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HDC1080: HDC1080 Temp Read Back Issue

Qiang Ren
Intellectual 1575 points
Part Number: HDC1080

Hello Team,

Currently my customer is using HDC1080 to read back board temperature and humidity. We find there is read back issue, could you please help with the below question? Thanks!

First we checked that the I2C driver code is working normally, by reading back the device ID correctly.

But when we try to read back the temperature, the device can't trigger ACK. The sequence is as below(I2C address is 0x40):

1. Set 0x02 reg B[12] as "1".

2. Trigger measurement, with address pointer set to 0x00. Based on the D/S, we need to send the STOP symbol after trigger measurement. Is there any timing sequence between the STOP symbol and the CLK edge requirements?

3. Read outputs. Read registers 0x00 and 0x01 without any extra write command. We find that when we try to access to 0x00 reg, there is no ACK sent from HDC1080. 

Best Regards,

Qiang

  • 0
    TI__Mastermind 41195 points

    Hi Qiang,

    You must not begin your read transaction with a write transaction. You must perform only read transaction to fetch the data. 

    In your second picture, you have Figured 12 followed by Figure 13. "Data Not Ready" NACK is the expected behavior.

    If you allow the appropriate wait after Figure 12, you will get Figure 14.

    The appropriate wait time is dependent on configuration, but could be 12.85ms typical.

    thanks,

    ren