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7

Using the 1.1V internal analog reference to measure a draining VCC source by using a voltage divider on it You could indeed use a voltage divider, and measure a scaled-down Vcc against the internal 1.1 V reference. This is, however, not what the code you posted is doing. It is instead measuring the internal reference against Vcc, as stated in the comment ...


5

There is a basic error in your methodology which leads to incorrect conclusions. You cannot determine what is going on from just two data points. Instead you need far more. Here is a voltage sweep from 5V to 12V with a 0.05V resolution (overkill, but the default setting for the script I use) connected to a Mega: As you can see the current steadily climes ...


5

It will not be possible for you to PWM dim your LED with that LED driver (power supply). That is a constant current driver with under/over-voltage protection. It delivers a specific amount of current (1.5A) and varies the voltage to allow that to happen. If the voltage rises too high or falls too low then there must be a fault, so it shuts the power off. ...


5

Voltage Drop Well, if you put 5V into your barrel jack, your UNO's onboard 5V regulator is going to drop that down to 3.5V or so. You must have more than 5V into the regulator to get 5V out of it. This is referred to as the regulator's "drop out" voltage. The specs for an UNO say to power it from at least 7V for that reason. As an experiment you ...


4

If anyone else is confused by this: Will it hurt your Arduino? No, this is a internal voltage reference between VCC & the 1.1v internal analog reference. Is a voltage divider necessary? Not unless you have something external of the Arduino to measure! Is the internal reference actually 1.1v? No, it seems like each pro mini I have the the 1.1v ...


3

As mentioned in the comments, you cannot power your robot from a 9V block battery. These are made for low power projects (like a smoke detector) and cannot provide enough current to drive even only the motors correctly. Using 2 of them does not really help much. You need to change to a different battery type. If you want to stay with alkalines, you could use ...


3

Late to the convo but quick comment in case anyone else reads this thread still. Arduino uses a linear regulator on Vin. In that case the “extra” voltage gets wasted. You’d get a much more efficient battery use by using a buck or boost circuit to provide it the correct 5V on the 5V pin (or usb) rather than feeding a 2S LiPo into Vin. It would work both ways ...


3

This looks like something out of an Arduino n-part “sensor kit”. It’s hard to tell because the quality of the image is not very good. My guess is, this is an analog temperature sensor, like in this link, part number 18. You can also find an example sketch there.


3

I think the answer to your question can best be summed up by one word: "Kinda". The best reasoning is the NodeMCU Lua documentation which states: Time keeping on the ESP8266 is technically quite challenging. Despite being named RTC, the RTC is not really a Real Time Clock in the normal sense of the word. While it does keep a counter ticking while ...


3

On the nodeMCU board all the 3.3v pins have continuity. That means they all do the same thing. And yes, you can apply ~3.3v to them. I have trouble with voltages under ~2.8 though, 2.5v is likely not going to work. Use a buck+boost to keep it 3.3v if needed. For cheap dc/dc converters, I strongly prefer ones with XL semi chips; clean enough to please the ...


3

To keep the same brightness, you have to keep the same duty cycle (percent of on time over off time). So to change the rate without changing the brightness, you have to increase delayMicroseconds(onTime) by the same percent you increase delay(strobeDelay). But note that as you go slower, the on time will be too long to freeze the motion you are trying to ...


2

Does the MB-102 can handle Arduino Uno, SIM900 and 3 other modules that requires 5v? You mean because the current requirements? The answer is yes and no. No, because the needed current must not flow through the Arduino. The SIM900 draws up to 2A, that current would fry the protection diode/voltage regulator on the Arduino (though you may get away with a bit ...


2

I've seen people saying something about putting the grounds of the board and the module together Yes, I believe this is what you need to do. Servo is connected by to pin 10, and the ground and power are both routed through the 5V power module which is attached to a 9V battery. From what I understand, you are wiring like this Servo 5V - 5V Power module ...


2

TL;DR: You really need to know what components you have and you need to find datasheets. In the datasheet, you find what voltage the component requires. Don't care too much about amperes in the beginning. If you get the voltage right, each component will just draw as much current as it needs. An Arduino Uno operates from 7 to 12 Volts, so 7.4 V is ok. "...


2

Please have a look at the schematics: https://cdn-learn.adafruit.com/assets/assets/000/010/774/original/adafruit_products_trinket5.png?1378223478 The USB connector uses a resistor (1500 Ohms) against the 5V net and a 3.6 Volt Z-Diode on it's (D-)-Pin. In addition to the current that is drawn by the microcontroller, this part of the circuit draws some extra ...


