This is why almost all microcontrollers are featured with the ADC module. The TS100 has an op-amp setup to read the small voltage from the thermocouple (U1). - crasic Dec 2. voltage doublers and full bridges. So ADC has a resolution of 5mV. The STM32 Power Shield (X-NUCLEO-LPM01A) launching today is ST’s most accurate ultra-low power monitoring board for IoT (Internet of Things) devices. bluetooth, nRF51822. 3V output signal. They are used in measurement of both AC and DC voltages. 1% 0 1 Rw1 Rw2 Rw3 Rw4 PSoC The current path is shown by the blue line, and voltage measurement paths are shown in red. the input-voltage range of the ADC. An ADC measures voltage on a pin and translates it to a number. This voltage is the analog voltage that you're reading as an input. Then, I assume you know. Figure 2 is the DS18B20 connection diagram, one pin connected to the +3. AN_180 FT232H MPSSE Example - USB Current Meter using the SPI Interface Rev 1. Deciding which channel to measure at a given time is quite complicated: we can't measure a channel if the brightness PWM (the slow one) has turned it off, we need at least two measures before we can trust the ADC reading, and obviously we need to circle between all the channels regularly. 2 million samples per second. Vref voltage depending on the version of the chip can be Vref+ or Vdda. Imagine all of the things you could do with all of these senses!! In this video, we will investigate the function of the ADC (Analog to Digital Converter). As mentioned before, since we are assuming a linear behavior for the ESP32 ADC and since the non-linearity is not corrected in the APIs, the measured values are not very accurate and can be improved. According to the datasheet of ESP8266, TOUT (ADC pin of ESP8266) pin must be dangled (floating) while measuring the power supply voltage through ADC. 4 embedded reference voltage) V_REFINT is in the range [1. ATMEGA328, the micro controller used in Arduino UNO has 10 bit ADC and 5V input range this means that 5V input signal will be converted to digital value of 1023. 0, Mains Powered ADC-20 & TERM. convert "property" to. The range of GPIO port voltage is 0 - 1. Using a timer, the injected conversion mode can thus be implemented to delay the ADC measurements to after the transistor switching. - STM32™'s ADC modes and their applications. In Galileo/Edison, the reference voltage is set 5V via the shield and the ADC is of 10 bit resolution and hence the maximum value output by the ADC is 1023 (10 bit ADC; 2^10=1024). The only way is to digitize or simply speaking to convert analog in to digital. so to solve this problem we can use differenceamplifier. The Raspberry Pi requires extra steps. We shall define the units next. It will cover the main features of this block, which is used to convert the external analog voltage-like sensor outputs to digital values for further processing in the digital domain. 0 or later and ensure you are using the latest version of the STM32 BSP. Enables the ADC clock and switches on the ADC. We will interface a small potentiometer to STM32 Blue Pill board and supply a varying voltage to an Analog pin, read the voltage and display it on the 16x2 LCD screen. If you prefer the 1M to measure the voltage, you can also use 1M and 33k. In the table we find that those needs 1. So, the battery I need to measure is a 4s lithium ion, which means max voltage is ~16. It is known that on-chip passive charge sharing suffers from poor linearity due to the unregulated reference voltage during bit trials. For the 12-bit ADC of the STM32, that would be Vref / 4096. In addition, the reference voltage is often a non-standard value (like 100mV or 409. 264 of esp8266 adc range of 0 - 1 volts. So to measure an analog quantity with 8051 microcontroller we need an external device which can measure analog quantity and pass it to 8051 microcontroller. If you wish to measure higher voltages, you will need to resort to another means. Current does not flow through wire resistances Rw3 and Rw4, because of the high-input impedance of the ADC. For more theory behind, please take a look at the previous related article: ESP8266 – Internal ADC. Applications like such demand the use of dual ADC mode. The differential configuration of the op amp works as a four-wire measuring circuit similar to those used in many DMMs. so we measure the voltage drop across a resistor then use an op-amp to scale this up to 0-5V for the ADC there are current sensor available in market to measure current let's take example if I use one current sensor or circuit that can measure current between 0 to 30 A. 3 V 1 0 n F 0 0 F 0 47pF(NA) 100nF 100nF 100nF 1uF/10V 100nF 1uF/10V 100nF NA 1uF/10V 27pF 27pF 10pF 10pF 2. One bit of a -bit ADC always represents Vref / 2^n. Vref voltage depending on the version of the chip can be Vref+ or Vdda. 7 female-female jumper wires preferably two pairs in the same, the rest in different colors 2 Pieces of wire in different colors to measure the voltage, approx. 