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TF-Luna consumes 1.5mW during sleep and on average 260mW during awakening. The
awakening will last about 8.5ms. Based on the information, it consumes on average
3.7mW if we wake it up every second and on average 1.72mW if we wake it up every ten
seconds.
6.11.2 Ultra-low Power Mode with I2C communication
(1) Turn on Ultra-low Power Mode
In order to turn on and save Ultra-low Power Mode, users need to write three
consecutive bytes [0x01, 0x01, 0x02] to the address 0x1F.
(2) Bring up Range-finding
Users can attempt reading any one of valid or invalid register addresses (which will not
make us receive ACK from the slave device). In this way, TF-Luna will detect the change of
voltage on Pin 2 and thus it will be awaken. TF-Luna will perform range-finding once upon
each awakening, and update the result on the register. It will not fall back to sleep mode
until the user performs a read-register operation.
Figure 8 Time sequence of Ultra-low Power Mode with I2C communication
(3) Turn off Ultra-low Power Mode
Reading the register will make TF-Luna enter sleep mode once again, therefore, in order
to turn off the Ultra-low Power Mode, users need to write three consecutive bytes [0x00,
0x01, 0x02] to the address 0x1F after the awakening. It should be done no sooner than
6ms after the awakening).
(4) Estimation of Power Consumption
TF-Luna consumes 1.5mW during sleep and on average 200mW during awakening.
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