I'm seeing an interesting behavior from the ESP32 ADC when I'm trying to measure the ESP32's power supply's voltage (LiPo battery). I have my source supplying battery connected to a voltage divider (since the board is powered by 3.3v), and that divided voltage is connected to an ADC pin. I'm reading voltage into the pin and doubling it to get the actual voltage of the battery, however, I'm. The ESP32 was running a sketch with an empty loop. At 10V input voltage, the current draw was 0.099 A (or 99.9mA). At 5V, the current draw was a little higher, at 0.128 A (or 128mA). At 10V input voltage, the current draw was 99.9mA ESP32 is a single 2.4 GHz Wi-Fi-and-Bluetooth combo chip designed with the TSMC ultra-low-power 40 nm technology. It is designed to achieve the best power and RF performance, showing robustness, versatility and reliability in a wide variety of applications and power scenarios
i'm doing wireless sensor node using (esp32, DHT11, soil moisture and nrf24l01) and i want to add an battery to supply those sensors, also need to measure battery voltage. For the battery, voltage always change to cant use as a Vcc reference, so i find there is an internal reference voltage. Could anyone done with this give me some instruction. Input Voltage for esp8266/esp32. Arduino Forum > Using Arduino > General Electronics > Input How much voltage is minimum and how much is the maximum? Are 3.3V enough, when i only want to wire an sd card adapter on my esp32 which needs 3.3V? Wawa. Brattain Member; Posts: 15,473; Karma: 1367 ; Re: Input Voltage for esp8266/esp32 #1 Apr 05, 2017, 12:03 am. There are many ESP boards. Bare, and. Measuring True-RMS AC Voltage: Today, we will use the STM32 Maple Mini to do an AC reading. In our example, we'll get the RMS value of the power grid. This is very useful for those who want to monitor the electrical network for the Internet of Things. We will then create an appl
The issue here is that the ESP32 ADC inputs only go up to 3.3V and would give an incorrect maxed out reading for anything over about 6.4A: ((3.3 - 2.5V) / 0.125 V/A) = 6.4 I use doit esp32-wroom (doit esp32 devkitv1) as temperature sensor in my tortoise enclosure. I use this microcontroller with an 3.7v 18650 battery (4200 mAh). And it works. I connected the battery to the VIN pin. Now I would like to measure the battery power level and send a MQTT message to log this. Because I would like to know when the. fiddling around to find the ultimate way to measure the voltage of the 18650 battery powering my esp32. The project is mainly a standalone sensor project, reporting via wifi and mqtt to my broker. The key facts: wake up, connect to wifi, connect to mqtt. measure temp, humidity from a dht22. determine wifi signal strength and voltage level of battery. publish to broker, go to deep sleep for x. ESP32 Low Noise Voltage Measurements Solving the noise and linearity issues with the ESP32. The ESP32 has many great features. One of them is multiple ADC inputs. The problem is that these inputs are not very good. They suffer from noise and non linearity. The software I will present overcomes these problems in what I think is a unique way. The first thing to deal with is the noise. Once we.
However, a more fundamental problem is the voltage from the transformer is is AC and the ESP32 can't measure below 0V. You should consider converting it to DC first or else raising the zero crossing voltage to 3.3/2 = 1.65V so the peaks fall between 0V and 3.3V and doing an AC analysis from multiple ADC measurements. Brian Using the ESP32 to measure a wide range of DC voltages. Link to calculator: http://www.ohmslawcalculator.com/voltage-divider-calculator Code examples: https:..
With the speed of the ESP32 i can see the sine wav form on the voltage and current (for voltage I'm using a transformer, for current I'm using a CT). This allows me to measure the current on. Since ESP32 DAC's is 3.3v I'm using a voltage divider ( 2x10K resistors ), to split bat's voltage into ESP's GPIO36. So far nothing new or not well documented on the web. Using the voltage divider, splits the 4.0v into 1.97v (measured using a volt-meter). Battery's negative pole is connected to ESP's Gnd to get a common ground
One way to do that is reading the output voltage of the battery using an analog pin of the ESP32. However, the battery we're using here outputs a maximum of 4.2V when fully charged, but the ESP32 GPIOs work at 3.3V. So, we need to add a voltage divider so that we're able to read the voltage from the battery Measuring High Voltage DC Using ESP32. Ask Question Asked 1 year, 9 months ago. Active 1 year, 9 months ago. Viewed 347 times 1 \$\begingroup\$ I want to read high voltages, around 150VDC, using a ESP32. I plan to put this as an input into the ESP32 ADC pin. But of course, i shouldn't have voltage that high on the input of a ESP32. In ESP32 datasheet tells that ADC max input is 3.3 V with 12. Used to measure analog voltage in the range of 0-3.3V. 12-bit 18 Channel ADC. DAC pins. DAC1 and DAC2. Used for Digital to analog Conversion. Input/Output Pins. GPIO0 to GPIO39 . Totally 39 GPIO pins, can be used as input or output pins. 0V (low) and 3.3V (high). But pins 34 to 39 can be used as input only. Capacitive Touch pins. T0 to T9. These 10 pins can be used a touch pins normally used.
