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62 lines
2.0 KiB
62 lines
2.0 KiB
9 years ago
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Power control
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The ESP8266 provides the ability to change the CPU frequency on the fly, and
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enter a deep-sleep state. Both can be used to manage power consumption.
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Changing the CPU frequency
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--------------------------
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The machine module has a function to get and set the CPU frequency. To get the
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current frequency use::
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>>> import machine
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>>> machine.freq()
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80000000
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By default the CPU runs at 80MHz. It can be change to 160MHz if you need more
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processing power, at the expense of current consumption::
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>>> machine.freq(160000000)
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>>> machine.freq()
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160000000
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You can change to the higher frequency just while your code does the heavy
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processing and then change back when its finished.
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Deep-sleep mode
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---------------
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The deep-sleep mode will shut down the ESP8266 and all its peripherals,
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including the WiFi (but not including the real-time-clock, which is used to wake
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the chip). This drastically reduces current consumption and is a good way to
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make devices that can run for a while on a battery.
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To be able to use the deep-sleep feature you must connect GPIO16 to the reset
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pin (RST on the Adafruit Feather HUZZAH board). Then the following code can be
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used to sleep and wake the device::
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import machine
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# configure RTC.ALARM0 to be able to wake the device
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rtc = machine.RTC()
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rtc.irq(trigger=rtc.ALARM0, wake=machine.DEEPSLEEP)
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# set RTC.ALARM0 to fire after 10 seconds (waking the device)
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rtc.alarm(rtc.ALARM0, 10000)
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# put the device to sleep
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machine.deepsleep()
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Note that when the chip wakes from a deep-sleep it is completely reset,
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including all of the memory. The boot scripts will run as usual and you can
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put code in them to check the reset cause to perhaps do something different if
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the device just woke from a deep-sleep. For example, to print the reset cause
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you can use::
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if machine.reset_cause() == machine.DEEPSLEEP_RESET:
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print('woke from a deep sleep')
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else:
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print('power on or hard reset')
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