBox = &ECanaMboxes.MBOX0 + MBXnum;

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        srcMBox->MDL.all = MBXDL;

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        srcMBox->MDH.all = MBXDH;

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        ECanaRegs.CANTRS.all = MBXflag;

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        while(ECanaRegs.CANTA.all != MBXflag) {}

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        ECanaRegs.CANTA.all = MBXflag;

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    }

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}

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void delay()

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{

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  double i;

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  for (i = 0; i < 2000000; i++)

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  {

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  }

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}

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void Gpio_select(void)

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{

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132


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    EALLOW;

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  GpioCtrlRegs.GPAMUX1.all = 0x00000000;  // All GPIO

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  GpioCtrlRegs.GPAMUX2.all = 0x00000000;  // All GPIO

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  GpioCtrlRegs.GPAMUX1.all = 0x00000000;  // All GPIO

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    GpioCtrlRegs.GPADIR.all = 0xFFFFFFFF;   // All outputs

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    GpioCtrlRegs.GPBDIR.all = 0x0000000F;   // All outputs

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    EDIS;

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}


Empfangsseite:
1
 /*

2
 * This script is intended to wait for message on eCANA

3
 * Receiving message box address: 0xFF

4
 * */

5


6


7
#include "DSP28x_Project.h"     // Device Headerfile and Examples Include File

8
// Prototype statements for functions found within this file.

9
void delay();

10
void Gpio_select(void);

11
void ReceiveCANMsg(int16 MBXnum);

12


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// CAN

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#define CAN_RECEIVE_MAILBOX_ADDRESS 0xFF

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#define CAN_RECEIVER CAN_RECEIVE_MAILBOX_ADDRESS // test case

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#define CAN_BITS_SEND 4

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18


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void main(void)

21
{

22


23
  // eCAN control registers require read/write access using 32-bits.  Thus we

24
    // will create a set of shadow registers for this example.  These shadow

25
    // registers will be used to make sure the access is 32-bits and not 16.

26
    struct ECAN_REGS ECanaShadow;

27
    struct ECAN_MBOXES ECanMboxShadow;

28


29
    // Step 1. Initialize System Control:

30
    // PLL, WatchDog, enable Peripheral Clocks

31
    // This example function is found in the DSP2833x_SysCtrl.c file.

32
      InitSysCtrl();

33


34


35
  // Step 2. Initalize GPIO:

36
  // This example function is found in the DSP2833x_Gpio.c file and

37
  // illustrates how to set the GPIO to it's default state.

38
  // InitGpio();  // Skipped for this example

39


40
  Gpio_select(); // for LEDs

41
  InitECanaGpio(); //for CAN bus

42


43
// Step 3. Clear all interrupts and initialize PIE vector table:

44
// Disable CPU interrupts

45
  DINT;

46


47
// Initialize the PIE control registers to their default state.

48
// The default state is all PIE interrupts disabled and flags

49
// are cleared.

50
// This function is found in the DSP2833x_PieCtrl.c file.

51
  InitPieCtrl();

52


53
// Disable CPU interrupts and clear all CPU interrupt flags:

54
  IER = 0x0000;

55
  IFR = 0x0000;

56


57
// Initialize the PIE vector table with pointers to the shell Interrupt

58
// Service Routines (ISR).

59
// This will populate the entire table, even if the interrupt

60
// is not used in this example.  This is useful for debug purposes.

61
// The shell ISR routines are found in DSP2833x_DefaultIsr.c.

62
// This function is found in DSP2833x_PieVect.c.

63
  InitPieVectTable();

64


65
// Step 5. User specific code, enable interrupts

66
  // CAN

67
  InitECana(); // Initialize eCAN-A module

68


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  ECanaRegs.CANME.all = 0x00000000; // Disable all mailboxes

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   // Receiving MBOX2

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   ECanMboxShadow.MBOX2.MSGID.bit.AAM = 0;   // auto answer mode off

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   ECanMboxShadow.MBOX2.MSGID.bit.AME = 0;      // acceptance mask disable

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   ECanMboxShadow.MBOX2.MSGID.bit.IDE = 0;

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   ECanMboxShadow.MBOX2.MSGID.bit.STDMSGID = CAN_RECEIVE_MAILBOX_ADDRESS;