Circuit can be modified to measure 24 volt batteries and even more 48 volts parallel battery cluster. Voltage divider working and calculations. Nodemcu is a tiny device, it works on 3.3 volts. Since it is working on 3.3 volts its pins can source and sunk 3.3 volts only. Voltage greater than 5 volt may blow the pin or fry the nodemcu. In our case we want to measure 12 volt battery and nodemcu. You can combine this project with this one: Easy measure of AC Voltage using Arduino and ZMPT101B. Tests will be done on an incandescent light bulb, controlled by a light dimmer in series with a reference multimeter and the ACS712 current sensor module. Here's the plan: First we need to interface our module with the Arduino board and check the signal shape when the dimmer is ON - Full.
The reference voltage of ESP32 ADC is 1100mV Battery+ -> 10kOhm resistor -> measure here -> 10kOhm resistor -> Ground... will halve your battery voltage at the measuring point. Seems like the ESP32 uses an internal 1.1V voltage reference for measurements, and you can set the attenuation of the ADC for different ranges, so you don't have to worry that you're using a variable input voltage I went for the YHDC SCT-013-030 which can measure up to 30 amps of current (almost 7000 watts). More than sufficient for my small apartment. This model will output a voltage between 0 and 1, which is easy to measure using the built-in ADC of the ESP32
Unfortunately, the ESP can only measure 0-1 V - in other words, you'll need additional circuitry. But you need even more - power supplies, a case - you get the idea. Let's have a look at the HLW8012 chip. It measures voltage, current and even power - though it delivers its results in an unusual way. It pulses it's output and the frequency increases as the values increase. But. This is the Voltage sensor Module that we will be using today, This Module is capable of measuring the voltages ranging from 0.02445v to 25volts dc. But if you want to measure voltages higher than 25volts then you can watch my tutorial on how to modify this voltage sensor for monitoring higher voltages, in this tutorial I performed all the calculations. As you can see on one side we have a. #define VOLTAGE_OUT(Vin) ((Vin * R3) / (R2 + R3)) As a very rough estimation, we can take the battery voltage of 4.2V as 100% and the voltage of 3.3V as 0%. I will convert them to millivolts to avoid floating-point calculations. #define VOLTAGE_MAX 4200 #define VOLTAGE_MIN 3300 The reference voltage of ESP32 ADC is 1100mV. Let's define it This tutorial shows how to use the DHT11 and DHT22 temperature and humidity sensors with the ESP32 using Arduino IDE. We'll go through a quick introduction to these sensors, pinout, wiring diagram, and finally the Arduino sketch. Learn how to display temperature and humidity readings on a web server using the ESP32 or ESP8266 boards ESP32 Digital Voltmeter | Elektor Magazin
- Fri Feb 19, 2016 1:18 pm #41444 Okay, there are 2 problems with doing this on a Node MCU. First, while the ESP8266 should be able to measure voltage on the VDD pin of the chip, it is limited to 1.8 to 3.6 V, and if you are using that method, you are measuring the voltage after is has gone through the voltage regulator, not from Vin pin. Second, on the ADC (A0) pin the schematic shows a. The ESP8266 then reads the measured voltage drop over the 100 0.1 Ohm burden and calculates the current from that. While this setup works well for bigger current (50-250mA) the resolution of 0.1mA gets a bit noise when the ESPaper module is sleeping. It turned out that the time the module is awake consumes so much more energy than when it is asleep we can live with that issue. The NodeMCU then. . In the ESP32 analogWrite will not work, is different than the Arduino Uno. ESP32 uses 8, 10, 12, 15-bit resolution for PWM generation PWM value. Arduino Uses 8-Bit Resolution i.e.PWM range is 0-254
