Questions tagged [arduino]

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13
votes
3answers
16k views

Measure Lithium ion battery voltage (thus remaining capacity)

What I am working with: I am running my self-made Arduino board (in the sense that I use the Arduino bootloader and code editor) at 3.3V, and powered from a Lithium ion battery, which is USB-charged ...
37
votes
5answers
132k views

How can I use a 12 V input on a digital Arduino pin?

I am creating a controller for a 12 V system using an Arduino Uno microcrontroller. For the outputs I am using a relay shield to switch the 12 V components. I have a 12 V toggle switch that turns on ...
12
votes
4answers
19k views

Thermistor control of peltier voltage with Arduino (for DSLR chill box project)

I am mildly familiar with electronics, mostly from playing around with electronics kits as a kid. That was a long time ago, though, maybe as much as 20 years ago. I am currently working on a cold or "...
12
votes
5answers
5k views

“Overclocking” an AVR

In AVR datasheets under the Electrical Characteristics section you will typically find a graph like this (this one is from the ATMega328): I've seen designs that seem to "work" but operate outside ...
52
votes
5answers
162k views

How much current can I draw from the Arduino's pins?

What's the maximum amount of current which I can draw from each of the Arduino's pins without tripping any of the internal fuses? Is there a limit per pin as well as an overall limit for the whole ...
34
votes
4answers
7k views

I2C 3.3 to 5.0 V conversion

I'm trying to interface a 3.3V I2C device to a 5V Arduino. I don't have any problem with SCL line. I can use a simple voltage divider but I have an issue with the SDA line as this is bi-directional. ...
12
votes
6answers
31k views

Need help calculating resistance for transistor base

I have 3 12VDC/40A automotive relays (datasheet) that I want to use with my Arduino. Based on the tutorial I am following (link) I need transistor, resistor, and diode. I am not an electrical engineer ...
17
votes
2answers
33k views

Input impedance of Arduino Uno analog pins?

I'm using the ACS712 hall-effect based current sensing chip on some small robotic arm motors, and reading in the analog voltage with an Arduino Uno. I've had reasonably good results, but only after ...
50
votes
7answers
83k views

How can I get my atmega328 to run for a year on batteries?

Scenario I have created a nice electronic door lock for my dorm room. It is currently an Arduino Diecimila with a servo [un]locking the door. It has a numerical keypad with 3x4 buttons and 5 LED's (2 ...
44
votes
6answers
101k views

Do I really need resistors when controlling LEDs with Arduino?

I'm just trying out Arduino Uno for the first time with 2 blinking LEDs on a breadboard. All the tutorials on the Internet seem to use a resistor. I do know the function of resistors, but does it ...
36
votes
2answers
27k views

Selecting a MOSFET for driving load from logic

I'm looking to drive a magnetic door lock from an Arduino. I've found a question about driving a solenoid from an Arduino, which includes a circuit that looks perfect for this kind of situtation: ...
19
votes
7answers
36k views

How many individual lights can an arduino control

I want to use a regular Arduino board to control LEDs - what is the most lights I can control individually from the board? Is there a tutorial on how to hook it up?
12
votes
3answers
13k views

How do I get +5v for loud noise, 0v for silence from Electret Microphone (or other components)?

I have been asking a few questions here to get to a proper one, the initial questions I asked are linked to at the end. I used Fritzing to make up some schematics of my initial thoughts, but at the ...
39
votes
6answers
156k views

What is the voltage range of a standard headphone jack from a phone?

I want to connect the output from the audio jack of an iPhone to an Arduino. What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the ...
9
votes
2answers
21k views

How to Use SFH235 IR Photodiode Correctly?

I have an SFH235 ir photo-diode (which datasheet can be found here) and only basic knowledge of electronics. I want to connect the photodiode to an Arduino (the grand-plan is to add an ir diode and ...
11
votes
6answers
4k views

Sensor for ultralow (to -85°C) freezer monitor

I am planning to build a series of Arduino-controlled temperature-reporting units for a room full of "Ultracold" -80°C freezers. (I ultimately want to convert the signal to a serial stream that will ...
4
votes
2answers
1k views

Microcontroller soft off circuit not working - why?

