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Doc#40AN7002.00
© Silicon Microstructures, Inc. 2001 – 2017. All rights reserved +1(408) 577-0100 | sales@si-micro.com |
www.si-micro.com
Sleep mode application note for SMI
products with I2C protocol B
1. Description
The application note is used to set I
2
C protocol B type devices into sleep mode for power saving
purpose. The specific CMD register value can be written for suspending the device into sleep
mode and the device enabling sequence is also discussed here to wake the device up for normal
operation.
2. CMD register value for sleep mode
Command register(CMD): 0x22
0x22
CMD
bits
name
default
rw
Description
15:0
cmd
0
w
Writing to this register controls the state of the SMI devices.
0x6C32: SLEEP Mode
Initiate the power state SLEEP, powering down the ASIC
Register Read or Write are performed via the digital communication interface.
After power-up of the IC all registers except STATUS and CMD are write-
protected.
Power state sleep: The entire chip is powered down. All pins of the device are
high impedance. Only wake up event monitoring is active.
Current consumption in sleep mode is less than 10μA*
(Typical values based on limited quantity of samples)
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Doc#40AN7002.00
© Silicon Microstructures, Inc. 2001 – 2017. All rights reserved +1(408) 577-0100 | sales@si-micro.com |
www.si-micro.com
3. Sleep mode command and wake up method
How to go to sleep mode?
o Write 0x6C32 into CMD register
o Example code based on Arduino platform
Wire.write(0x22); //Send CMD-register address
Wire.write(0x32); //Send sleep command low byte (low byte first)
Wire.write(0x6C); //Send sleep command high byte
How to wake it up?
o The following wake up conditions are supported:
Rising edge on pin SCK/SCL
Rising edge on pin SCK/SCL with NCS asserted