Peak voltage: A measurement of the largest voltage present between 0 V and the highest point on the AC cycle. It's the maximum voltage that the AC voltage attains. Peak-to-peak voltage: The difference between the highest and lowest peaks of the AC voltage. In most AC voltages, the peak-to-peak voltage is double the peak voltage. RMS voltage: The average voltage of the circuit; also called. The ESP32 does not always need to operate in beast mode! You do not usually need 240MHz x 2 worth of grunt to blink an LED. You need to realize that in MOST applications, the ESP32 is going to be doing nothing at all except waiting for something to happen. That's what real-time systems do! If your application is somewhat like this - scale the core frequency down to 80 MHz. That usually. In this ESP32 tutorial we will check how to develop a HTTP web server that will expose an API for clients to retrieve measurements of temperature, humidity and CO2, using a CO2 sensor and a DHT22 temperature and humidity sensor. The tests were performed using a DFRobot's ESP32 module integrated in a ESP32 development board.. Although it is said that the AD converter built into ESP32 is said to have poor linearity, it can be measured with practical accuracy by simply correcting it.By using M5Stack, it can be made into a compact module with a screen display, and it is used quite conveniently, for example, to check the voltage easily on the go We are going to add a simple potentiometer to the ESP32 and measure the voltage from it. Note that the on-chip ADC is not the best, as it seems to exhibit some non-linear behavior. If you need a more accurate ADC, we recommend something like this SPI ADC chip. Hardware Connections. Connect a potentiometer to the ESP32 as per the following diagram: Code: Do the Twist. In a new file, enter the.
This sytem is useful when wanting to measure current from DC circuit elements. Our simple design only consists of three parts. First, a current transducer that was used to measure current running through differnet elements. Next a Sparkfun Breadboard Power Supply Stick was used to power the sensor. Lastly, a ESP 32 Thing. This was programmed through Arduino to transform the current data onto a. IThe best battery power supply for the ESP32 is the LiFePO4 battery or the LiPo battery pack. LiFePO4 battery if your main goal is to reach a maximum battery lifetime because you do not need any extra voltage regulator between the ESP32 and the battery. Also LiFePO4 batteries are rechargeable and have a capacity up to 6,000mAh, similar to LiPo and Li-ion batteries that gives your project a. Interfacing the DHT11 sensor with ESP32 is very simple as it has only three pins. Connect the VCC and GND pin of the sensor to the 3.3 V and GND pin of ESP32. Then connect the Data pin of the sensor to the D2 pin of ESP32. After making the connections my hardware looks like this: IFTTT Setup for Temperature and Humidity Measurement
AnalogRead does indeed work on the ESP32. Many sites and posts that claim that the Analog to Digital converter of the ESP32 doesn't work. I have tested analogRead using the code below and it works as expected. The code below compiles and downloads to my ESP32 Development board and produces correct results. The input pin is [ Description. The Expandable 6 Channel ESP32 Energy Meter can measure the amount of current being used by 6 circuits at a time! Much like our Split Single Phase Energy Meter, the 6 channel energy meter uses current transformers to measure current being used by any circuit, and an AC transformer to measure voltage.An ESP32 dev board plugs directly into the energy meter to process the meter data. In this tutorial, I am going to measure DC current using Acs712 Hall Effect-Based Linear Current Sensor and arduino uno. Acs712 can measure current precisely and accurately if properly managed. I have gone through various blogs on internet about interfacing acs712 current sensor with arduino and other microcontrollers. I found that all of them ar Precise voltage measurement with the Arduino board. The Arduino range of microcontrollers provides analog inputs that can be used to measure voltage. We can use this to build a voltmeter. The analogRead() function reads the voltage and converts it to a number between 0 and 1023
#include esp_gatts_api.h # define GATTS_TAG EGTeachersButton // Prepended to all logging output # define GATTS_CHAR_VAL_LEN_MAX 22 // maximum length in bytes of a characteristic's value. TODO: find out how to determine this value? /* Number of services, characteristics and descriptors used in ble_server.c. * Needs to be equal to the size of the gatts_service, gatts_char and gatts_descr. ESPRESSIF-ESP32 240MHz Xtensa® single-/dual-core 32-bit LX6 microprocessor. FLASH. QSPI flash 4MB. SRAM . 520 kB SRAM. Button. Reset. USB to TTL. CP2104. Modular interface. UART、SPI、SDIO、I2C、LED PWM、TV PWM、I2S、IRGPIO、ADC、capacitor touch sensor、DACLNA pre-amplifier. Display. IPS ST7789V 1.14 Inch. Working voltage. 2.7V-4.2V.
