Forum: Mikrocontroller und Digitale Elektronik dsPIC33EV ECAN-DMA Problem


dsPIC33EV ECAN-DMA Problem
von Robin (Gast)

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Hallo Leute,

ich arbeite jetzt schon ein paar tage an der Realisierung eines CAN 
Moduls mit dem dsPIC33EV32GM102 als Controller und einem MCP2551 als CAN 
Transceiver. Als zweiten Knoten auf dem Bus benutze ich ein MCP2515 Demo 
Board von Microchip. Nun zu meinem Problem. Leider funktioniert die CAN 
Kommunikation weder aus- noch eingehend. Ich habe viele der verfügbaren 
Beispielcodes implementiert, leider ohne Erfolg. Ich habe auch noch 
nicht ganz verstanden wie die Datenübertragung per DMA und das ECAN 
Peripherie-Modul sich gegenseitig triggern. So weit ich es verstanden 
habe, setzte ich das Bit für einen Message Transmit Request. Dieser löst 
einen Interrupt aus (der nicht aktiviert sein darf, so dass er vom DMA 
Controller abgearbeitet wird). Der DMA Controller beginnt dann die Daten 
aus dem RAM in den Transmit Buffer des CAN Moduls zu kopieren und löst 
nach Beenden des Vorgangs den DMA Interrupt aus. So weit ich verstehe 
mü+sste das CAN Modul dann automatisch die Daten an den Transceiver 
weiterreichen.

Mein CAN Bus ist für 125kbits/s konfiguriert und mein Controller läuft 
auf 35MHz. Sowohl Standard Messages, als auch Extended Messages werden 
unterstützt.

Empfangen werden sollen diverse verschiedene Adressen, deshalb sind so 
viele Filter konfiguriert.

Ich bin für jede Hilfe sehr dankbar!

Wünsche ein schönes Wochenende!

Robin

Hier mal noch der relevante Code:
Oscillator Konfiguration:
1
 

2
CLKDIVbits.PLLPRE = 0b0000; //Quartz oscillator frequency is divided by 2

3
    PLLFBDbits.PLLDIV = 0b000100001; //PLL feedback divides F_PLL by 35

4
    CLKDIVbits.PLLPOST = 0b01; //Further divides by 4 -> F_osc = 35MHz

5
    

6
    //built in unlock sequence for OSCCON high byte

7
    __builtin_write_OSCCONH(0x03); //New clock source is 0b011 (Primary Oscillator with PLL)

8
    

9
    //iniiate clock switching

10
    __builtin_write_OSCCONL(OSCCON | 0x01);

11
    

12
    // Wait for Clock switch to occur

13
    while (OSCCONbits.COSC!= 0b011);

14
    

15
    // Wait for PLL to lock

16
    while (OSCCONbits.LOCK!= 1);



Anlegen der Buffer:
1
 #define NUM_OF_ECAN_BUFFERS 16

2
3
4
__eds__ unsigned int canbuf[NUM_OF_ECAN_BUFFERS][8] 

5
__attribute__((eds,aligned(NUM_OF_ECAN_BUFFERS * 16))); //16 buffers with 8 words each (256 byte)