01 V on VBAT and 4. Obviously this is not enough to measure LiPo battery voltage which ranges from 4. This mode can be used for the measurement of a voltage level to decide if the system can be started or not. 3 * (10/66) = 0. Measure Voltage, Current, and More with an STM32-Based Open Source Multimeter Hackaday user Martin needed more multimeters in his lab, and instead of buying more, he decided to build his own using about $10 worth of…. There are essentially two methods to measure voltages: ground referenced and differential. 3V output signal. The 12-bit ADC is a successive approximation analog-to-digital converter. I am using sbRIO 9627 for voltage measurement using the on-board 16 bit ADC which have 8 differential channels as input. Back to Package. ,i am using adc, with an input of 9. Apart from the basic measurement there are a number of other functions that are required and these all take time. In this case, do not start the system. The input current from the 10 V source will be about 10 µA (10 V/10 MΩ). On NUCLEO_L031K6 we use the ADC pins: PA1 (TempRel), PA3 (PhotoRes),. The peripheral driver library should make it relatively easy to use. Completed bench test using digital volt meter to measure motor on and off analog readings 0. They only understand '0' and '1' values. Measuring battery voltage with Nordic nRF51x devices. In the case of measuring the voltage of the battery supplying the STM32, your unknown is the VDA, and your VUNKNOWN is the 1. Example Software Overview. ATMEGA328, the micro controller used in Arduino UNO has 10 bit ADC and 5V input range this means that 5V input signal will be converted to digital value of 1023. The ADC on an STM32 microcontroller, for example, can sample at rates up to 1 Msample/s. Using a timer, the injected conversion mode can thus be implemented to delay the ADC measurements to after the transistor switching. This means a dc current can be indirectly measured by a microcontroller’s ADC channel by first converting the current into voltage. 35 V on VCOM, - not equal. 16 external channels, connected to IO pins 3 internal channels Vbat Voltage on battery pin for RTC Temp sensor unusable for measure temp,only for measure difference in temperature because it can fail up to 45°C Vref Voltage reference for ADC Below is table. ) The input signal is usually an analog voltage, and the output is a binary number. The TS100 has an op-amp setup to read the small voltage from the thermocouple (U1). Vref+ is set to Vdd. View online or download St STM32 Nucleo User Manual. You can plug an analog sensor directly into an Arduino using the analog ADC pins. I´ve configured the ADC to work with an 1uS time conversion. November 2019 AN2834 Rev 4 1/50 1 AN2834 Application note How to get the best ADC accuracy in STM32 microcontrollers Introduction STM32 microcontrollers embed advanced 12-bit or 16-bit ADCs (depending on the device). Please help as to how i can measure the battery voltage ? It all comes down to how we can set a reference voltage for ADC measurement. The adcDCpropab library’s adc_in function returns the actual numbers the A/D converter sends the Propeller chip. DC Voltage Measurement. so to solve this problem we can use differenceamplifier. 3 mV per step. Arduino ADS1115 Analog to Digital Converter Simple Tutorial. That could be done instantly with a cheap 8 bit ADC. The Analog to Digital Converter (ADC) is used to convert an analog voltage (a voltage that vary continuously within a known range) to a 10-bit digital value. PE3 is the temperature of the external input pin. The biggest problem with this approach is the heinous amount of CPU time doing Software measurement. I am trying to measure battery voltage on the PCB using one of the ADC channels of the microcontroller. You can use the ADC of the microcontroller to sample such signals, so that the signals can be converted to the digital values. STM32F4xx MCUs have up to 3 ADCs of which every has 19 channels. the mean) between 6V and the voltage you're measuring. If the current returns through ground, you can use a simple shunt resistor to convert the current into a voltage before measuring with the ADC. And VCOM voltage == VBAT if battery in rest state ( not charging ). In this lecture first, we will learn about the interfacing of potentiomter with MSP430. I have to read the battery voltage that is being used to power the stm32-l152re chip. One just makes a LED blinking, another samples voltage on VRx and VRyand read SW status and the last one (the main()) prints data on a sequential stream. All informations about performance related to cost, acquisition speed and real bit resolution. 