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esp-idf/examples/system/ulp_adc
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Ivan Grokhotkov 3c583a7655 sdkconfig: set CONFIG_ESP32_DEEP_SLEEP_WAKEUP_DELAY=2000 by default 
To increase the chances that the examples work out of the box, this
change is raising the default deep sleep wakeup delay to 1ms.
If GPIO15 is low at startup, ROM code takes less time to execute
(because no logging is performed), so more time may be needed to allow
flash chip to become ready.
2017-05-25 10:51:39 +08:00
..
main examples: add ULP ADC example 2017-05-16 13:15:02 +08:00
Makefile examples: add ULP ADC example 2017-05-16 13:15:02 +08:00
README.md examples: add ULP ADC example 2017-05-16 13:15:02 +08:00
sdkconfig.defaults sdkconfig: set CONFIG_ESP32_DEEP_SLEEP_WAKEUP_DELAY=2000 by default 2017-05-25 10:51:39 +08:00

README.md

ULP ADC Example

This example demonstrates how to use the ULP coprocessor to poll ADC in deep sleep.

ULP program periodically measures the input voltage on GPIO34. The voltage is compared to two thresholds. If the voltage is less than the low threshold, or higher than the high threshold, ULP wakes up the system.

By default, thresholds are set to 1.35V and 1.75V, approximately.

Average current drawn by the ESP32 in this example with the default configuration (10Hz measurement period, 4x averaging) is 80 uA.

Example output

Below is the output from this example. GPIO15 is pulled down to ground to supress output from ROM bootloader.

Not ULP wakeup
Entering deep sleep

Deep sleep wakeup
ULP did 1531 measurements
Thresholds:  low=1500  high=2000
Value=973 was below threshold
Entering deep sleep

Deep sleep wakeup
ULP did 2 measurements
Thresholds:  low=1500  high=2000
Value=0 was below threshold
Entering deep sleep

Deep sleep wakeup
ULP did 2 measurements
Thresholds:  low=1500  high=2000
Value=0 was below threshold
Entering deep sleep