I was making a board with an atmega328 mcu (to be used with Arduino libraries) to do some one wire communication stuff. Since I was etching the board anyway, I decided to try and implement a simple ...
22
votes
3answers
21k views

How do I create a permanent application from something prototyped with Arduino?

Part one of a three part series on transitioning from Arduino to a plain AVR microcontroller and minimum supporting components (part two, part three) I've built up a project on my Arduino Uno to ...
8
votes
2answers
30k views

Switching 9V using a NPN transistor and an Arduino

First of all, I'd like to say I'm not an Electrical engineer so please bear with me. I haven't got a sketch for what I'm trying to achieve but hopefully I can explain it ok. I have an NPN transistor (...
6
votes
3answers
15k views

Detect car +12V using Arduino

I am looking to detect 12+V from a car wire using an Arduino. I have found the following schematic: I know how crazy automotive voltage can get so I just want to make sure the schematic I found ...
3
votes
2answers
4k views

Is it safe to use a voltage divider for Arduino and DC motor controller?

I have ordered a Dual H-Bridge 12A continuous (30A peak) Polulu motor driver shield for my upcoming (first time ever, a 1.2m long tank made of wood) robot project. I was thinking about how to supply ...
0
votes
1answer
1k views

multi channel ac dimmer for arduino

I have been looking for a simple ac dimmer circuit to use with my arduino and/or raspberry pi. I have used the TLC 5940 PWM Driver before just to control LEDs and I wanted to adapt this to controlling ...
1
vote
6answers
8k views

positive vs negative, power vs ground, flow direction

I'm getting very confused about the inconsistency where some people say ground is always negative, and some say ground is always positive. And some would say, electrons travel from the power source ...
9
votes
2answers
23k views

Hooking up multiple RGB LEDs while using a minimal number of PWM pins on an Arduino?

I currently have an anode RGB connected to the 11, 10, & 9 PWM pins on my arduino. However I would like to add 3 more LED's to my project, but I don't want to necessarily take up every single PWM ...
18
votes
3answers
96k views

Using a microphone with an Arduino

EDIT: I have been investigating in this problem for quite some time. It turns out to be a way more difficult project than I thought and not something for beginners. This requires expensive hardware (...
16
votes
6answers
25k views

How is binary converted to electrical signals?

I'm just starting off in electronics and am already fascinated. Having played with an Arduino these past few days I'm aware that binary is a representation of different voltages - such as +5V ...
2
votes
6answers
38k views

How do I burn an ATmega328 chip via Arduino UNO as ISP?

I've an ATmega328 chip (without a bootloader), and I want to burn it with my Arduino Uno as ISP, so I can have a spare ATmega328 with an Uno bootloader. I'm trying to follow the instruction in Using ...
11
votes
1answer
42k views

How to control a 12V solenoid valve with a mosfet?

I'm trying to control a 12V DC solenoid valve through a MOSFET (BS170), which receives its control signal (5V) from an Arduino microcontroller. This is the basic schematic: When I test the MOSFET, ...
9
votes
3answers
2k views

How would I get a full range voltage reading from a pressure sensor?

I am making an application using the DIY Force Sensitive Resistor (FSR) taken from this instructable. The resistance of this sensor typycally ranges from 20kOhm when at rest to 9kOhm when pressed. ...
8
votes
2answers
8k views

How do I get an Arduino (5 V) and MPR121 (3.3 V) to talk?

I have the Sparkfun MPR121 I2C Capacitive touch sensor breakout board I have read that it uses 3.3 V, I know that I can't just connect up the 3.3 V power supply output from the Arduino as the ...
7
votes
2answers
6k views

How do I connect a relay and transistor to an Arduino?

Ok, so this is what my relay looks like. I can't figure out what pins I hook the arduino and transistor to, and what pins to hook the the other device. Please help.
3
votes
2answers
3k views

High-side switch 24V 6mA control by Arduino

I would like to ask for best solution for my issue. I need high side switch for 24VDC 6mA (it is enable signal for a device). This device I want to control by Arduino (input 5 V 20mA). What is the ...
8
votes
3answers
3k views

Arduino Bootloader

I am very new to embedded world. I had been till now working only on S/W Can anyone please explain me the use of the Arduino Bootloader? I want Arduino to perform some simple mathematics using some ...
6
votes
2answers
8k views

