LP-MSPM0G3507: I2C Data transmission and Reception

Hi Tejal,

Sure. You could set one I2C as controller and another as slave and just connect SCL and SDA pin together.

Do I also need to connect pull-up resistors for I2C communication? and could you provide a simple sample code for setting up I2C communication.

Thank you,
Tejal

Hi Tejal,

Yes, you could either use the internal pull-up resistors or external pull-up resistors.

As for example, you could merge the i2c controller and target example into one project for you application. The interrupt example could be used for i2c target.

Hi Pengfei,

I tried merging the I2C controller and target example, but I am not getting an acknowledgment from the target device. I am also attaching the output which I observed on the logic analyzer.

Thank you,
Tejal

Which examples did you merge? I expect you'd want to use an interrupt-driven model on the target side.

Did you change the target I2C address on both sides?

Yes I changed the I2C address on both side and also, I am using interrupt driven code on target side, and following 2 examples I merged:

1) i2c_controller_multibyte_fifo_poll and 2) i2c_target_multibyte_fifo_interrupt

Hi Tejal,

It is correct that you are using the interrupt example for I2C target.

There are some items you could check:

• You are writing to address 0x10 from I2C master, have you change the I2C target address as 0x10?
• Have you pull-up the SCL and SDA pin?
• For I2C target code, make sure it is completely follow the SDK example, especially for the enabling of interrupt and interrupt handler achievement.  

Best Regards,

Pengfei

Can you post your resulting (merged) code? Sometimes all it takes is a typo.

----------------

For the target side, the contents of main() should be suitable for a "target_init()" function, except for:

    DL_SYSCTL_enableSleepOnExit();

This should be removed, since it has a global effect on the program. (It could produce the symptom you're seeing.)

    while (1) {
        __WFI();
    }

This should be removed. (I'm guessing you already did this one.)

Thank you for your feedback. I have made the necessary adjustments to the code as per your suggestions. I am attaching the updated code for your review. Could you please check the resulting (merged) code? 

#include <ti/driverlib/m0p/dl_interrupt.h>
#include "ti_msp_dl_config.h"

#define I2C_TX_PACKET_SIZE (8)

#define I2C_RX_PACKET_SIZE (5)

#define I2C_TX_MAX_PACKET_SIZE (16)

#define I2C_RX_MAX_PACKET_SIZE (16)

uint8_t gTxPacket[I2C_TX_PACKET_SIZE] = {
    0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};

volatile uint8_t gRxPacket[I2C_RX_PACKET_SIZE];

uint32_t gTxLen, gTxCount;

/* Data sent to Controller in response to Read transfer */
uint8_t gTxPacket1[I2C_TX_MAX_PACKET_SIZE] = {0x00};
volatile uint8_t gRxPacket1[I2C_RX_MAX_PACKET_SIZE];

uint32_t gRxLen, gRxCount;


int main(void)
{
    SYSCFG_DL_init();

    gTxCount = 0;
    gTxLen   = I2C_TX_MAX_PACKET_SIZE;
    DL_I2C_enableInterrupt(I2C_1_INST, DL_I2C_INTERRUPT_TARGET_TXFIFO_TRIGGER);

    /* Initialize variables to receive data inside RX ISR */
    gRxCount = 0;
    gRxLen   = I2C_RX_MAX_PACKET_SIZE;


    DL_I2C_fillControllerTXFIFO(I2C_0_INST, &gTxPacket[0], I2C_TX_PACKET_SIZE);

    /* Wait for I2C to be Idle */
    while (!(
        DL_I2C_getControllerStatus(I2C_0_INST) & DL_I2C_CONTROLLER_STATUS_IDLE))
        ;

    DL_I2C_startControllerTransfer(I2C_0_INST, I2C_1_TARGET_OWN_ADDR,
        DL_I2C_CONTROLLER_DIRECTION_TX, I2C_TX_PACKET_SIZE);

