I2C-Kommunikationsproblem zwischen TI 28016 und Sensor BMA020

Stephan Gast #2109716
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Hallo.

Ich versuche seit einer Woche vergeblich die I2C-Kommunikation zwischen 
meinem TI 28016, welcher auf nem Olimex Development Board sitzt, und 
einem  BMA020 Beschleunigungssensor herzustellen. Laut Datenblatt zum 
Sensor sind dafür "nur" folgende Schritte notwendig:

- Befehl 0x02 an Adresse 0x70 (fixe Sensoradresse 0x38 plus RW=0) senden
- 6 Byte (Messergebnisse) von Adresse 0x71 (fixe Sensoradresse 0x38 plus 
RW=1) auslesen

Meine µC-Kenntnis sind eher rudimentär und  mit dem TI arbeite ich erst 
seit 3 Wochen. Deshalb habe ich versucht ein fertiges Snippet 
anzupassen, geschrieben von Brad Griffis 2008.
Das ist dabei rausgekommen:
1
//I2C test 

2


3
#include "DSP280x_Device.h"     // DSP280x Headerfile Include File

4
#include "DSP280x_Examples.h"   // DSP280x Examples Include File

5


6
// Prototype statements for functions found within this file.

7
void   I2CA_Init(void);

8
Uint16 I2C_Write(Uint16 slvaddr, int data, Uint16 length);

9
Uint16 I2C_Read(Uint16 slvaddr, Uint16* data, Uint16 length);

10


11
Uint16 Values[6];

12


13
void main(void)

14
{

15
   InitSysCtrl();  // Step 1. Initialize System Control:

16
   InitI2CGpio();  // Step 2. Initalize GPIO only for I2C functionality

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   I2CA_Init();    // Step 4. Initialize all the Device Peripherals

18


19
   for(;;)    // Application loop

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   {   

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     I2C_Write(0x70,0x02,2);

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     I2C_Read(0x71,Values,6);

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   }   // end of for(;;)

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}   // end of main

25


26


27
void I2CA_Init(void)

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{

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//   I2caRegs.I2CSAR = 0x38;    // Slave address - EEPROM control code

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   I2caRegs.I2CPSC.all = 6;    // Prescaler - need 7-12 Mhz on module clk for 60MHz CPU

31
   I2caRegs.I2CCLKL = 4200;    // NOTE: must be non zero

32
   I2caRegs.I2CCLKH = 4200;    // NOTE: must be non zero

33
   I2caRegs.I2CIER.all = 0x3E;    // Enable SCD,XRDY,RRDY,ARDY,NACK interrupts

34
//   I2caRegs.I2CMDR.all = 0x0020;  // Take I2C out of reset, Stop I2C when suspended

35
//   I2caRegs.I2CFFTX.all = 0x6000;  // Enable FIFO mode and TXFIFO

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//   I2caRegs.I2CFFRX.all = 0x2040;  // Enable RXFIFO, clear RXFFINT,

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   return;

38
}

39


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Uint16 I2C_Write(Uint16 slvaddr, int data, Uint16 length)

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{

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   Uint16 i;

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   while (( I2caRegs.I2CSTR.bit.BB==1 ));  //bus busy?

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   if (I2caRegs.I2CSTR.bit.BB == 1)

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   {

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      return I2C_BUS_BUSY_ERROR;

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   }

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  I2caRegs.I2CMDR.all = 0;  //disable I2C during config

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  I2caRegs.I2CCNT = length;  //number of bytes to be send

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  I2caRegs.I2CSAR = slvaddr;  //setup receiver addr

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//  Mode settings

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  I2caRegs.I2CMDR.bit.IRS=1;  //I2C module enable              

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  I2caRegs.I2CMDR.bit.STT=1;  //If master -> start condition generated

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  I2caRegs.I2CMDR.bit.STP=1;  //If master -> stop condition generated if data counter=0

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  I2caRegs.I2CMDR.bit.TRX=1;  //Transmitter mode

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  I2caRegs.I2CMDR.bit.MST=1;  //Master mode

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  I2caRegs.I2CMDR.bit.FREE=1;  //I2C module runs free

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  I2caRegs.I2CMDR.bit.RM=1;  

59
  

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  /* Transmission*/

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

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  {

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    while(!(I2caRegs.I2CSTR.bit.XRDY|I2caRegs.I2CSTR.bit.ARDY));  //wait for xdry flag before transmit data or ardy if NACK appears

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    if (I2caRegs.I2CSTR.bit.NACK==1)        //if NACK appears -> SCL=low, STP=0

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    {

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      I2caRegs.I2CMDR.all=0;          //reset I2C -> SCL not held low

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    }

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    I2caRegs.I2CDXR = data;

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  }

70
}

71


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Uint16 I2C_Read(Uint16 slvaddr, Uint16* data, Uint16 length)

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{

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  Uint16 i;

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  while (( I2caRegs.I2CSTR.bit.BB==1 ));    //bus busy?