can measure voltage, current, power, energy, frequency and calculates the electricity bill of the house. It measures the voltage above 46V and the power measurement is limited to 1200W. The voltage measurement is satisfactory in power system application but there may be a need of measuring higher power consumption. On the other hand, some researchers have made different efforts regarding. . The TI INA226 is a voltage and current monitor designed for voltages up to 36v. In Espruino, the INA226 module (About Modules) can be used to interface to it.. There is also an Espruino module for the INA219.. You can buy (see below) breakout board containing the INA226 along with a shunt resistor pre-wired Quick reference for the ESP32 Note that, when using the default configuration, input voltages on the ADC pin must be between 0.0v and 1.0v (anything above 1.0v will just read as 4095). Attenuation must be applied in order to increase this usable voltage range. Use the machine.ADC class: from machine import ADC adc = ADC (Pin (32)) # create ADC object on ADC pin adc. read # read value, 0. ESP32 is a series of low-cost, low-power system on a chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth.The ESP32 series employs a Tensilica Xtensa LX6 microprocessor in both dual-core and single-core variations and includes built-in antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power-management modules ESP32 and freeRTOS: Many manufacturers produce SoC with freeRTOS support. Expressif included freeRTOS in its latest version ESP - IDF. There are currently two methods to program the ESP32: the ESP-IDF and the ESP32 arduino Core
The ESP32 needs an input voltage of around 3.3V, so pick a battery that delivers a voltage close to this. A LiFePO4 would be perfect since it provides 3.2V. I also tested some LIPO batteries with a voltage of 3.7V, which seems to do the trick just fine. Tip 3: Pick the right ESP32 board (single-core) Most IoT devices are relatively simple and don't require a lot of computing power. Yet the. Instructions for using NodeMCU ESP32 boards in ESPHome and a description of all their pins and uses. These pins can be used with the Analog To Digital Sensor to measure voltages. GPIO2: This pin is connected to the blue LED on the board as seen in the picture above. It also supports the touch pad binary sensor as do the other pins marked touch in the above image. 5V is connected to the 5V.
Minimalist ESP (without voltage regulator) to lithium thionylchloride battery (3.6V 2600mAh); One measurement per hour -> lifetime 1.25 years WeMos D1 mini to 3x AA battery (2500mAh); One measurement per hour -> lifetime 0.75 years WeMos D1 mini to 3x AA battery (2500mAh); A measurement every 10 minutes -> lifetime 70 day More than 200 ESP32 arduino tutorials , including esp32 micropython tutorials, esp32 bluetooth tutorials, easy to learn, and we will update new esp32 tutorials every month. All orders placed will be shipped out as usual, delivery times are expected to be affected due to COVID-19.Thank you for your continued support Arduino can only measure the DC input voltage of +55v, In other words, when measuring 55V, the Arduino analog pin will be at its maximum voltage of 5V so it is safe to measure within this limit. Here the resistors R2 and R1 value is set to 100000 and 10000 i.e. in the ratio of 100:10
.6-3.6V These are 3.3 volt logic pins. A voltage near 3.3 V is interpreted as a logic one while a voltage near zero volts is a logic zero. A GPIO pin should never be connected to a voltage source greater than 3.3V or less than 0V, as prompt damage to the chip may occur as the input pin substrate diodes (shown as parasitic FETs in Figure 1) conduct. There may be times when you may need to connect them. How Does This Project Measure the Battery Level? It is good to understand that batteries have what we call a level of charge. It can be understood as the amount of voltage contained in your battery. The Arduino's analog pin acts as a simple voltmeter where the voltage value is retrieved. Then, we can convert the analog value into a digital voltage value by using the ADC conversion formula. The. An ADC may also provide an isolated measurement such as an electronic device that converts an input analog voltage or current to a digital number representing the magnitude of the voltage or current. In this tutorial ADC on ESP32 discussing the ADC operations in ESP32. Not every pin in ESP32 has the ability to do analog to digital conversion. In ESP32 there are some pins for ADC. When the operation voltage is reduced, the power consumption is also reduced (P=V*I). But if you want to reduce the operation voltage you have also to reduce the clock speed, that we already did in the previous section. The dependency between the operation voltage and the clock speed can be found in the datasheet of the Arduino microcontrollers.
