a potentiometer.
The ESP32-S3 chip integrates two ADC analog-to-digital converters, the measurement range is 0mV-3100mV, and the resolution is 12bit, that is, 0mV-3100mV is divided into 2^12=4096 levels, and each level is a digital quantity .
The two ADC analog-to-digital converters each have 10 measurement channels, ADC1 is GPIO1 ~ 10, and ADC2 is GPIO11 ~ 20.
GND is connected to GND, VCC is connected to 3V3, the S output terminal is connected to GPIO11 pin, and channel 1 of ADC2 is used for measurement.
GPIO1~20 pins can be used as ADC input pins.
from machine import Pin,ADC
import time
adc11 = ADC(Pin(11),atten=ADC.ATTN_11DB)
#adc11 = ADC(Pin(11))
#adc11.atten(ADC.ATTN_11DB)
while True:
read=adc11.read()
read_u16 = adc11.read_u16()
read_uv = adc11.read_uv()
print("read={0},read_u16={1},read_uv={2}".format(read,read_u16,read_uv))
time. sleep_ms(100)| Attenuation value | Measurable input voltage range |
|---|---|
ADC.ATTN_0DB |
0 mV ~ 950 mV |
ADC.ATTN_2_5DB |
0 mV ~ 1250 mV |
ADC.ATTN_6DB |
0 mV ~ 1750 mV |
ADC.ATTN_11DB |
0 mV ~ 3100 mV |
ADC(*, atten) initializes the ADC channel of a GPIO pin, and you can choose to use atten to set the attenuation value, which controls the measurable input voltage range of the chip. If not set, it will be the default value atten=ADC.ATTN_0DB or the value set last time.
You can modify the attenuation value through ADC.atten() after initializing an ADC channel.
ADC.read() reads the ADC and returns the read result. The ADC of the ESP32-S3 chip returns data with 12-bit precision.
ADC.read_u16() reads the ADC and returns 16-bit data.
ADC.read_uv() returns the calibrated input voltage in uV microvolts according to the characteristics of the ADC. Return values only have mV millivolt resolution (ie, will always be in multiples of 1000 microvolts).
The WiFi function also uses ADC2, so trying to read analog values from ADC2’s measurement channels GPIO11 ~ 20 while WiFi is active will throw an exception.
It is recommended to use ADC.read_uv() to read the voltage value, which is a decimal constant returned after calibration according to the characteristics of the ADC analog-to-digital converter, which is more accurate than the other two reading methods. At the same time, it is also recommended to directly divide the operation when using: ADC.read_uv()//1000 to get the data of mV millivolt resolution.
Directly print out ADC.read() or ADC.read_u16() to get the decimal value, you can use the hex() function to convert the data type into hexadecimal, for example hex(ADC.read() ), or use the bin() function to convert the data type to binary.