Pycom FiPy, Руководство пользователя, Страница: 168 / 496

ADC
This example is a simple ADC sample. For more information please see
ADC
.
from machine import ADC
adc = ADC( 0 )
adc_c = adc.channel(pin= 'P13' )
adc_c()
adc_c.value()
Calibration
Currently the ESP32's ADC is not calibrated from the factory. This means it must be
calibrated each time you wish to use it. To do this you must firstly measure the internal
voltage reference. The following code will connect the 1.1v reference to
P22
from machine import ADC
adc = ADC()
# Output Vref of P22
adc.vref_to_pin( 'P22' )
Now that the voltage reference is externally accessible you should measure it with the most
accurate voltmeter you have access to. Note down the reading in millivolts, e.g.
1120
. To
disconnect the 1.1v reference from
P22
please reset your module. You can now calibrate
the ADC by telling it the true value of the internal reference. You should then check your
calibration by connecting the ADC to a known voltage source.
# Set calibration - see note above
adc.vref( 1100 )
# Check calibration by reading a known voltage
adc_c = adc.channel(pin= 'P16' , attn=ADC.ATTN_11DB)
print(adc_c.voltage())
4.2.7 ADC
168