2

That is a perfectly legitimate use of the RESET pin. Holding the chip in reset perfectly valid. Everything in the chip will be stopped. Releasing it will start your sketch from the start again perfectly fine. The only negative point is that your switch will be pulling power through the reset pin's pullup resistor, so will waste a little power.


2

The only way to keep millis() running is sleep mode is to sleep in SLEEP_MODE_IDLE. Switching to Timer 2 would make no difference, as all timers but the watchdog are stopped in other sleep modes. The watchdog is horribly inaccurate, so you do not want to rely on it for any kind of timekeeping. I don't see much advantage to sleeping for 1 ms. Sleeping for ...


2

I would do as follows: Software: Arduino is in sleep mode every x seconds (x depending on your needs), wake up then switch on and read one sensor after the other and transmit the results or whatever you want to do. then go back to sleep Hardware: as you have 4 sensors, you can connect their outputs to the arduino analog inputs (or digital...) you will ...


2

In fact, for a project like this, you should use two Arduinos, one as SLAVE and the other as MASTER. You mentioned 4 sensors for measuring water quality, but you will have more modules such as RTC and MicroSD to store the data. So, I think you should use Slave to colect the data from sensors using the Tentacle Shield, and the other Arduino as Master, to ...


2

You can use a branded 5 V charger made for cars. You can directly connect this to 5 V pin of the Arduino. By doing this: you are protecting the Arduino from the noise as well as high voltage spikes coming from the car 12 V supply protecting yourself and others coming in contact with the Arduino or the sensors connected to the Arduino. You can also ...


2

As is described in this post from the arduino forum, There is a MOSFET switch in series with the USB connector +5V input line. If the battery booster 5V output is connected to the USB input jack, then it will automatically power the UNO whenever power is disconnected from the barrel jack, and will be automatically disconnected whenever at least 7.0V is ...


2

The official page for the Nano 33 BLE Sense mentions various things including the datasheet for the light sensor. That appears to be much more sophisticated than an LDR. According to the sensor documentation (above): Upon power-up, POR, the device initializes and immedi-ately enters the low power SLEEP state. In this operational state the internal ...


2

Instead of calling analogRead(), this sketch performs the equivalent actions by directly manipulating the hardware registers to begin a conversion, wait until the conversion is complete, and collect the converted value. Just reading the final value is accomplished by the statements: result = ADCL; result |= ADCH<<8; All of the statements following ...


2

If you buy a 30V current-limiting power supply set to limit the current to 1.5A, you should be able to use it to power your LED light through a high power logic level MOSFET. You could control the MOSFET with a PWM signal from an Arduino and use that to vary the brightness of your light. With a little googling I found an adjustable power supply with an ...


2

"Ground" is just a lump of metal and each ground "pin" is connected to it. That includes the ground connection in the barrel jack. It's all one thing. Wherever you connect your fan's ground to it's all ground. That is, as long as all grounds external to the Arduino are connected, ultimately, to the Arudino.


2

Most USB powerbanks will automatically turn off if there is not a minimum current draw to keep them turned on. The Arduino is obviously drawing current below the limit for the devices you have. A couple of options: Add some additional load to keep the powerbank on indefinitely. Of course this may waste power but that's part of the price to pay. Find a ...


2

Your idea is sound, but your implementation is flawed. First, you don't want to bother with "wake" and things like that - when the chip gets power it just starts from scratch - that's your "wake" signal. Your code will just be "Hold it on" and "Make a sound" followed by "Let it switch off". You only need one ...


1

Yes, you may connect all 3V pins together (red) and all GND pins together (black), like so: In some cases, more wires will improve the circuit. E.g. when you build the Ben Eater 8-Bit CPU, you'll find that connecting power in a ring instead of a line will reduce voltage drop by about 50%. When first reading your question, I got the impression that you ...


1

For this task you should use an extra power supply not running trough the Arduino. For this kind of setup I use PCA9865 16-channel servo dirver board cost around 5$, needs two pins only and can run all servos (strong 5V power supply provided => Amperage) simultaniously. For a max of 8 servos a 5V/2-2.5A power supply (wall wart) should be sufficient. See this ...


1

As soon as I connect up the battery, I loose the Serial Monitor connection (even though the USB cable is still connected). So I can no longer see what's going on inside the Arduino for debugging purposes. Why? How can I continue to see the Serial Monitor? Is there a way to see the serial output from somewhere other than the USB jack? Probably because ...


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