I2C Communication with ADXL345 Accelerometer

Stelios Gan

Other Parts Discussed in Thread: HALCOGEN

Hello people,

I am trying to communicate with the ADXL345 accelerometer via I2C with the generated drivers from HalCoGen. It looks that I am currently sending correctly the data to the SDA line, but I cannot receive anything.

The frame for this device for I2C must be as follows:

My first step is to read the device id (should read 0xE5).

The slave address is 0x53, which interprets to 0xA6 for write, 0xA7 for read.
The register to get the device id is 0x00.

The screenshot of my logic analyzer currently is:

I assume it looks good for sending.

My problem is that I cannot receive anything.

I tried to keep my code as simple as possible:

	i2cInit();

	/* Configure address of Slave to talk to */
	i2cSetSlaveAdd(i2cREG1, 0x53);

	/* Set mode as Master */
	i2cSetMode(i2cREG1, I2C_MASTER);

	/* Transmit Start Condition */
	i2cSetStart(i2cREG1);

	/* Tranmit 3 bytes of data in Polling mode */
	i2cSend(i2cREG1, 3, TX_Data_Master);

	i2cSetDirection(i2cREG1, I2C_RECEIVER);

	i2cSetStart(i2cREG1);

	i2cReceive(i2cREG1, 1, RX_Data_Master);


	while(1);

In any case I attach my whole project. I would be grateful for any suggestions.

3632.I2C.zip

Kind regards,
Stelios

over 9 years ago

0 QJ Wang over 9 years ago

TI__Guru**** 191596 points

Hi Stelios,

I will read your code, then come back to you later.

regards,
QJ

0 Stelios Gan over 9 years ago in reply to QJ Wang

Intellectual 450 points

Hello QJ,

Just an update:

I noticed that my 3rd byte should be preceded by a new Start condition. I tried to setStart again, but no luck. By the way, the option "Enable Repeat Mode", is for consecutive sends (i.e i2cSendByte, i2cSendByte, ...)?

I am looking forward for your suggestions.

Kind regards,
Stelios

0 Stelios Gan over 9 years ago in reply to QJ Wang

Intellectual 450 points

QJ,

Any updates?

0 Stelios Gan over 9 years ago in reply to Stelios Gan

Intellectual 450 points

Hello,

I am still struggling with it if anyone is wondering.

with the following code it is working:

void main(void)
{
/* USER CODE BEGIN (3) */
	sint16 x,y,z=0;
	uint8 data_in[10];
	int i;
	i2cInit();
	i2cSetSlaveAdd(i2cREG1, ADXL345Addr);


  while(1)
  {

	i2cSetCount(i2cREG1, 1);
	i2cREG1->MDR = i2cREG1->MDR | I2C_MASTER | I2C_TRANSMITTER;
	i2cSetStart(i2cREG1);
	i2cSendByte(i2cREG1, 0x00);													// Read address
	for (i=0;i<10000;i++);

	i2cSetCount(i2cREG1, 1);
	i2cREG1->MDR =  I2C_START_COND | I2C_STOP_COND |I2C_MASTER | I2C_RECEIVER | I2C_RESET_OUT;
	i2cReceive(i2cREG1,1,data_in);
	for (i=0;i<10000;i++);


	i2cSetCount(i2cREG1, 2);
	i2cREG1->MDR = i2cREG1->MDR | I2C_MASTER | I2C_TRANSMITTER;
	i2cSetStart(i2cREG1);
	i2cSendByte(i2cREG1, 0x31);													// Read address
	i2cSendByte(i2cREG1, 0x01);													// Read address
	for (i=0;i<10000;i++);

	i2cSetCount(i2cREG1, 2);
	i2cREG1->MDR = i2cREG1->MDR | I2C_MASTER | I2C_TRANSMITTER;
	i2cSetStart(i2cREG1);
	i2cSendByte(i2cREG1, 0x2D);													// Read address
	i2cSendByte(i2cREG1, 0x08);													// Read address
	for (i=0;i<10000;i++);


	i2cSetCount(i2cREG1, 1);
	i2cREG1->MDR = i2cREG1->MDR | I2C_MASTER | I2C_TRANSMITTER;
	i2cSetStart(i2cREG1);
	i2cSendByte(i2cREG1, 0x32);													// Read address												// Read address
	for (i=0;i<10000;i++);


	i2cSetCount(i2cREG1, 6);
	i2cREG1->MDR =  I2C_START_COND | I2C_STOP_COND |I2C_MASTER | I2C_RECEIVER | I2C_RESET_OUT;
	i2cReceive(i2cREG1,6,data_in);
	for (i=0;i<10000;i++);

	x = (sint8) data_in[1] << 8 | (sint8) data_in[0];
	y = (sint8) data_in[3] << 8 | (sint8) data_in[2];
	z = (sint8) data_in[5] << 8 | (sint8) data_in[4];
	printf("x = %d, y = %d, z = %d \n", x, y, z );



  }


/* USER CODE END */
}

and I get the right results. If I remove the for loops between the send and receive it waits in the line "while ((i2c->STR & (uint32)I2C_RX_INT) == 0U)".

Any suggestions now??? I would be really grateful.

Kind regards,
Stelios

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I2C Communication with ADXL345 Accelerometer