Hi,

I'm trying to communicate with a sensor using I2C interface and I use the I2C Master (UDB) component in the PSoC creator 2.0 to do so.The reset is connected to '0' and the SDA, SCL connected to the sensor (slave) with pull-ups resistors. I used many times before I2C interface so I very familiar with the protocol. the problem is that this time I get a complete module with functions that from the datasheet I just can't understand how to make a simple reading from the slave's registers:

I need to access to the sensor's address and then access its registers using another address and then read the data and save it.

The protocol of the sensor interface is simple and standard:

Master|S|AD+W|        |RA|        |S|AD+R|        |          |NACK|P|

Slave  |  |            |ACK|      |ACK|  |           |ACK|DATA|           |  |

If someone can give me a simple code example for how to use the component's functions to make this all work I'll be very grateful...

Thanks,

Michael.

I do not have a code-example at hand, but from your protocoll I can see  (|AD-W| , |AD+R|) that you might try to modify the sllave's address to indicate a read or write operation. This is handled within the master-software, you just specify the slave's base address where you want to read from or write to.

You'll easily find an example when you right-click un your I2C-module in the schematic or in the component catalog and then click on "Find example Project" which will bring up a dialog where you select your device (PSoC 5). The example given is for an EZI2c-slave, but that will not matter for the master and for the addressing.

Hope that helps

Bob

Thanks Bob for the reply,

I looked at that example before but I don't see how to address the registers after I address the device. Unlike the EzI2C In my case I use a device with registers... I'ts possible to invent the wheel all over again by writing the codes from scratch but I think that must be an easy way to do that using the I2C component functions which I just don't see/understand them from the datasheet or the EzI2C example...

 It may be better if you can give us the part number or the specification of the slave devices? 

The slave's datasheet: http://invensense.com/mems/gyro/documents/PS-MPU-6000A.pdf see pages 36 to 39

In my case the slave's address is: 0x68

The slave's register map: invensense.com/mems/gyro/documents/RM-MPU-6000A.pdf

I need code example for reading/writing one of the data registers.

Thanks,

Michael H.

I do not have an example-code right at hand, but it is a two-liner.

Have a look at the datasheet of the I2C Master/Multimaster/Slave module, page 19.

Use the

I2C_MasterReadBuf(SlaveAdr,&DataBuffer,2, I2C_MODE_COMPLETE_XFER);

That's all.

 Bob

I2C_MasterWriteBuf(SlaveAdr,&RegisterNumber,1, I2C_MODE_NO_STOP);

The lines of the above code have gotten mangled, I suppose you can order them correctly again (Write first, then read).

Bob

Thanks Bob for the support,

After alot of trying (and failing) the following code works:

int32 i;

uint8 wrData[1], rdData[2]; // Put in the wrData[0] array the register address

volatile uint8 status;

I2C_Start();

status = I2C_MasterSendStart(MPU6050_ADD, I2C_WRITE_XFER_MODE);

if(status == I2C_MSTR_NO_ERROR) /* Check if transfer completed without errors */

{

/* Send array of 1 bytes */

for(i=0; i<1; i++)

{

status = I2C_MasterWriteByte(wrData[i]);

if(status != I2C_MSTR_NO_ERROR) break;

}

}

I2C_MasterSendStop(); /* Send Stop */

status = I2C_MasterSendStart(MPU6050_ADD, I2C_READ_XFER_MODE);

if(status == I2C_MSTR_NO_ERROR) /* Check if transfer completed without errors */

{

/* Read array of 2 bytes */

for(i=0; i<2; i++)

{

if(i < 1) rdData[i] = I2C_MasterReadByte(I2C_ACK_DATA);

else rdData[i] = I2C_MasterReadByte(I2C_NAK_DATA);

}

}

I2C_MasterSendStop(); /* Send Stop */

I2C_Stop();

Well, looks a bit more than my twoliner... But fine that you've got it and thank you to share your code with us!

Bob