168 release. hold value during conversion. Thus, the maximum value (when the input voltage equals 3. Optimizing RCAL,RTIA,CTIA and DAC voltage of ADuCM350 for 4-Wire Measurement. If it hits some value I'll have to set PAD to 1 or 0 but this is not a problem. You must take into account the measured signal's analog characteristics to find the best sample rate. It contains the ADC's DONE bit and the result of the most recent conversion. Measuring VBAT sets the ADC_CCR_VBATE bit in ADC->CCR, and there doesn't appear to be a way with the HAL to clear it. Please suggest a method to measure 3. You'll normally get best results by using an external Vref, and to make sure that this voltage is properly filtered. There are 343 patches in this series, all will be posted as a response to this one. Posts about stm32 written by satish. 5 and 13 cycles for a total of 14. You just have some idea of ADC's of micro-controller. 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). In this tutorial, we will be measuring DC voltage and current in the circuit. Read about 'Measurement by ADC of STM32' on element14. You'll normally get best results by using an external Vref, and to make sure that this voltage is properly filtered. Im new in ANSI C @STM32 but I tried to measure a Voltage (~12V) with a voltage divider and a Analog GPIO. All informations about performance related to cost, acquisition speed and real bit resolution. These ADC circuits can be found as an individual ADC ICs by themselves or embedded into a microcontroller. I applied external reference of 3V. When measured with the ADC, would have to obtain half of the supply voltage. This STM32 microcontroller has a 12-bit ADC with 16 channels. I have to read the battery voltage that is being used to power the stm32-l152re chip. When the STM32 board is powered via USB cable then the operating voltage is 3. It is cleared. By measuring the voltage you can quickly tell when you’re heading below 3. one pin connected t o the +3. That value is calculated as the band-gap voltage (in mV) multiplied by 1023. The Arduino has several analog input pins that connect to an analog-to-digital converter (ADC) inside the Arduino. ) Bits[15-6]: BRESULT- When DONE is 1, this contains a binary fraction representing the voltage on Ain pin selected by the SEL field, divided by the voltage on Vref pin, V/Vref. Amongst them is an internal, factory-calibrated temperature sensor and a supply voltage sensor (that specifically senses VDDA, the analog supply voltage rail) connect to channels 16 and 17 of the internal ADC. The AD input is calculated through the oscilloscope, in which you see a sinusoid, which is not 110 (but it is well formed). Back to Package. It’s in the math: how to convert an ADC code to a voltage (part 1) Many newcomers to analog-to-digital converters (ADCs) wonder how to convert their ADC code to a voltage. One bit of a -bit ADC always represents Vref / 2^n. And the ADC, microcontroller, and LCD need to have to same ground unless a complicated isolation scheme, probably optical, is employed. 3 V 1 0 n F 0 0 F 0 47pF(NA) 100nF 100nF 100nF 1uF/10V 100nF 1uF/10V 100nF NA 1uF/10V 27pF 27pF 10pF 10pF 2. x 6 digit numeric Units: lb, kg (primary), oz, g (LCD only) Accuracy Class: 5,000 e Resolution: 120,000 dd industrial; 10,000 dd HB44 Excitation Voltage: 5V DC Largest Output Current: 120 mA Excitation Circuit: 5 VCD, 4 wire connections Load Cell: 6 load cells of 350 Ω maximum Load Cell Excitation: 5 ± 0. However when I try to create the gpio object. PIC ADC can convert voltages ranging between 0 and Vdd, which, in case of our MCU, is 3. Browse our latest Data Loggers offers. Then, I assume you know. 1 volts to 1 volt. 5VDC Display Resolution: 30,000; ADC: 2,000,000. I have my source supplying battery connected to a voltage divider (since the board is powered by 3. average measurement technique works well till input is pure sine wave but as soon as. Google ADC. Example Software Overview. You could imagine a multitude of applications based on the STM32 ADC features. Robertson, Phillips, and the History of the Screwdriver - Duration: 16:25. In this tutorial, we will be measuring DC voltage and current in the circuit. 5V and the Arduino ADC. I am trying to measure battery voltage using the ADC pin which is listed as gpio2 on the data sheet. 这时如果芯片内含有3个adc. Multi-slope integral technique is also employed to enhance measurement accuracy. the mean) between 6V and the voltage you're measuring. Usually shunt resistors are thick film metal plate low resistance (1mΩ – 100mΩ) so as to minimize power consumption and to allow power dissipation. With the 10nF parallel to the 33k, the ADC conversion is probably still accurate enough. This doc shows how to use nRF51x microcontrollers to read input voltage without using an analog input. In this tutorial I will talk about ADC (Analog to Digital Converter). In its basic implementation, the dual-slope converter, the unknown input voltage is applied to the input of the integrator and allowed to ramp for a fixed time period (the run-up period). 