TMS320F28375S: not able to read I2C data from AM4096 magnetic encoder.

Hello Muzammil,

Have you referred to the existing examples for I2C in C2000Ware? The example i2c_ex3_external_loopback shows how to use send/receive data with I2C and even has an interrupt for the I2C FIFO, I would recommend looking at it for your basic setup. Make sure you can run this example before proceeding, that way you have a known good starting point before development.

C2000Ware_5_01_00_00\driverlib\f2837xs\examples\cpu1\i2c

Hello Omer,

thanks for reply,

In my case, i have to get data from I2C in polling mode and without FIFO mode. for that i am trying but i am not able to get the data. please suggest me further.

I have also attached the code of how I am doing this in previous message. please provide me support related to this.

thanks and regards

Muzammil Qureshi

Hello omer,

The clock goes in low state after the first transmission.

thanks and regards

Muzammil Qureshi

Hello Muzammil,

Muzammil Qureshi said:

In my case, i have to get data from I2C in polling mode and without FIFO mode. for that i am trying but i am not able to get the data. please suggest me further.

In the example folder I mentioned earlier, there isn't an example without using the FIFO and polling, but i2c_ex4_eeprom_polling shows how to use I2C with polling. If you take a look at Figure 19-7. I2C Master TX / RX Flowchart in the I2C chapter of the reference manual, you can see that if you're not using FIFO or repeat mode then transmitting data only requires filling the I2CDXR register with the next data:

In driverlib, this means using the I2C_putData to fill the register.

Looking at your code, I'm not sure exactly what you're doing sending multiple starts without a stop. The flow diagram shows that transmitting data with/without FIFO only differs in the interrupt that would need to be polled. Are you trying to use repeat mode? If so, your I2CMDR register would not be configured correctly based on your I2C setup. It doesn't look like SysConfig has the option for repeat mode, so I'll let the software experts know to add this. In the meantime, you I2C_setConfig would need to include the I2C_REPEAT_MODE macro for using repeat mode, if that's what you intend.

Muzammil Qureshi said:

I have also attached the code of how I am doing this in previous message. please provide me support related to this.

You stated that your code wasn't working, so I was going to cite working examples to help simplify the solution rather than correcting your code.

Hello Omer,

Omer Amir said:

Looking at your code, I'm not sure exactly what you're doing sending multiple starts without a stop.

I have put start condition without stop condition because, after writing slave address and register address from which i have to read, i have to generate REPEATED START condition (which can be generated writing start condition without writing stop condition) to get the data as per the datasheet of AM4096.

the second thing is my SDA line always goes low after first transmission.

let me explain problem in detail.

I am getting the data only one time and that also after connecting AM4096 encoder to its own USB hardware (UPRGAM4096) and then again connecting to controller. first time i get data and the SDA line goes low. then again after connecting encoder to usb interface and reconnecting to controller, it gives only one data and again SDA line goes low.

while(1)
{
    while (I2C_isBusBusy(myI2C0_BASE));  // Ensure bus is not busy

    // Write operation

    I2C_setConfig(myI2C0_BASE, I2C_MASTER_SEND_MODE | I2C_REPEAT_MODE);
    I2C_setSlaveAddress(myI2C0_BASE, 90);  // 90 addr
    DEVICE_DELAY_US(30);
    I2C_setDataCount(myI2C0_BASE, 1);
    DEVICE_DELAY_US(30);
    I2C_putData(myI2C0_BASE, 0x20);  // Command/Register to read from
    DEVICE_DELAY_US(30);
    I2C_sendStartCondition(myI2C0_BASE);
    DEVICE_DELAY_US(30);
    while (!(I2C_getStatus(myI2C0_BASE) & I2C_STS_REG_ACCESS_RDY));
    DEVICE_DELAY_US(30);
//        DEVICE_DELAY_US(500);

    // Read operation
    I2C_setConfig(myI2C0_BASE, I2C_MASTER_RECEIVE_MODE | I2C_REPEAT_MODE);
    DEVICE_DELAY_US(30);
    I2C_setSlaveAddress(myI2C0_BASE, 90);
    DEVICE_DELAY_US(30);
    I2C_setDataCount(myI2C0_BASE, 2);  // Assuming you want to read 2 bytes
    DEVICE_DELAY_US(30);
    I2C_sendStartCondition(myI2C0_BASE);  // Repeated start for read operation
    DEVICE_DELAY_US(30);

    // Wait for data to be ready and read it
    for (i = 0; i < 2; i++) {
        while (!(I2C_getStatus(myI2C0_BASE) & I2C_STS_REG_ACCESS_RDY));
        I2C_buf[i] = I2C_getData(myI2C0_BASE);
        DEVICE_DELAY_US(30);
    }

    I2C_sendStopCondition(myI2C0_BASE);  // Stop condition
    DEVICE_DELAY_US(30);
}

Hello Muzammil,

Please provide a screenshot of the communication taking place and where the issue occurs. Can you also tell me what the values of the pullup resistors are on SDA/SCL?

Hello Omer,

Omer Amir said:

Please provide a screenshot of the communication taking place and where the issue occurs.

i get data first time. After the arrow marked by me, the SCL line always goes low. then I debug my project again and i see this.

 now, my SDA line goes low. this process occurs until i connect it ot UPRGAM4096 interface and reconnect to controller again.

i am attaching the screenshot of usb software interface.

Omer Amir said:

Can you also tell me what the values of the pullup resistors are on SDA/SCL?

I am using RMK4 eval board. here is the schematic.

I have set my pins as 'Open-drain output with pull-up enabled output and input' by sysconfig. 

i have already given my lots of time for I2C of my project, please help me with this.

thanks and regards

Muzammil Qureshi.