CCS/MSP432P401R: I2C communication gets stuck at Poll for transmit interrupt flag

>        __delay_cycles(1000);// Delay for sensor to be ready

Supposing that your CPU is running at 3MHz, this is about 300 usec. VL53L0x data sheet (DocID029104 Rev 2) Fig 9 says that startup can take (40+1) msec. My guess is that you're getting a NACK since the device hasn't completed startup.

SendSingleByte doesn't check for NACK. One option is to use I2C_masterSendSingleByteWithTimeout. If that function times out, it does not send a Stop, so if you see a failure (returns false) you need to call something like I2C_masterReceiveMultiByteStop (don't dwell on the function's name). I'm guessing that the units for the "timeout" parameter are about 1 usec (at 3MHz).

And bump your startup delay to something like 45 msec.

thanks for you answer.

i tried it with setting a higher delay and the MAP_I2C_masterSendSingleByteWithTimeout function, with no success. It is always false.

__delay_cycles(135000);// 45ms at 3Mhz Delay for sensor to be ready
//__delay_cycles(2160000);// 45ms at 48 Mhz
bool test = MAP_I2C_masterSendSingleByteWithTimeout(EUSCI_B1_BASE,address,1000);
        if(test)
        {
            regC0 = MAP_I2C_masterReceiveSingleByte(EUSCI_B1_BASE);
        }
        else
        {
            printf("False");
        }

Maybe you have another idea?

Are you seeing a NACK? Pause in the debugger, and check Registers->EUSCI_B1->IFG for UCNACKIFG.

[Edit: Also, as a matter of completeness, add a:

> MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P6,GPIO_PIN0);

to make sure the device really resets (XSHUT low then high).]

thanks again for you answer.

i put MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P6,GPIO_PIN0); at the beginning so that the Port is low, but it didnt change anything.

I dont get a NACK.

That is a picture of my EUSCI_B1.

I find out that it is only workin with the MAP_I2C_masterSendSingleByteWithTimeout function, MAP_I2C_masterSendSingleByte does not work.

But now i stuck at writing into a register:

void writeReg (uint8_t reg, uint8_t value)
{
    bool reg_bool = MAP_I2C_masterSendSingleByteWithTimeout(EUSCI_B1_BASE,reg,1000);
    bool value_bool = MAP_I2C_masterSendSingleByteWithTimeout(EUSCI_B1_BASE,value,1000);
    if (reg_bool && value_bool)
    {
        printf("test");
    }
}

the bool values are just for testing. Do i need to use MAP_I2C_masterSendMultiByteStart for writing into a register?

Can you tell me which unit the timout is, is it seconds or ms or cpu-cycles? The documentation doesnt declare a unit: timeout is the amount of time to wait until giving up

Sorry for my late response!

I got it working to write to the register even to a 16bit register.

But now i have a new problem... When i debug the code everything is working as expected, but if I run the code without debugging it cannot write to the registers. I think it's to fast.

I read in the vl53l0x doc about the "Bus free time between transmissions" so i added delays but i didnt work.

Here is an example:

void writeReg (uint8_t reg, uint8_t value)
{
    __delay_cycles(96000); //2 ms  48Mhz
    bool reg_bool = MAP_I2C_masterSendMultiByteStartWithTimeout(EUSCI_B1_BASE,reg,1000);
    bool value_bool = MAP_I2C_masterSendMultiByteFinishWithTimeout(EUSCI_B1_BASE,value,1000);
    MAP_I2C_masterSendMultiByteStopWithTimeout(EUSCI_B1_BASE,1000);
    __delay_cycles(96000); //2 ms  48Mhz
    if (reg_bool && value_bool)
    {
        printf("writeReg success \n");
    }
    else
    {
        printf("writeReg failed \n");
    }
    //__delay_cycles(6000); //2 ms 3Mhz
    //__delay_cycles(96000); //2 ms 48Mhz
}

Does anyone have any ideas?

thanks in advance!

It already fails when I try to read from i2c for the second time.

uint8_t readReg (uint8_t address)
{
    uint8_t value=0x00;
    /* Wait until ready */
        while (MAP_I2C_isBusBusy(EUSCI_B1_BASE)){
            ;
        }
    bool reag_reg = MAP_I2C_masterSendSingleByteWithTimeout(EUSCI_B1_BASE,address,100000);
    if(reag_reg)
    {
        value = MAP_I2C_masterReceiveSingleByte(EUSCI_B1_BASE);
        printf("read success \n");
    }
    else{
        printf("read failed \n");
    }
    //__delay_cycles(6000); //2 ms bei 3Mhz
        __delay_cycles(96000); //2 ms bei 48Mhz
    return value;
}

The bus stays busy. register view:

UCBSTATW 0x0350eUSCI_Bx Status Register [Memory Mapped]

UCBCNT 00000011 Hardware byte counter value

UCSCLLOW 1 - UCSCLLOW_1 SCL low

UCGC 0 - UCGC_0 General call address received

UCBBUSY 1 - BUSY Bus busy

I did it, I had to add a delay in some places.