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   if (I2caRegs.I2CSTR.bit.BB == 1)

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   {

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      return I2C_BUS_BUSY_ERROR;

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   }

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  I2caRegs.I2CMDR.all = 0;      //disable I2C during config

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  I2caRegs.I2CCNT = length;      //number of bytes to be send

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  I2caRegs.I2CSAR = slvaddr;      //setup receiver addr

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//  Mode settings

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  I2caRegs.I2CMDR.bit.IRS=1;      //I2C module enable              

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  I2caRegs.I2CMDR.bit.STT=1;      //If master -> start condition generated

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  I2caRegs.I2CMDR.bit.STP=1;      //If master -> stop condition generated if data counter = 0

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  I2caRegs.I2CMDR.bit.MST=1;      //Master mode

88
  I2caRegs.I2CMDR.bit.FREE=1;       //I2C module runs free

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  I2caRegs.I2CMDR.bit.NACKMOD=1;

90


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  /* Reception */

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

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  {

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    while(!(I2caRegs.I2CSTR.bit.XRDY|I2caRegs.I2CSTR.bit.ARDY));  //wait for xdry flag before transmit data or ardy if NACK appears

95
    if (I2caRegs.I2CSTR.bit.NACK==1)        //if NACK appears -> SCL=low, STP=0

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    {

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      I2caRegs.I2CMDR.all=0;          //reset I2C -> SCL not held low

98
    }

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    while(I2caRegs.I2CSTR.bit.RRDY==1);

100
    data[i] = I2caRegs.I2CDRR ;

101
  }

102
}

103


104
//EOF


Das Ergebnis hab ich mir mit nem Oszi angeschaut: Nach dem ersten Senden 
wird SDI auf low gezogen und SCK bleibt high. Wenn ich die
1
while (( I2caRegs.I2CSTR.bit.BB==1 ));

in der Schreib- bzw. Lesefunktion auskommentiere kann ich folgendes Bild 
sehen:

http://img24.imageshack.us/img24/7899/bild0027h.jpg

Meiner laienhaften Meinung nach wird keine Stop Condition erzeugt, 
weshalb BB immer 1 ist. Obwohl ich dachte dass ich das mit setzen von 
STP eingestellt hab.

Ein Versuch eine I2C-Minimalversion für diese Sache zu schreiben sah so 
aus:
1
//I2C test 

2


3


4
#include "DSP280x_Device.h"     // DSP280x Headerfile Include File

5
#include "DSP280x_Examples.h"   // DSP280x Examples Include File

6


7
// Prototype statements for functions found within this file.

8
void   I2CA_Init(void);

9


10
Uint16 Values[6],i;

11


12


13
void main(void)

14
{

15
   InitSysCtrl();      // Step 1. Initialize System Control:

16
   InitI2CGpio();      // Step 2. Initalize GPIO only for I2C functionality

17
   I2CA_Init();        // Step 4. Initialize all the Device Peripherals:

18


19


20
   for(;;)          // Application loop

21
   {

22
             //---> Write instruction <--- //

23
      I2caRegs.I2CMDR.bit.STT = 1;

24
      I2caRegs.I2CSAR = 0x70;        //Write addr

25
      I2caRegs.I2CCNT = 3;        //3bytes=2bytes addr + 1 byte instr

26
      I2caRegs.I2CDXR = 0x02;        //instr

27
      I2caRegs.I2CMDR.bit.STP = 1; 

28
//      I2caRegs.I2CMDR.all = 0x2620;    //Send data to setup EEPROM address

29


30
      

31
      //---> Read values <--- //

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      I2caRegs.I2CMDR.bit.STT = 1;

33
      I2caRegs.I2CSAR = 0x71;        //Read addr

34
      I2caRegs.I2CCNT = 1;        //6bytes=2bytes per coordinate

35
      Values[0] = I2caRegs.I2CDRR;

36
      /*for(i=0;i<6;i++)

37
      {

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        Values[i] = I2caRegs.I2CDRR;

39
      }*/

40
      I2caRegs.I2CMDR.all = 0x2C20;      //Send restart as master receiver

41
       I2caRegs.I2CMDR.bit.STP = 1;          

42
   }   // end of for(;;)

43
}   // end of main

44


45


46
void I2CA_Init(void)

47
{

48
//   I2caRegs.I2CSAR = 0x38;      // Slave address - EEPROM control code

49
   I2caRegs.I2CPSC.all = 6;      // Prescaler - need 7-12 Mhz on module clk for 60MHz CPU

50
   I2caRegs.I2CCLKL = 4200;      // NOTE: must be non zero

51
   I2caRegs.I2CCLKH = 4200;      // NOTE: must be non zero

52
   I2caRegs.I2CIER.all = 0x24;    // Enable SCD & ARDY interrupts

53
   I2caRegs.I2CMDR.all = 0x0020;  // Take I2C out of reset, Stop I2C when suspended

54
   I2caRegs.I2CFFTX.all = 0x6000;  // Enable FIFO mode and TXFIFO

55
   I2caRegs.I2CFFRX.all = 0x2040;  // Enable RXFIFO, clear RXFFINT,

56
   return;

57
}

58


59
//EOF

Führte aber leider auch nicht zum Ergebnis.