2V, which I like to think Douglas Adams would appreciate, but most STM32s have a maximum voltage of 3. When the STM32 board is powered via USB cable then the operating voltage is 3. 0, 01/2016 2 Freescale Semiconductor, Inc. On NUCLEO_L031K6 we use the ADC pins: PA1 (TempRel), PA3 (PhotoRes),. You just have some idea of ADC’s of micro-controller. 3 V battery divided down to the bandgap range using a 56k and 10k resistors, so the voltage at the ADC input is 3. (One might connect Vdda to Vref, making Vdda to Vref). ADC to measure battery voltage zcmm over 4 years ago setup, I have a 3. ) Bit[31]: DONE- This bit is set to 1 when an A/D conversion completes. This means a dc current can be indirectly measured by a microcontroller's ADC channel by first converting the current into voltage. Following the standard color convention,red wire serves as the positive connection lead while black one is the common or negative lead. convert analog value to digital #. I figured, that i will use ADC injected mode for this. You can check a higher voltage, to do this, you setup a voltage divider with resistors and feed the divided voltage into the ADC. age to the ADC, the number of counts, and the coil's resistance. 1 volts to 1 volt. ) The input signal is usually an analog voltage, and the output is a binary number. In the case of measuring the voltage of the battery supplying the STM32, your unknown is the VDA, and your VUNKNOWN is the 1. In this tutorial we will learn how to use ADC in ARM7-LPC2148 by supplying a varying voltage to an Analog pin and display it on the 16x2 LCD screen after analog to digital conversion. To solve this problem most modern MCUs have an ADC unit. STM32 is a microcontroller family from ST with a 32-bit ARM Cortex-M0/M3/M4 CPU. You can check a higher voltage, to do this, you setup a voltage divider with resistors and feed the divided voltage into the ADC. UPGRADE YOUR BROWSER We have detected your current browser version is not the latest one. Introduction To achieve higher accuracy and repeatability of measured sensor impedance using ADuCM350, the RCAL, RTIA , CTIA and the DAC output voltage during the measurement needs to be optimized. An ADC always uses a reference voltage to make it's conversion. The simplest way of doing this is to place a resistance in series with the current path and measure the voltage drop across it. The other problem I realized is that, there is voltage on the multisense pin, even when there is no load on the output. It explains how to design an application to reach the requested precision and provides workarounds. I still have to repeat the measurements with various supply voltages. Using this value, a measurement of the Vrefint channel, and some math, one can convert other channels from ADC counts to millivolts. Measure the voltage level of the battery before starting the system: if the battery has a low level, the “low battery” message appears. ADC to measure larger voltage from ground They plug right into the GPIO headers on the Pi and even come with some python libraries for reading them. 1 volts? A: Theoretically yes, but since a typical AVR cuts out at either 2. But we experimented a bit with the internal voltage reference (V_REFINT) of the ADC peripheral. by the ADC peripheral module. Read about 'measure ac voltage and current using aurdino' on element14. They only understand '0' and '1' values. But I will give you a method through which you can do this job just like 1 2 3. The circuit uses a 230V AC Transformer to 9V (RMS) and makes use of a voltage divider. This doc shows how to use nRF51x microcontrollers to read input voltage without using an analog input. 015) / 1024. Read about 'Measurement by ADC of STM32' on element14. They're called ADCs. Typical Voltage Source Connection To ADC Input 39. Measure Voltage, Current, and More with an STM32-Based Open Source Multimeter Hackaday user Martin needed more multimeters in his lab, and instead of buying more, he decided to build his own using about $10 worth of…. STM32F4xx MCUs have up to 3 ADCs of which every has 19 channels. Reference Point Methods. 