WEBENCH® Tools/HDC1010: Don't know

Hi Josh,

Thanks for coming back.

Would like to ask you.  If I put a pull-up resistor of 1.5k to the DRDYn pin and my code is as below, is there anything wrong that stops the DRDYn pin to be pulled low?  It always gets stuck at while(HDC1010_DRDYN_PIN.read());, which doesn't go low.

The slvAddr is 0x42, 

The regAddr is 0x00,

The cnt is 0x04

static bool hdc1010ReadFromRegister (uint8_t slvAddr, uint8_t regAddr, uint8_t cnt, uint8_t *rdBuffer)
{
int ret;
char data_write[3];
char data_read[6];
uint8_t slv_addr_8bit = (slvAddr << 1);
uint8_t i;

data_write[0] = (char)regAddr;

i2c.lock();
ret = i2c.write((int)slv_addr_8bit, data_write, 1, 1);
while(HDC1010_DRDYN_PIN.read());

if (ret == 0) {
    ret = i2c.read((int)slv_addr_8bit, data_read, (int)cnt, 0);
    if (ret != 0) {
        i2c.unlock();
        return false;
    }
} else {
    i2c.unlock();
    return false;
}
i2c.unlock();

    for (i = 0; i < cnt; i++) {
        rdBuffer[i] = (uint8_t)data_read[i];
    }
return true;
}

Regards,

Nelson

Hi Josh,

Using the above code, when I purposely touch the HDC1010_DRDYN_PIN pin to a ground pin, I can get the sensor's temperature and humidity readings.

It shows that the code is working.  But when HDC1010_DRDYN_PIN pin is connected to the DRDYn pin of the sensor, it just doesn't go low.  

Do you know why it is so?  What have I missed that causes the pin doesn't go low?

Hope to hear from you soon.

Regards,

Nelson

Nelson - 

Please attach your schematic here. 

Hi Josh,

The circuit is as below...

Regards,

Nelson

Address lines? Bypass Cap? 

Any logic captures of what your code behavior which you can compare to what i captured?  

Hi Josh,

I attach the waveform here..

I am using slave address 0x42.

As can be seen, after sending address 0x00, the DRDYn pin (the blue waveform) is still high. 

regards,

Nelson

Nelson - 

Can you check that you are respecting the tLOW time after start condition? (should be 1.3uSec or greater) - this would be measured from SCL at GND to base of first rise of next clock cycle - looks like you are at 20uSec per division, i looked at clock frequency based on that, looks like you are running 100kHz, so that is what led me to ask this question as it looks like it might be too short, what you have there. Also, this would shift everything over like its supposed to be - if you increase that time, as the ACKs here are questionable. They are not strong and they don't line up well with clock and i see an extra blip there in the middle, right after the ninth clock. 

Did you also send the SOFT_RESET before this? 

Can you try weaker pull up resistors? 

Do you have the bypass capacitor installed? 

Hi Josh,

Does it matter with 100kHz I2C?  If it does matter, when I purposely touch the DRDYn pin to a ground pin, it won't be able to read the register 0x00 to 0x01 anymore.  But when I touch the DRDYn pin to a ground pin, it can still read the registers.  That means the 100khz I2C has no problem in reading.

The problem now is that why the DRDYn pin doesn't go low?  Is that any possibility that you can think of?

Regards,

Nelson