TMP006: Reading registers atomically

Hi Michael,

Please see the answers to your questions here:

1.The DRDY bit indicates "Object voltage and ambient temperature results are ready to read". Does this mean that no further updates occur until the flag is cleared by reading the registers?

ANS] The results will continue to update even after the flag is set. The flag is mainly intended to be used with one shot command. This will indicate that the one-shot is done and the results can be read. If part is in continuous conversion mode, then DRDY flag is set at end of each conversion.

2. When DRDY=1, is it safe to read both Vobj and Tamb without further checks of DRDY? Is the following scenario possible: (i) the master reads VOBJ and thereby clears DRDY, (ii) the sensor happens to complete a conversion at this very moment and writes Tamb, (iii) the master reads TAMB at the same time.

ANS] Result registers updated at the end of the conversion. How ever there is a small delay between these updates. The DRDY flag is set only after all result registers are updated. So if you read the registers after DRDY =1, then you will be fine, given that the read happens before the next conversion finishes.

3. Are 16-bit reads always safe? When reading a register without checking DRDY (or if a collision as in 2. occurs), is it possible that a 16-bit read yields inconsistent data with LSB and MSB from two different conversions?

ANS] Yes. Data is synchronized internally to make sure that device does not give 8bits of old value and next 8 bits of new value. All 16 bits will belong to same value either old or new.