The ESP32 ADC can also be configured with 9 to 12-bit resolution, for input voltage up to 3.3v. I was expecting 3.3v would be less noisy than 5v as it is further regulated from the supply voltage of 5v from USB, and 3.3v over 4095 ADC steps at 12-bit resolution would provide better precision than Arduino as well. So ESP32 seems to be perfect for my project The voltage divider decreases the voltage being measured to within the range of the Arduino analog inputs. Code in the Arduino sketch is then used to compute the actual voltage being measured. The analog sensor on the Arduino board senses the voltage on the analog pin and converts it into a digital format that can be processed by the microcontroller. Here, we are feeding the input voltage to.
Further, when the battery voltage drops to 3V (which is the safe margin to discharge LiPo batteries), the readout of the ESP.getVcc() is 3.106V. We can use this value to trigger a deep sleep to. . At its heart, there's a dual-core or single-core Tensilica Xtensa LX6 microprocessor with a clock rate of up to 240 MHz. ESP32 is highly integrated with built-in antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power. If the voltages fall within the defined levels, then the receivers are able to correctly detect the data that is being transmitted, or the state of the other lines. If the lines fall outside the required limits, then there can be uncertainty and data errors. RS 232 voltage levels. In order that the RS 232 transmitters and receivers can be designed to a common standard, it is necessary to.
ESP32-CAM Module Overview The ESP32-CAM has a very competitive small-size camera module that can operate independently as a minimum system with a footprint of only 27*40.5*4.5mm and a deep sleep current of up to 6mA. ESP-32CAM can be widely used in various IoT applications. It is suitable for home smart devices, industrial wireless control, wireless monitoring, QR wireless identification. In this tutorial, I will mainly focus on the analog to digital conversion of the amplifier's output voltage. ESP32 has two inbuilt AD C: ADC1 and ADC2 each with eight channels, but for.
It is also possible to use sensor to measure water level. Schematics and more details could be found od HARDWARIO Developers portal. Step 1: Connect Soil Sensor to Arduino. Soil Sensor can work with voltages from 3 to 5 V so you can use 3 or 5 V Arduino. It is using 1-Wire so your data pin must have 4.7 kOhms pull-up resistor to VCC pin Instead of an input, ADC pin can be used to measure supply voltage of the ESP module (this reading in not 100% accurate). To enable ADC_VCC feature you need to compile your own build: If you enable ADC_VCC you cannot use the pin as analog input anymore. user_config_override.h flag: // -- Internal Analog input -----#define USE_ADC_VCC // Display Vcc in Power status. Supply voltage is published. The ESP32 records and posts the signal strength of the wireless network that it is connected to. Press a button on the board to take three measurements of the wireless network signal strength and post the average result to a ThingSpeak channel. The device also posts a counter value so you can track measurements Constant voltage source is designed using voltage divider network made from resistor (R2) and variable resistor (VR1), adjust variable resistor so that output voltage must equal to voltage at minimum temperature you are going to measure (say 0 0 C, at 0 0 C voltage from PT100 = 0.4545V). Same as above we are using voltage follower circuit in order to avoid loading effect. The output from. PZEM-004T V3.0 or Version 3.0 is the upgraded version of energy meter. PZEM004T V3 measures the voltage, current, power, energy, frequency, Power factor. Download library, arduino code for arduino Uno, nano, nodemcu and esp32
Bus voltage is the measurement from this pin to ground. IN+3 2 Analog input Connect to supply side of the channel 3 shunt resistor. PV 10 Digital output Power valid alert; open-drain output. SCL 6 Digital input Serial bus clock line; open-drain input. SDA 7 Digital I/O Serial bus data line; open-drain input/output. TC 13 Digital output Timing control alert; open-drain output. VPU 16 Analog. The analog input of the WeMos module can measure voltages between 0 and 3.3V. The values that can be read out are between 0 and 1024. Our Li-Po battery is 4.2 or even sometimes 4.5 volts on full charge so if we would directly connect it to the analog port it would destroy the ESP chip on the board. So we need to create a voltage divider circuit to drop the voltage that is send to that input to. r2.pin2 connect to somewhere close to -3v(voltage going to measure). so negative voltage = r1.pin2 v - (6v - r1.pin2 v) Top. jimmo Posts: 2005 Joined: Tue Aug 08, 2017 1:57 am Location: Sydney, Australia. Re: ADC measure negative voltage?? Post by jimmo » Wed Jun 26, 2019 12:18 am starter111 wrote: ↑ Tue Jun 25, 2019 8:36 pm. so negative voltage = r1.pin2 v - (6v - r1.pin2 v) Intuitively. This means that it will map input voltages between 0 and the operating voltage(5V or 3.3V) into integer values between 0 and 1023. On an Arduino UNO, for example, this yields a resolution between readings of: 5 volts / 1024 units or, 0.0049 volts (4.9 mV) per unit. See the table below for the usable pins, operating voltage and maximum resolution for some Arduino boards. The input range can be.