Falls jemand hier Erfahrungen mit TI DSPs/I2C oder Vorschläge jeglicher 
Art zu meinen beiden Code-Versuchen hat wäre ich sehr dankbar.

Grüße
Stephan
Antwort Zitieren Bearbeiten Thread verschieben Thread sperren Anmeldepflicht aktivieren Anpinnen Thread löschen Thread mit anderem zusammenführen Beitrag melden
Stephan Gast #2115783
Lesenswert?
• ▲
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habs jetzt hinbekommen und falls mal jemand den BMA020 mit TI C2000 DSPs 
nutzen will poste ich mal meinen, durchaus verbesserungswürdigen, Code, 
welcher im Roboternetz gepostete Codeschnipsel enthält.

1
//I2C test 

2


3
#include "DSP280x_Device.h"     // DSP280x Headerfile Include File

4
#include "DSP280x_Examples.h"   // DSP280x Examples Include File

5


6
// Prototype statements for functions found within this file.

7
void   I2CA_Init(void);

8


9
int Values[6]={0,0,0,0,0,0};

10
Uint16 instr=0x02;

11
int i,dx=0,dy=0,dz=0;

12
double D2G,gx=0,gy=0,gz=0;

13


14
void main(void)

15
{

16
   InitSysCtrl();      // Step 1. Initialize System Control:

17
   InitI2CGpio();      // Step 2. Initalize GPIO only for I2C functionality

18
   I2CA_Init();        // Step 4. Initialize all the Device Peripherals

19
   

20
   D2G=0.00390625;      // 4g/1024

21
   

22
   for(;;)          // Application loop

23
     {  

24
       I2caRegs.I2CSAR = 0x38;             //Set slave address

25
       I2caRegs.I2CCNT = 1;             //Set count to 5 characters plus 2 address bytes

26
       I2caRegs.I2CDXR = 0x02;            //Send eeprom high address            

27
       I2caRegs.I2CMDR.bit.TRX = 1;         //Set to Transmit mode

28
       I2caRegs.I2CMDR.bit.MST = 1;         //Set to Master mode

29
       I2caRegs.I2CMDR.bit.FREE = 1;        //Run in FREE mode

30
       I2caRegs.I2CMDR.bit.STP = 1;         //Stop when internal counter becomes 0

31
       I2caRegs.I2CMDR.bit.STT = 1;         //Send the start bit, transmission will follow

32
        

33
    

34
       while(I2caRegs.I2CSTR.bit.XRDY == 0){};     //Do nothing till data is shifted out

35
       I2caRegs.I2CCNT = 6;              //read 6 bytes from eeprom

36
       I2caRegs.I2CMDR.bit.TRX = 0;         //Set to Recieve mode

37
       I2caRegs.I2CMDR.bit.MST = 1;         //Set to Master mode

38
       I2caRegs.I2CMDR.bit.FREE = 1;        //Run in FREE mode

39
       I2caRegs.I2CMDR.bit.STP = 1;         //Stop when internal counter becomes 0

40
       I2caRegs.I2CMDR.bit.STT = 1;         //Repeated start, Reception will follow

41
       for(i = 0; i < 6; i++)

42
         {

43
           while(I2caRegs.I2CSTR.bit.RRDY == 0){};   //I2CDRR not ready to read?

44
           Values[i] = I2caRegs.I2CDRR;

45
         }

46
       DELAY_US(100);                //wait for new data provided

47
       dx=Values[0];                //dataadaptation by malthy & Sternthaler

48
       dx=(dx|((Values[1]<<8))>>6);

49
       gx=dx*D2G;

50
       dy=Values[2];

51
       dy=(dx|((Values[3]<<8))>>6);

52
       gy=dy*D2G;

53
    dz=Values[4];

54
       dz=(dx|((Values[5]<<8))>>6);

55
       gz=dz*D2G;

56
                         

57
   }   // end of for(;;)

58
}   // end of main

59


60


61
void I2CA_Init(void)

62
{

63
   I2caRegs.I2CSAR = 0x38;      // Slave address - EEPROM control code

64
   I2caRegs.I2CPSC.all = 6;      // Prescaler - need 7-12 Mhz on module clk for 60MHz CPU

65
   I2caRegs.I2CCLKL = 42;      // NOTE: must be non zero

66
   I2caRegs.I2CCLKH = 21;      // NOTE: must be non zero

67
   I2caRegs.I2CIER.all = 0x3E;    // Enable SCD,XRDY,RRDY,ARDY,NACK interrupts

68
   I2caRegs.I2CMDR.bit.IRS = 1;    // Take I2C out of reset, Stop I2C when suspended

69
   I2caRegs.I2CFFTX.all = 0x0000;  // Enable FIFO mode and TXFIFO

70
   I2caRegs.I2CFFRX.all = 0x0000;  // Enable RXFIFO, clear RXFFINT,

71
   return;

72
}

73


74
//EOF


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