Driving Solenoids from Arduino

I was wondering what the best way to run a solenoid would be from an Arduino board. I was thinking about using a MOSFET that runs into a relay to turn on the solenoid but am not sure how to go about ...
3
votes
1answer
7k views

Calculationg base-resistor between microcontroller and transistor

I'm curious, when connecting my 2N2222 transistor's base to a PWM output pin on my Arduino, I know the Arduino can deliver a maximum of 40mA current. The 2N2222 only requires around 5 to 10 mA on it's ...
3
votes
1answer
2k views

Arduino Battery Over-Discharge Protection (O-DP)

I am getting an Arduino Uno soon, and am planning to run off a 8-cell NiMH battery pack (through the power jack). Assuming a .9V cut-off per cell, that'll mean a 7.2 cut-off voltage. How would I wire ...
1
vote
2answers
9k views

Arduino, NPN and common cathode RGBs

I'm trying to design a mood light system using 4 RGB LEDs which will be powered by an external 9V source and an Arduino for processing. Link to Fritzing file Part list: 3 x 2n2222 transistors (NPN) ...
6
votes
3answers
9k views

Best way to control 130 - 140 LEDS with Arduino Uno 32/64 bit led drivers?

I am new to electronic prototyping and had a few questions. I need to control 132 LEDs individually. I want to make 3 rows ( 2 rows of 60 and 1 row of 12) I think i can matrix them but i would still ...
7
votes
2answers
8k views

Problems with homemade RS232-to-TTL converter board based on TI's MAX232

I've designed an RS232-to-TTL converter board based on TI's MAX232 IC that I plan to use to program a few custom Arduino boards that I have. However, I'm having trouble with the board and I'm hoping ...
4
votes
3answers
28k views

How to connect 20 wireless sensors in one receiver with arduino?

I live in a house with many doors and windows and I plan - as an easy project - to be able to detect and see which door/window is open using simple leds. What I do not want to do is to have 2 or 3 ...
3
votes
4answers
14k views

How can I drive 12v LEDs from my Arduino Nano?

Background I am building a scale RC helicopter and ordered a bunch of 3mm LEDs to give it some nice navigation and strobe lights which I plan to drive with an Arduino Nano. Problem is that I goofed ...
1
vote
2answers
2k views

15V 3A dc motor PWM frequency setting

What is a suitable frequency for 15V/3A DC motor? Is there any effect on the motor when the frequency is changing? I am confused with this until now and the Internet shows a lot of theory that ...
32
votes
2answers
65k views

Purpose of the diode and capacitor in this motor circuit

I'm hooking up a small DC motor to an arduino using an NPN transistor using the following diagrams I found online: The circuit works, and I'm successfully able to make the motor run. Now, I'm ...
49
votes
17answers
35k views

Complete alternatives to the Arduino IDE? [closed]

I'm not that big of a fan of the official Arduino IDE (in terms of visuals), so I've started looking for nicer alternatives. However, most of the projects I've found are in alpha/beta and are ...
12
votes
8answers
24k views

Wireless communication over long distances

Would like to communicate between an Arduino and a PC but over a distance of 2500+ feet outside in the open, wirelessly. What would be the best way of doing this? The communcation devices I have ...
11
votes
4answers
63k views

How to wire up a 3-wire load cell/strain gauge and an amplifier?

I have a 3-wire load sensor that looks like this: I'm trying to wire it up to my Arduino to detect changes in weight. From what I understand, the changes in voltage are so small that the Arduino can'...
15
votes
5answers
9k views

RTOS for Arduino?

is there any project of an rtos that works on arduino ?
24
votes
7answers
63k views

Arduino Uno R3: Directly supply regulated 5V to 5V pin?

I'd like to use an Arduino Uno R3 battery powered a datalogger. I want do supply it directly with a Step-Up regulated 5V rechargable battery powersource at power ...
11
votes
3answers
34k views

Arduino: better microsecond resolution than micros()?

The micros() documentation notes that the return value will always be a multiple of 4. Is there any way to get a higher resolution microsecond click, preferably down to the 1 microsecond level? ...
15
votes
5answers
32k views

Simple and safe solution to control a power plug with Arduino or PC [closed]

What solutions are available to control a power plug (or even if possible a light socket), i.e. turning it On and Off? I have looked for xbee/zigbee solutions but there doesn't seem to be a solution ...