1 - refer to the readme inside of the package. The AD input is calculated through the oscilloscope, in which you see a sinusoid, which is not 110 (but it is well formed). By adjusting gain of difference amplifier we can reduce voltage lower than 5 volts. So ADC has a resolution of 5mV. 2V and rated voltage for 110-003 is 1. Currently I'm working with a STM32 microcontroller which ADC is connected to a buffer, exactly the same way you show in the last picture, but in the board the capacitance is far from the ADC. If no internal reference is present or it's not accurate enough, you can connect an external precision reference to an ADC input and use it for the correction. However when I try to create the gpio object. No matter how I change the voltage, the sampling results are the same. Intuitively, with two 100k resistors, your ADC pin will be at the midpoint (i. The ADC needs to do two things to provide a conversion: Sample and Hold and SAR Conversion. The math becomes a bit more complicated with that but it will work. FRDM-K20D50M - ADC Voltage Measurement with processor expert. For a low voltage of 3 volts these resistors would give 0. If the current returns through ground, you can use a simple shunt resistor to convert the current into a voltage before measuring with the ADC. With the ADC, you can sense the environment (light, sound, distance, gravity, acceleration, rotation, smell, gasses, other particles and even feeling through pressure). It's in the math: how to convert an ADC code to a voltage (part 1) Many newcomers to analog-to-digital converters (ADCs) wonder how to convert their ADC code to a voltage. For example if input is more than 2. 5-V DC output level shift. In this example we will use the ADC to monitor the main voltage. 5V across each resistor. The total supplied voltage is the complete voltage is supplied to the circuit. The differential configuration of the op amp works as a four-wire measuring circuit similar to those used in many DMMs. The only way is to digitize or simply speaking to convert analog in to digital. Using the Waveshare ADC board with a RaspPi 3 to monitor the current driving a DC brushless motor. what are you thinking of trying to measure?? am i correct that you are not trying to measure 5A of current ? hopefully ? i have used a 1 ohm resistor on many occasions to measure current -in the 0 to 200mA range. Run the script without the -debug parameter. Figure 2 illustrates an example of the ADC being used with external divider resistors to achieve the measurement of a ±10 V input signal. To measure a three-phase power, ADC1 and ADC2 are used with 6 channels (3 channels for the voltage and 3 channels for the current). In this mode, ADC does one conversion and then stops. Microcontrollers are meant to deal with digital information. I need to measure voltage on 4 channels during each PWM period. So far as I know, my ADC is functioning perfectly, and I am able to get a reading from the desired analog input. R = Vref/Imax. Twice the voltage is developed across RL3, but this is a common-mode voltage, so it does not introduce errors. ) The input signal is usually an analog voltage, and the output is a binary number. The ADC clock must not exceed 36 MHz for Vdd > 2. This reference voltage is equal to supply voltage to Vdd pin, which is around 3V for this STM32F0 Discovery kit. produce convenient. Before you begin, install VisualGDB 5. This could be a voltage, current, resistance, temperature, light and so on. Twice the voltage is developed across RL3, but this is a common-mode voltage, so it does not introduce errors. This is quite welcome if one wants to monitor the supply (battery) voltage with simple divider. I am using sbRIO 9627 for voltage measurement using the on-board 16 bit ADC which have 8 differential channels as input. An analog to digital converter (ADC) converts an analog signal into digital form, shown in Figure 14. Because it uses may ADC readings the result is usually better than 10 Bit resolution, more like 12-16 bits if the sampling window is close to an multiple of the signal period. AC Voltage Measurement using Atmel AVR Micro-Controllers. • This ADC mode can be implemented to monitor a battery voltage, the measurement and regulation. 8 road 24-bit ADC module mounted TI ADS1256IDB,minimum Power consumption,high precision ADC chips and 2. January 2014 DocID025743 Rev 1 1/99. In this method, Controller continuously poll the ADC device and when the data conversion is complete, it can be read using HAL_ADC_Getvalue() function. You'll normally get best results by using an external Vref, and to make sure that this voltage is properly filtered. Home Labs Stories A cheap solar powered stm32 Arduino node. over range of interest. 3 V) is 4095 (0b111111111111). So far as I know, my ADC is functioning perfectly, and I am able to get a reading from the desired analog input. The peripheral driver library should make it relatively easy to use. Understanding Ratiometric Conversions 9 Conclusion A voltage reference has a direct influence on the accuracy of output that is possible with an ADC. ) The input signal is usually an analog voltage, and the output is a binary number. And the ADC, microcontroller, and LCD need to have to same ground unless a complicated isolation scheme, probably optical, is employed. The range of GPIO port voltage is 0 - 1. convert analog value to digital #. 4) What i intend about floating is this. convert “property” to. 6) 2, or about 0. 