Relevanter Ausschnitt aus der Initialisierung:
1
//CAN

2
    C1CTRL1bits.REQOP = 0b100; //Switch to configuration mode

3
    while(C1CTRL1bits.OPMODE != 0b100); //Wait for operation mode to change

4
    

5
    C1CTRL1bits.WIN = 1; //filter window

6
    C1CTRL1bits.CSIDL = 0; //CAN module continues operation in device IDLE

7
    C1CTRL1bits.CANCKS = 0; //F_CAN is equal to F_P=17,5MHz

8
    C1CFG1bits.BRP = 0b000111; //T_Q is 2x7x1/F_CAN= 800ns 

9
    C1CFG1bits.SJW = 0b00; //SJW is 1T_Q

10
    C1CFG2bits.PRSEG = 0b100; //Prop segment is 3T_Q

11
    C1CFG2bits.SEG1PH = 0b100; //Segment 1 is 3T_Q

12
    C1CFG2bits.SEG2PH = 0b100; //Segment 2 is 3T_Q

13
    C1CFG2bits.SEG2PHTS = 0; 

14
    C1CFG2bits.SAM = 1; //Bus line is sampled three times per sample point

15
    C1CFG2bits.WAKFIL = 0; //CAN bus line filter is used for wake up

16
    C1FEN1 = 0x3FFF; //Enable Filter 0:13

17
    C1BUFPNT1 = 0xFFFF; //messages are received in FIFO buffer

18
    C1BUFPNT2 = 0xFFFF;

19
    C1BUFPNT3 = 0xFFFF;

20
    C1BUFPNT4 = 0x00FF;

21
    

22
    C1RXF0SIDbits.SID = 0b00000000001; //Filter 0

23
    C1RXF0SIDbits.EID = 0b00; //Filter 0 (Extended Identifier)

24
    C1RXF0EID = 0x0000; //Filter 0 (Extended Identifier)

25
    C1RXF1SIDbits.SID = 0b00000000010; //Filter 1

26
    C1RXF1SIDbits.EID = 0b00; //Filter 1 (Extended Identifier)

27
    C1RXF1EID = 0x0000; //Filter 1 (Extended Identifier)

28
    C1RXF2SIDbits.SID = 0b00000000011; //Filter 2

29
    C1RXF2SIDbits.EID = 0b00; //Filter 2 (Extended Identifier)

30
    C1RXF2EID = 0x0000; //Filter 2 (Extended Identifier)

31
    C1RXF3SIDbits.SID = 0b00000000100; //Filter 3

32
    C1RXF3SIDbits.EID = 0b00; //Filter 3 (Extended Identifier)

33
    C1RXF3EID = 0x0000; //Filter 3 (Extended Identifier)

34
    C1RXF4SIDbits.SID = 0b00000000101; //Filter 4

35
    C1RXF4SIDbits.EID = 0b00; //Filter 4 (Extended Identifier)

36
    C1RXF4EID = 0x0000; //Filter 4 (Extended Identifier)

37
    C1RXF5SIDbits.SID = 0b00000000110; //Filter 5

38
    C1RXF5SIDbits.EID = 0b00; //Filter 5 (Extended Identifier)

39
    C1RXF5EID = 0x0000; //Filter 5 (Extended Identifier)

40
    C1RXF6SIDbits.SID = 0b00000000111; //Filter 6

41
    C1RXF6SIDbits.EID = 0b00; //Filter 6 (Extended Identifier)

42
    C1RXF6EID = 0x0000; //Filter 6 (Extended Identifier)

43
    C1RXF7SIDbits.SID = 0b00000001000; //Filter 7

44
    C1RXF7SIDbits.EID = 0b00; //Filter 7 (Extended Identifier)

45
    C1RXF7EID = 0x0000; //Filter 7 (Extended Identifier)

46
    C1RXF8SIDbits.SID = 0b00000001001; //Filter 8

47
    C1RXF8SIDbits.EID = 0b00; //Filter 8 (Extended Identifier)

48
    C1RXF8EID = 0x0000; //Filter 8 (Extended Identifier)

49
    C1RXF9SIDbits.SID = 0b00000001010; //Filter 9

50
    C1RXF9SIDbits.EID = 0b00; //Filter 9 (Extended Identifier)

51
    C1RXF9EID = 0x0000; //Filter 9 (Extended Identifier)

52
    C1RXF10SIDbits.SID = 0b0000001011; //Filter 10

53
    C1RXF10SIDbits.EID = 0b00; //Filter 10 (Extended Identifier)

54
    C1RXF10EID = 0x0000; //Filter 10 (Extended Identifier)

55
    C1RXF11SIDbits.SID = 0b00000001100; //Filter 11

56
    C1RXF11SIDbits.EID = 0b00; //Filter 11 (Extended Identifier)

57
    C1RXF11EID = 0x0000; //Filter 11 (Extended Identifier)

58
    C1RXF12SIDbits.SID = 0b00000001101; //Filter 12

59
    C1RXF12SIDbits.EID = 0b00; //Filter 12

60
    C1RXF12EID = 0x0000; //Filter 12

61
    C1RXF13SIDbits.SID = 0b00000001110; //Filter 13

62
    C1RXF13SIDbits.EID = 0b00; //Filter 13 (Extended Identifier)

63
    C1RXF13EID = 0x0000; //Filter 13 (Extended Identifier)

64
    

65
    C1FMSKSEL1 = 0x0000; //Mask0 determines the acceptance mask for all used filters

66
    C1FMSKSEL2 = 0x0000;

67
    C1RXM0SID = 0xFFF7; //All identifier digits are relevant, standard fames and extended frames are receivable

68
    C1RXM0EID = 0xFFFF;

69
    

70
    C1CTRL1bits.WIN = 0; //buffer window   

71
    C1FCTRLbits.DMABS = 0b100; //16 DMA buffers in RAM

72
    C1FCTRLbits.FSA = 0b00001; // FIFO area from TRB1 to RB15

73
    C1TR01CONbits.TXEN0 = 1; //Set TRB0 as transmit buffer

74
    IEC4bits.C1TXIE = 0; //deactivate interrpt processing by CPU

75
    IEC2bits.C1RXIE = 0;

76
    

77
    //DMA

78
    DMA0CONbits.AMODE = 0b10; //Peripheral indirect mode

79
    DMA0REQbits.IRQSEL = 0b00100010; //Connect to CAN RX peripheral

80
    DMA0PAD = (volatile unsigned int) &C1RXD; //Read from CAN1 RX register (address) 

81
    IEC0bits.DMA0IE = 1; //Enable interrupt for DMA channel 0

82
    DMA0CNT = 7; //8 words to be transmitted

83
    DMA1CONbits.AMODE = 0b10; //Peripheral indirect mode

84
    DMA1CONbits.DIR = 1; //Channel 1 reads data from RAM to CAN

85
    DMA1REQbits.IRQSEL = 0b01000110; //Connect to CAN TX peripheral

86
    DMA1PAD = (volatile unsigned int) &C1TXD; //Writes to CAN1 TX register (address)

