TMS320F2800137: MCP79410 RTC interfacing issue with TMS320F2800137 over I2C - No SDA activity

Tool/software:

Hello TI Community,

I am trying to interface the MCP79410 RTC IC with the TMS320F2800137 microcontroller using the I2C communication protocol. I am using I2C pins of the MCU for this connection. However, I am not seeing any data activity on the SDA line, and the communication does not seem to be taking place.

Here’s what I’ve done:

Connected the SCL and SDA lines with 4.7k pull-up resistors.

Configured I2C in master-transmitter mode.

Verified pin muxing for the I2C lines.

The MCP79410 address is 0x6F as per the datasheet.

Here’s what I’ve done:                                                                                                                                                                                                                                            

Connected the SCL and SDA lines with 10k pull-up resistors.

Configured I2C in master-transmitter mode.

Verified pin muxing for the I2C lines.

The MCP79410 address is 0x6F as per the datasheet.

I have attached:

1. The source code I am using.

//#############################################################################
//
// FILE:   empty_driverlib_main.c
//
//! \addtogroup driver_example_list
//! <h1>Empty Project Example</h1> 
//!
//! This example is an empty project setup for Driverlib development.
//!
//
//#############################################################################
//
//
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//   notice, this list of conditions and the following disclaimer.
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//   Redistributions in binary form must reproduce the above copyright
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//   its contributors may be used to endorse or promote products derived
//   from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// $
//#############################################################################

//
// Included Files
//
#include "driverlib.h"
#include "device.h"
#include "board.h"
#include "c2000ware_libraries.h"

#define MCP79410_ADDRESS 0x6F

uint8_t hours, minutes, seconds;

void RTC_setTime(uint8_t hours, uint8_t minutes, uint8_t seconds);
void RTC_getTime(uint8_t *hours, uint8_t *minutes, uint8_t *seconds);

// // ===== Function Prototypes =====
 void initI2C(void);
// void mcp79410_writeByte(uint8_t regAddr, uint8_t data);
// uint8_t mcp79410_readByte(uint8_t regAddr);
 void mcp79410_setTime(void);
 void mcp79410_readTime(void);
// uint8_t bcdToDec(uint8_t val);


// uint8_t data;
// uint8_t raw_seconds;
// uint8_t raw_minutes;
// uint8_t raw_hours;
// uint8_t seconds;
// uint8_t minutes;
// uint8_t hours;

//     uint8_t i;
//     uint8_t timeData[3];

//
// Main
//

void main(void)
{

    //
    // Initialize device clock and peripherals
    //
    Device_init();

    //
    // Disable pin locks and enable internal pull-ups.
    //
    Device_initGPIO();

    //
    // Initialize PIE and clear PIE registers. Disables CPU interrupts.
    //
    Interrupt_initModule();

    //
    // Initialize the PIE vector table with pointers to the shell Interrupt
    // Service Routines (ISR).
    //
    Interrupt_initVectorTable();

    //
    // PinMux and Peripheral Initialization
    //
    Board_init();

    //
    // C2000Ware Library initialization
    //
    C2000Ware_libraries_init();

    //
    // Enable Global Interrupt (INTM) and real time interrupt (DBGM)
    //
    // EINT;
    // ERTM;
 
    initI2C();

    I2C_setSlaveAddress(I2CA_BASE, MCP79410_ADDRESS);  // Set RTC address

    RTC_setTime(12, 30, 45);  // Set time to 12:30:45

    while (1) {
        RTC_getTime(&hours, &minutes, &seconds);
        DEVICE_DELAY_US(1000000);  // Delay 1 second
    }

}

//
// End of File
//

void initI2C(void)
{
    // I2C SDA and SCL pin setup
    GPIO_setPinConfig(GPIO_32_I2CA_SDA);
    GPIO_setPadConfig(33, GPIO_PIN_TYPE_PULLUP);
    GPIO_setQualificationMode(33, GPIO_QUAL_ASYNC);

    GPIO_setPinConfig(GPIO_33_I2CA_SCL);
    GPIO_setPadConfig(32, GPIO_PIN_TYPE_PULLUP);
    GPIO_setQualificationMode(32, GPIO_QUAL_ASYNC);

    // I2C Master config
    I2C_disableModule(I2CA_BASE);
    I2C_initMaster(I2CA_BASE, DEVICE_SYSCLK_FREQ, 100000, I2C_DUTYCYCLE_33);
    I2C_setAddressMode(I2CA_BASE, I2C_ADDR_MODE_7BITS);
    I2C_setBitCount(I2CA_BASE, I2C_BITCOUNT_8);
    I2C_setSlaveAddress(I2CA_BASE, MCP79410_ADDRESS);
    I2C_setEmulationMode(I2CA_BASE, I2C_EMULATION_FREE_RUN);
    I2C_enableModule(I2CA_BASE);
}



// void I2C_init(void) {
//     // Initialize I2C as master
//     I2C_initMaster(I2CA_BASE, DEVICE_SYSCLK_FREQ, 100000, I2C_DUTYCYCLE_33);
//     I2C_setSlaveAddress(I2CA_BASE, RTC_I2C_ADDR);
//     I2C_enableModule(I2CA_BASE);
// }

void RTC_setTime(uint8_t hours, uint8_t minutes, uint8_t seconds) {
    I2C_setConfig(I2CA_BASE, I2C_MASTER_SEND_MODE);
    I2C_sendStartCondition(I2CA_BASE);
    I2C_putData(I2CA_BASE, 0x00);  // Address of seconds register
    I2C_putData(I2CA_BASE, seconds);
    I2C_putData(I2CA_BASE, minutes);
    I2C_putData(I2CA_BASE, hours);
    I2C_sendStopCondition(I2CA_BASE);
}

uint8_t bcdToDec(uint8_t val)
{
    return ((val >> 4) * 10 + (val & 0x0F));
}

void RTC_getTime(uint8_t *hours, uint8_t *minutes, uint8_t *seconds)
{
    // Step 1: Set register pointer to 0x00 (seconds register)
    I2C_setConfig(I2CA_BASE, I2C_MASTER_SEND_MODE);
    I2C_sendStartCondition(I2CA_BASE);
    I2C_putData(I2CA_BASE, 0x00);  // Point to seconds register
    while(I2C_isBusBusy(I2CA_BASE));
    
    // Step 2: Repeated start for reading
    I2C_setConfig(I2CA_BASE, I2C_MASTER_RECEIVE_MODE);
    I2C_sendStartCondition(I2CA_BASE);

    uint8_t rawSeconds = I2C_getData(I2CA_BASE);
    uint8_t rawMinutes = I2C_getData(I2CA_BASE);
    uint8_t rawHours   = I2C_getData(I2CA_BASE);

    I2C_sendStopCondition(I2CA_BASE);

    // Step 3: Convert from BCD to decimal
    *seconds = bcdToDec(rawSeconds & 0x7F);  // Mask ST bit
    *minutes = bcdToDec(rawMinutes);
    *hours   = bcdToDec(rawHours & 0x3F);    // Mask 24-hour mode bits
}

2. Oscilloscope waveforms of the SCL and SDA lines during I2C communication attempts.

I would appreciate it if you could help me identify what might be going wrong or what I'm missing.

Thank you in advance.