ChipCap® 2 Humidity and Temperature Sensor
22
Application Guide
5.3.2
Data Fetch in Sleep Mode (cont.)
Figure 14 below shows the measurement and communication sequence for Sleep Mode. The master sends an MR
command to wake the ChipCap 2 from power down. After ChipCap 2 wakes up, a measurement cycle is performed
consisting of both a temperature and a capacitance conversion followed by the ChipCap 2 Core correction calculations.
At the end of a measurement cycle, the digital output register and alarms will be updated before powering down. An
I
2
C data fetch (DF) is performed during the power-down period to fetch the data from the output register. In I
2
C the
user can send another MR to start a new measurement cycle without fetching the previous data. After the data has been
fetched, the ChipCap 2 remains powered down until the master sends an MR command.
Figure 14: Measurement Sequence in Sleep Mode
Figure 15:
I
2
C Data Fetching in Sleep Mode
ChipCap 2
Activity
I
2
C
Activity
Command wakes
ChipCap 2
Power
Down
Power
Down
Temp
Conv & Calc
Cap
Conv & Calc
Write new corrected
signal measurement to
output register (I
2
C)
Valid read
occurs
ChipCap 2
Activity
Power
Down
Temp
Conv & Calc
Cap
Conv & Calc
Power
Down
Write new corrected
signal measurement to
output register (I
2
C)
Command wakes
ChipCap 2
I
2
C
Activity
Valid read
occurs
Stale values