3 V, which is the reference voltage (AFAIK) of the ESP32 board I am using. Google ADC. STM32 micros have an internal bandgap voltage reference source. Currently I'm working with a STM32 microcontroller which ADC is connected to a buffer, exactly the same way you show in the last picture, but in the board the capacitance is far from the ADC. 264 of esp8266 adc range of 0 - 1 volts. The goal is to perform a ratiometric measurement such that the VREF source voltage to the divider is the same as the reference to the ADC used to measure the voltage at VT. But we experimented a bit with the internal voltage reference (V_REFINT) of the ADC peripheral. In order to set up your board for conversion, first connect the wire (potentiometer, etc. adc battery battery charger bottom-up C charge controller Code Quality critical section development dump load duty cycle energy harvester FreeRTOS gpio Guidelines high-side linux lock low-side low-side switching mosfet mutex object-orientation power mosfet process pwm queue relay scrum semaphore sensor board signal solar energy stm32 stm32. AD7691 18-bit SAR ADC was chosen. This • Channel-Isolated Current Inputs and Group. You can simply drop the current across a know resistance to generate the required voltage range on the input. ATMEGA328, the micro controller used in Arduino UNO has 10 bit ADC and 5V input range this means that 5V input signal will be converted to digital value of 1023. In this video, I have demonstrated how to create a simple project in CubeMX for an ADC application. Currently I'm working with a STM32 microcontroller which ADC is connected to a buffer, exactly the same way you show in the last picture, but in the board the capacitance is far from the ADC. You just have some idea of ADC’s of micro-controller. 3V range of the onboard ADC of the STM32. I applied external reference of 3V. In this tutorial I will talk about ADC (Analog to Digital Converter). I comparing the ADC from this µc. I don't know if this is the reason why I have to put a delay before reading the ADC (equivalent to 10 times RC) to get the same value as measured with the. Understanding Ratiometric Conversions 9 Conclusion A voltage reference has a direct influence on the accuracy of output that is possible with an ADC. This note will start by explaining how to correctly power and wire the microcontroller for sensing voltage. In this case, do not start the system. There are essentially two methods to measure voltages: ground referenced and differential. The ADC is configured to measure 0- to 5-V unipolar. By converting from the analog world to the digital world, we can begin to use electronics to interface to the analog world around us. Extensive experience in various hardware fields, including: • Power supply design (low voltage, medium voltage, and high voltage) • Battery charging and management • IoT. 1mm thickness should be fine. Example Software Overview. There are numerous resources all over the web which solve this puzzle. As a software guy @TomasBy you should understand that this will make your life hell dealing with timing details when you can just use a jelly bean ADC and save your sanity. 2 million samples per second. So, what if i connect the VBAT connector to a stm32 ADC pin through a voltage divider? Is there is a possibility that I will damage quadcopter?. convert analog value to digital #. The other option here is to have the divider in place, but use a zener diode to clamp the voltage at the ADC pin to prevent damage - ie the zener will clamp before the ESD diodes within the STM32 start conducting. Re: Battery Voltage Measurements using ADC Post by onehorse » Tue Dec 20, 2016 6:26 pm I use a 27 kOhm + 100 kOhm voltage divider to bring the 4. This is the reference design and main target board for MicroPython. So, what if i connect the VBAT connector to a stm32 ADC pin through a voltage divider? Is there is a possibility that I will damage quadcopter?. A CHEAP SOLAR POWERED STM32 ARDUINO NODE by Tom Vijlbrief. Unfortunately, when using a constant voltage excitation configuration, because of the voltage divider effect, R1 and R 4 still creates errors in the RTD measurement unless the ADC system has the ability to measure the voltage at the excitation voltage output (V). 1V resolution should be easy to achieve and 50mV resolution should be possible. The internal voltage reference is not used by the ADC but can be used as a comparator for zero crossing detection. YL-40 PFC8591 ADC/DAC module; Analog voltage sensor, preferably with 3. Note that node B is grounded, so the signal is present on node A. To solve this problem most modern MCUs have an ADC unit. I am trying to measure battery voltage using the ADC pin which is listed as gpio2 on the data sheet. Ammeter click carries MCP3201, a 12-bit ADC. We shall define the units next.