87
    IEC0bits.DMA1IE = 1; //Enable interrupt for DMA channel 1

88
    DMA1CNT = 7; //8 words to be transmitted

89
    

90
    DMA0STAL = (unsigned int) &canbuf; //CAN receive FIFO buffer (16 buffer, 8 words each)

91
    DMA0STAH = 0x0000;

92
    DMA1STAL = (unsigned int) &canbuf;

93
    DMA1STAH = 0x0000;

94
    

95
    DMA0CONbits.CHEN = 1; //Enable DMA channel 0 for CAN RX

96
    DMA1CONbits.CHEN = 1; //Enable DMA channel 1 for CAN TX

97
    

98
    C1CTRL1bits.REQOP = 0b000; //Switch to normal CAN operation mode

99
    while(C1CTRL1bits.OPMODE != 0b000); //Wait for opeation mode to change

100
    

101
    //MUST be last operation here

102
    IFS1bits.CNIF = 0; //Reset all used interrupt flags

103
    IFS0bits.DMA0IF = 0;

104
    IFS0bits.DMA1IF = 0;

105
    IFS0bits.T1IF = 0;

106
    IFS2bits.C1RXIF = 0;

107
    IFS4bits.C1TXIF = 0;

108
    INTCON2bits.GIE = 1; //Global interrupt enable



Die Funktion die Nachrichten versendet:
1
bool SendMessage(uint16_t data_bytes[])

2
{

3
    /*      CAN data frame                                                     *

4
     *                                                                         *

5
     * Word 0:                                                                 *

6
     * bit 13-15    unimplemented                                              *

7
     * bit 2-12     Standard Identifier (SID)                                  *

8
     * bit 1        SRR - Substitute Remote Request bit                        *

9
     *              0 (normal message) - 1 (request remote message)            *

10
     *              MUST be 1 for extended message format                      *

11
     * bit 0        IDE bit - Identifier Extension bit                         *

12
     *              0 (standard message format) - 1 (extended message format)  *

13
     *                                                                         *

14
     * Word 1:                                                                 *

15
     * bit 12-15    unimplemented                                              *

16
     * bit 0-11     Extended Identifier (EID)                                  *

17
     *                                                                         *

18
     * Word 2:                                                                 *

19
     * bit 10-15    Extended Identifier (EID)                                  *

20
     * bit 9        Remote Transmission Request (RTR)                          *

21
     *              0 (normal message) - 1 (request remote transmission)       *

22
     *              IGNORED for standard message format                        *

23
     * bit 8        RB1 bit - MUST be set to 0                                 *

24
     * bit 5-7      unimplemented                                              *

25
     * bit 4        RB0 - MUST be set to 0                                     *

26
     * bit 0-3      Data Length Code - Numnber of bytes to send                * 

27
     *                                                                         *

28
     * Word 3:                                                                 *

29
     * bit 8-15     message byte 1                                             *

30
     * bit 0-7      message byte 0                                             *       

31
     *                                                                         *

32
     * Word 4:                                                                 *

33
     * bit 8-15     message byte 3                                             *

34
     * bit 0-7      message byte 2                                             *       

35
     *                                                                         *

36
     * Word 5:                                                                 *

37
     * bit 8-15     message byte 5                                             *

38
     * bit 0-7      message byte 4                                             *       

39
     *                                                                         *

40
     * Word 6:                                                                 *

41
     * bit 8-15     message byte 7                                             *

42
     * bit 0-7      message byte 6                                             *       

43
     *                                                                         *

44
     * Word 7:                                                                 *

45
     * bit 0-15     unimplemented                                              *      

46
     *                                                                        */