Voltage Register GND VBUS ADC V I A0 A1 Alert SDA SCL C 0.1 F BYPASS m High-Side Shunt Low-Side Shunt Load Alert Register VS (Supply Voltage) Power Supply (0 V to 36 V) V IN+ V IN! Product Folder Sample & Buy Technical Documents Tools & Software Support & Community Reference Design INA226 SBOS547A -JUNE 2011-REVISED AUGUST 2015 INA226 High-Side or Low-Side Measurement, Bi-Directional. A precision amplifier measures the voltage across the 0.1 ohm, 1% sense resistor. Since the amplifier maximum input difference is ±320mV this means it can measure up to ±3.2 Amps. With the internal 12 bit ADC, the resolution at ±3.2A range is 0.8mA. With the internal gain set at the minimum of div8, the max current is ±400mA and the resolution is 0.1mA. Advanced hackers can remove the 0.1. Hello, ODROID-GO. To celebrate ODROID's 10th anniversary, we present the ODROID-GO Game Kit!It includes a special anniversary board with all the parts to put together your own game kit and see the workings behind such a device All 3 are calibrated different to output the millivolt voltage reading in proportional to these different units of measurement. The LM335 sensor outputs 10mV/°K. So if the LM335 is giving an output reading of 2.943 (which is 2943mV), then this is equivalent to a temperature of 294.3° Kelvin. All you have to do is take the output reading and divide it by 10 in order to get the temperature. The Wemos D1 Mini is based on an ESP8266 (model ESP-12x), so it has an analog input that can be used to monitor the charge level of the battery. In the previous tutorial, we saw how to calculate the battery voltage theoretically using a divider bridge. Here we will use a simpler method
To display the measured voltage, we will use a liquid crystal display (LCD) that has two lines of 16 characters. LCDs are widely used to display data by devices such as calculators, microwave ovens, and many other electrical appliances. This project will also show you how to measure voltages above the reference voltage by using a voltage divider. Experiment 1. In this experiment, we will make. The secondary measurement voltage can be scaled according to the turns ratio between the primary and secondary windings. This measurement method is considered l ossless because the circuit cu rrent passes through the copper windings with very little resistive losses (Fig. 2). However, a small amount of power is lost due to transformer losses from the burden resistor, core losses, and. Temperature measurement on battery-operated devices The power supply voltage applied to the microcontroller is subject to change on devices directly powered from a battery. The value converted by the ADC follows the drift of the battery voltage if the ADC reference voltage is tied to V DDA, which is the case for devices in low pin-count. In other words, it only takes 16 ms for the average filter to get 16 new measurements but it takes 1.6 seconds (16 x 100 ms) for the running average to get 16 new measurements. So it responds to changes more slowly. And you can see that in the picture below. The grey line is the same raw temperature measurement as before. The running average is shown in blue
Connect the voltage to be measured to the screw terminal of the Voltage Sensor, connected the output of the voltage divider to the Arduino. That's it. After interfacing the Voltage Sensor with Arduino, you can either view the results on the serial monitor of the Arduino IDE or on a 16×2 LCD Display. I have gone with the LCD Display Used to measure analog voltage in the range of 0-3.3V. GPIO Pins. GPIO1 to GPIO16. NodeMCU has 16 general purpose input-output pins on its board. SPI Pins. SD1, CMD, SD0, CLK . NodeMCU has four pins available for SPI communication. UART Pins. TXD0, RXD0, TXD2, RXD2. NodeMCU has two UART interfaces, UART0 (RXD0 & TXD0) and UART1 (RXD1 & TXD1). UART1 is used to upload the firmware/program. I2C. Read the Docs v: latest . Versions latest Downloads On Read the Docs Project Home Builds Free document hosting provided by Read the Docs.Read the Docs Both measured voltages are visible as two spikes in the histograms. Figure 8 shows the histograms of the five tests: AnalogRead function, free running at ÷128, ÷64, ÷32 and ÷16. The measured values of the first voltage (ADC value 511) doesn't deviate from the previous noise test. So the measurement are still accurate. The surrounding bins are very small what means that the noise level didn.