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   ECanaMboxes.MBOX2.MSGID.all = ECanMboxShadow.MBOX2.MSGID.all;

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   ECanaShadow.CANMD.all = ECanaRegs.CANMD.all;

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  ECanaShadow.CANMD.bit.MD2 = 1;    // Mailbox 2 : receiving mailbox

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  ECanaRegs.CANMD.all = ECanaShadow.CANMD.all;

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// Enable Mailboxes

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  ECanaShadow.CANME.all = ECanaRegs.CANME.all;

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    ECanaShadow.CANME.bit.ME2 = 1;

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  ECanaRegs.CANME.all = ECanaShadow.CANME.all;

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   ECanaMboxes.MBOX2.MSGCTRL.bit.DLC = CAN_BITS_SEND;

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   ECanaMboxes.MBOX2.MSGCTRL.bit.RTR = 0;

92


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   GpioDataRegs.GPBDAT.bit.GPIO34 = 1;//LED3 off

94


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// Step 6. IDLE loop. Just sit and loop forever (optional):

96
   for(;;)

97
   {

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       if (ECanaRegs.CANRMP.all > 0 && ECanaRegs.CANGIF0.bit.MIV0 == 2)

99
       {

100
           ReceiveCANMsg (2);

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       }

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   }

104


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}

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void ReceiveCANMsg(int16 MBXnum)

107
{

108
    volatile struct MBOX *srcMBox;

109
    Uint32 raw_datah;

110
    Uint32 raw_datal;

111


112
    if (0 <= MBXnum && MBXnum <= 32)

113
    {

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        // Get pointer to mailbox struct and grab data

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        srcMBox = &ECanaMboxes.MBOX0 + MBXnum;

116
        raw_datah = srcMBox->MDH.all;

117
        raw_datal = srcMBox->MDL.all;

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        ECanaRegs.CANRMP.all = (0x00000001 << MBXnum);

119


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        /* Process Data */

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        if(GpioDataRegs.GPBDAT.bit.GPIO34)

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          GpioDataRegs.GPBDAT.bit.GPIO34 = 0;//LED3 on

123
        else

124
           GpioDataRegs.GPBDAT.bit.GPIO34 = 1;//LED3 off

125
    }

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}

127


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void delay()

129
{

130
  double i;

131
  for (i = 0; i < 2000000; i++)

132
  {

133
  }

134


135
}

136
void Gpio_select(void)

137
{

138


139


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    EALLOW;

141
  GpioCtrlRegs.GPAMUX1.all = 0x00000000;  // All GPIO

142
  GpioCtrlRegs.GPAMUX2.all = 0x00000000;  // All GPIO

143
  GpioCtrlRegs.GPAMUX1.all = 0x00000000;  // All GPIO

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    GpioCtrlRegs.GPADIR.all = 0xFFFFFFFF;   // All outputs

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    GpioCtrlRegs.GPBDIR.all = 0x0000000F;   // All outputs

146
    EDIS;

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}


Was mache ich falsch, dass die Signale nicht auf der Empfangsseite 
ankommen? (Led blinkt nicht)

Vielen Dank und viele Grüße
Sebastian
Antwort Zitieren Bearbeiten Thread verschieben Thread sperren Anmeldepflicht aktivieren Anpinnen Thread löschen Thread mit anderem zusammenführen Beitrag melden
anonym Gast #3855437
Lesenswert?
• ▲
▼ 
Sebastian schrieb:
> Dazu habe ich von den beiden gleichen
> Microcontrollern die Pins 30 miteinander verbunden (CANTXA) und auch die
> Pins 31 von beiden (CANRXA). Zwichen diesen beiden Leitungen (nur ein
> paar Zentimeter lang) habe ich ein 68 Ohm Widerstand gebastelt (anstelle
> von 2 120 Ohm Wid. an den Enden).

Und da liegt das Problem. Da fehlt je noch ein Transceiver zwischen µC 
und CAN Bus.

Z.B. ein SN 65HVD231D

Schau mal in dessen Datenblatt nach, was der macht.

Und wenn du noch ein bisschen was über den CAN ließt, dann wirst du auch 
feststellen, dass der Bus nur aus High und Low Leitung (und Gnd) besteht 
und von Rx und Tx keine Rede ist.
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