STM32 I2C problem

sukrubahadirarslan · ‎2013-12-18

Posted on December 18, 2013 at 19:46

hello.

I want to communicate with sensör with I2C.

First I must send the sensor register address to sensor.

And then I receive the data from this sensor register.

So first I configure I2C peripheral as master transmitter.

Can I change the master transmitter to master receiver without generating stop condition ?

I mean, I write this code :

I2C_GenerateSTART(I2C1,ENABLE);

I2C_GetFlagStatus(I2C1,I2C_FLAG_SB);

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_MSL)==RESET);

I2C_Send7bitAddress(I2C1,MPU6050_Default_Address,I2C_Direction_Transmitter);

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_TRA)==RESET);

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_ADDR)==RESET);

I2C_GetFlagStatus(I2C1,I2C_FLAG_ADDR);

I2C_GetFlagStatus(I2C1,I2C_FLAG_MSL); // read sr2 . clear ADDR bit.

I2C_SendData(I2C1,Gyrox_Data_MSB8_Register_Address);

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_TXE)==RESET);

// Should I generate a STOP condition here ? or Can I resume like this ? :

I2C_GenerateSTART(MPU6050_I2C, ENABLE);

I2C_Send7bitAddress(MPU6050_I2C, slaveAddr, I2C_Direction_Receiver);

...

thanks for your help

chen · ‎2013-12-19

Posted on December 19, 2013 at 10:56

Hi

I am not going to debug you code.

''Can I change the master transmitter to master receiver without generating stop condition ?''

Yes.

It is called a 'repeated start condition'.

The full I2C spoecification :

Sadly, it is long winded and goes on about lots of stuff (like ultra high speed) that is not relevant to you.

There are loads of information about I2C on the WEB.

sukrubahadirarslan · ‎2013-12-20

Posted on December 20, 2013 at 14:36

Thanks a lot.

this document is very good.

I have one more different question.

I read in datasheet that : I must clearADDR bit after address transmission.

In this code I monitor ADDR bit like this :

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_ADDR)==RESET);

When ADDR bit is set , ADDR bit is clear in this line ? or

Should I write this code like this for clearing the ADDR bit ?

while(I2C_GetFlagStatus(I2C1,I2C_FLAG_ADDR)==RESET);

I2C_GetFlagStatus(I2C1,I2C_FLAG_ADDR) ----> t

his line is required ???

sorry about my english .

thanks again.