47
    

48
    

49
    unsigned int i, k, n;

50
    unsigned int j = 0;

51
    unsigned int number_of_bytes = sizeof(data_bytes)+1;

52
    

53
    n = (number_of_bytes/8)+1; //determine how many messages are needed

54
    if(number_of_bytes % 8 == 0) n--;

55
    for(k=0;k<n;k++) //send n messages 

56
    {

57
        for(i=0;i<8;i++) canbuf[0][i] = 0; //reset send buffer

58
59
        //save message to buffer

60
        canbuf[0][0] = (SID_OF_MAIN_CONTROLLER << 2) | 0x0003; //SID and send extended message 

61
        canbuf[0][1] = 0x000; //write EID

62
        if((number_of_bytes - k*8) <= 8) canbuf[0][2] = number_of_bytes;

63
        else canbuf[0][2] = 0x0008; //number of bytes to send

64
    

65
        if(canbuf[0][2] % 2 != 0) //if odd number of bytes to send write highest one out of normal flow

66
        {

67
            canbuf[0][3+(canbuf[0][2]/2)] = data_bytes[number_of_bytes - 1];

68
        }

69
        

70
        for(i=0;i<(canbuf[0][2]/2);i++)

71
        {

72
            canbuf[0][i+3] = data_bytes[j+1] << 8; //place upper byte

73
            canbuf[0][i+3] = canbuf[0][i+3] | (data_bytes[j] & 0x00FF); //place lower byte  

74
            j = j+2;

75
        }

76
        

77
        C1TR01CONbits.TXREQ0 = 1; //request message sending

78
    

79
        while(C1TR01CONbits.TXREQ0 == 1 && C1ECbits.TERRCNT == 0); //wait for transmission

80
        if(C1TR01CONbits.TXABT0 != 0 || C1ECbits.TERRCNT != 0)

81
        {

82
            C1ECbits.TERRCNT = 0;

83
            C1TR01CONbits.TXABT0 = 0;

84
            return false;

85
        }

86
    }

87
    

88
    return true; //messages sent without errors

89
}


Und zu guter Letzt die relevanten ISRs:
1
void __attribute__((interrupt, no_auto_psv)) _DMA0Interrupt(void)

2
{

3
    if(DMAPWCbits.PWCOL0 == 1) //write collision detect

4
    {

5
        DMAPWCbits.PWCOL0 = 0; //clear write collison bit

6
    }

7
    

8
    else if(DMARQCbits.RQCOL0 == 1) //user force and interrupt based collision detect

9
    {

10
        DMARQCbits.RQCOL0 == 0; //clear error bit

11
    }

12
    

13
    else if(C1RXOVF1 != 0) //tried to write to already full FIFO buffer

14
    {

15
        C1RXOVF1 = 0; //reset overflow flag

16
    }

17
    

18
    else if(C1ECbits.RERRCNT != 0) //receive error bit counter

19
    {

20
        C1ECbits.RERRCNT = 0; //reset counter

21
    }

22
    

23
    else //message received correctly

24
    {

25
        canmsg = true;

26
        

27
    }

28
    

29
    IFS0bits.DMA0IF = 0; // Clear the DMA0 Interrupt Flag 

30
    return;

31
}

32
33
void __attribute__((interrupt, no_auto_psv)) _DMA1Interrupt(void)

34
{

35
    IFS0bits.DMA1IF = 0;

36
    return;

37
}


  


  




  

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    Re: dsPIC33EV ECAN-DMA Problem
  


  

    

      von
      
        Robin (Gast)
      
      


      
    


    

      
    

    

    

  
  


  

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Ich habe noch die Konfiguaration des Input und Output Mappings 
vergessen:

1
//PORTB

2
    ANSELB = 0x0000; //Port B is all digital

3
    TRISB = 0b0000111111100100; //RB15:12 are outputs, RB11:5 are inputs, RB4:3 are outputs, RB2 is input, RB1:0 are outputs

4
    CNPUB = 0b0000111110000000; //Enable internal pull-up resistors on RB11:7

5
    CNENBbits.CNIEB1 = 1; //Enable Change of State interrupt for RB1

6
    CNENBbits.CNIEB11 = 1; //Enable Change of State interrupt for RB11 (when output module is changed ID4 bit always changes)

7
    IEC1bits.CNIE = 1; //globally enable change of state interrupt

8
    RPINR26bits.C1RXR = 0b0100010; //CAN1 RX tied to RPI34

9
    RPOR0bits.RP35R = 0b001110; //CAN1 TX tied to RP35    

10
    LATBbits.LATB4 = 0; //Disable digital output


  


  




  

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