Application Note
10 of 38
001-86233 Rev. *I
2021-11-04
PSoC™ 4 MCU low
-power modes and power reduction techniques
Low-power mode details
wake the device from stop mode.
Currently,
ModusToolbox™ software
does not support any
PSoC™
4 MCU
device that supports stop mode.
Note:
The
PSoC™
4000, 4000S, 4100S, 4100S plus, 4100S plus 256k, 4100S max, 4200DS, 4500S, 4700S,
4100PS and analog coprocessor product lines do not support stop mode.
3.4.1
Stop mode wakeup sources
The dedicated wakeup pin P0[7] is the only wakeup source available in stop mode. You can set its input wakeup
polarity to rising or falling edge by calling the
CySysPmSetWakeupPolarity()
function.
3.4.2
Stop mode transitions
To enter stop mode, call
CySysPmStop()
. This function configures the device for Stop mode, including
freezing the I/O states. If you use the dedicated wakeup pin, set its input wakeup polarity before entering stop
mode with the
CySysPmSetWakeupPolarity()
function.
Exit from stop mode occurs when the dedicated pin wakeup is triggered, the reset signal goes LOW, or if power
is cycled. Upon exiting stop mode,
PSoC™
4 MCU resets. Upon return to active mode after reset, you can call
CySysPmGetResetReason()
to determine whether stop mode was exited by toggling the wakeup pin or a
power cycle. After a wakeup pin reset, the GPIO states remain frozen and must be unfrozen using the
CySysPmUnfreezeIo()
function before the pin states can be changed. There is no need to call
CySysPmfreezeIo()
before entering stop mode because
CySysPmStop()
freezes I/O cells implicitly.
3.4.3
Stop mode use cases
Use stop mode when the absolute minimum power consumption and functionality are required. It is most
useful in applications where a host controller or a user input such as a button press can trigger the dedicated
wakeup pin, and the power supply topology does not allow disconnecting power from the device.
For more information on the power mode transition APIs, see the
