MSP432P401R: VL6180X Proximity Sensor I2C Problem

Hi Bruce,

Thanks for looking into the library. Yes, I am writing all of those registers. Though they don't offer explanations in the Arduino library, STMicroelectronics (the manufacturer of the VL6180X) has documentation available on their website such as datasheets and C libraries that explain that those are private registers that need to be written for proper initialization of the sensor.

I have tried reading back some of those libraries after I have written them and I keep getting 0 as output. I guess this means that I'm not writing the registers correctly.

However, I'm not sure what is going wrong. When I read from a register, I have to write to the sensor first with the correct register address. I'm pretty sure I'm doing the read operation correctly because I can correctly get the device ID from the 0x0000 register. Additionally, when I do my write operation, I use

int configRegWriteInitVL(uint16_t reg, uint8_t data) {
    MAP_I2C_setSlaveAddress(EUSCI_B1_BASE, VL_6180X_ADDR);
    printf("writing\n");
    MAP_I2C_setMode(EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_MODE);

    uint8_t regLSB = reg & 0xFF;
    uint8_t regMSB = reg >> 8;
    int result = false;
    MAP_I2C_masterSendMultiByteStart(EUSCI_B1_BASE, regMSB);
    MAP_I2C_masterSendMultiByteNext(EUSCI_B1_BASE, regLSB);
    result = MAP_I2C_masterSendMultiByteFinishWithTimeout(EUSCI_B1_BASE, data, TEMP_TIMEOUT);
    printf("write result: %d\n", result);
    return result;
}

and when I am writing the registers, it prints out "write result: 1" for all of the write operations, which indicates that the writes were completed successfully. Do you have any insights on what could be going wrong?

I should also note that this is what my read operation looks like: 

uint8_t configReadRegVL(uint16_t reg) {
    int result = false;
    uint8_t range = 0;
    uint8_t regLSB = reg & 0xFF;
    uint8_t regMSB = reg >> 8;

    MAP_I2C_setSlaveAddress(EUSCI_B1_BASE, VL_6180X_ADDR);
    MAP_I2C_setMode(EUSCI_B1_BASE, EUSCI_B_I2C_TRANSMIT_MODE);

    MAP_I2C_masterSendMultiByteStart(EUSCI_B1_BASE, regMSB);
    result = MAP_I2C_masterSendMultiByteFinishWithTimeout(EUSCI_B1_BASE, regLSB, TEMP_TIMEOUT);

    if (result == true) {
        printf("vl read success\n");
        MAP_I2C_setMode(EUSCI_B1_BASE, EUSCI_B_I2C_RECEIVE_MODE);

        range = MAP_I2C_masterReceiveSingleByte(EUSCI_B1_BASE);
        printf("regvalue: %d\n", range);
    }

    return range;
}

Additionally, the "unexplained write operations" you mentioned that appeared in the Adafruit library are initializers that written when the device is reset. Thus, theoretically, if I use the sensor with the Arduino first and then don't use the initializers when I use the sensor with the MSP, the sensor should already be initialized correctly. However, I did that and it still gives me the VCSEL error. I don't know if this information helps or makes the problem even more complicated.

Hi Bruce,

Thanks for looking through the Adafruit documentation. The register RESULT_RANGE_STATUS (0x4D) is checked in the readRange() method in the Adafruit library. I have attempted to ignore the error code before I posted on the forum, and the sensor returns a value of 0 for every measurement.

Hi Bruce,

Sorry for the delayed response. I did not go into school over the weekend and I forgot to take the sensor home with me. I tried wiggling the GPIO0 (SHDN) pin to reset it before the program started and the same error occurred.

I also read the register before doing any setup and interestingly enough, it returned 0x01 which means no error. However, immediately after that, I read the device ID register and it returned the wrong value. Then, when I read the problematic register again, it returned the VCSEL Continuity error. I tried doing the above steps with wiggling the SHDN pin and not wiggling the SHDN pin, and the same thing occurred both times.

I also tried using the 5V output on the Launchpad and I still got the same error.

I really appreciate the effort you're putting into helping me but right now, it's looking like this is an error that can't be fixed. Sorry for wasting your time.