    /* Poll until the Controller writes all bytes */
    while (DL_I2C_getControllerStatus(I2C_0_INST) &
           DL_I2C_CONTROLLER_STATUS_BUSY_BUS)
        ;

    /* Trap if there was an error */
    if (DL_I2C_getControllerStatus(I2C_0_INST) &
        DL_I2C_CONTROLLER_STATUS_ERROR) {
        /* LED will remain high if there is an error */
        __BKPT(0);
    }

    /* Wait for I2C to be Idle */
    while (!(
        DL_I2C_getControllerStatus(I2C_0_INST) & DL_I2C_CONTROLLER_STATUS_IDLE))
        ;

    /* Add delay between transfers */
    delay_cycles(1000);

    DL_I2C_startControllerTransfer(I2C_0_INST, I2C_1_TARGET_OWN_ADDR,
        DL_I2C_CONTROLLER_DIRECTION_RX, I2C_RX_PACKET_SIZE);

    for (uint8_t i = 0; i < I2C_RX_PACKET_SIZE; i++) {
        while (DL_I2C_isControllerRXFIFOEmpty(I2C_0_INST));
        gRxPacket[i] = DL_I2C_receiveControllerData(I2C_0_INST);
    }

    while (1) {
    }
}

void I2C_1_INST_IRQHandler(void)
{
    static bool dataRx = false;

    switch (DL_I2C_getPendingInterrupt(I2C_1_INST)) {
        case DL_I2C_IIDX_TARGET_START:
            /* Initialize RX or TX after Start condition is received */
            gTxCount = 0;
            gRxCount = 0;
            dataRx   = false;
            /* Flush TX FIFO to refill it */
            DL_I2C_flushTargetTXFIFO(I2C_1_INST);
            break;
        case DL_I2C_IIDX_TARGET_RXFIFO_TRIGGER:
            /* Store received data in buffer */
            dataRx = true;
            while (DL_I2C_isTargetRXFIFOEmpty(I2C_1_INST) != true) {
                if (gRxCount < gRxLen) {
                    gRxPacket1[gRxCount++] = DL_I2C_receiveTargetData(I2C_1_INST);
                } else {
                    /* Prevent overflow and just ignore data */
                    DL_I2C_receiveTargetData(I2C_1_INST);
                }
            }
            break;
        case DL_I2C_IIDX_TARGET_TXFIFO_TRIGGER:
            /* Fill TX FIFO if there are more bytes to send */
            if (gTxCount < gTxLen) {
                gTxCount += DL_I2C_fillTargetTXFIFO(
                        I2C_1_INST, &gTxPacket1[gTxCount], (gTxLen - gTxCount));
            } else {
                while (DL_I2C_transmitTargetDataCheck(I2C_1_INST, 0x00) != false)
                    ;
            }
            break;
        case DL_I2C_IIDX_TARGET_STOP:
            /* If data was received, echo to TX buffer */
            if (dataRx == true) {
                for (uint16_t i = 0;
                     (i < gRxCount) && (i < I2C_TX_MAX_PACKET_SIZE); i++) {
                    gTxPacket1[i] = gRxPacket1[i];
                    DL_I2C_flushTargetTXFIFO(I2C_1_INST);
                }
                dataRx = false;
            }
            break;

        default:
            break;
    }
}

>  DL_I2C_enableInterrupt(I2C_1_INST, DL_I2C_INTERRUPT_TARGET_TXFIFO_TRIGGER);

After this, I think you need additionally (I'm guessing at the IRQN name):

> NVIC_EnableIRQ(I2C_1_IRQN); // Enable Target interrupt in NVIC

----------

But this wouldn't result in a NACK. I wonder if the I2C_1 (target) setup in ti_msp_dl_config.c is missing a call to:

>  DL_I2C_setTargetOwnAddress(I2C_1_INST, I2C_1_TARGET_OWN_ADDR);

This is generated by sysconfig in the Example, but maybe it got lost in the merge?

----------

More generally, it seems that you're using the same Tx/Rx buffers for both sides. Maybe you've checked that it works OK, but it seems hazardous at first glance.