15 votes
Accepted

very lightweight low power microcontroller with memory?

I made up a small torch locator which used an ATtiny85 powered from a button-cell (CR2032). It looks like this: Other side: That currently weighs 5.9g. The battery-holder weighs 1.6g so you could ...
  • 36k
12 votes

Arduino Pro Mini is burned by 12v. Can I save it?

1. Your microcontroller is probably/maybe fine; your tiny little voltage regulator is dead; here's why: Sergio, yes, you can probably/perhaps save it: your Arduino (the microcontroller--ie: processor ...
11 votes

Pin 13 fires relay when powering on... How to disable?

There are three things you can do: Remove the bootloader entirely and program the board with a hardware programmer (USB-ASP, Another Arduino, etc). Edit the bootloader source, recompile, and ...
  • 104k
9 votes
Accepted

Arduino 16 MHz with only 3.3V?

Officially, no. Practically, often but not always. If I follow the datasheet to the the letter, this configuration should not work. BUT... After some test, it did work. The data sheet does not ...
8 votes

very lightweight low power microcontroller with memory?

I would personnaly suggest an ATtiny 45/85. It is pretty much a small AVR with 5 GPIOs. You can program it with the Arduino IDE and use the Arduino as ISP. If you can design you own custom PCB, a SMD ...
  • 2,883
7 votes

Wire.endTransmission() Hangs

The device ID and every other stuff is working fine. The only issue being that my code gets stuck at Wire.endTransmission(). Nothing is transmitted until you call Wire.endTransmission() so that is ...
  • 36k
7 votes

IR Receiver interrupt and arduino sleep mode

This is what I have managed to achieve ... Library IRLib - GitHub Version 1.51 March 2015 Copyright 2013-2015 by Chris Young http://tech.cyborg5.com/irlib/ This library is a major rewrite ...
  • 36k
7 votes
Accepted

Problem programming Mini Pro via Arduino as ISP

After poking around for a bit more, it turns out my problem was the baud rate. I could make it work by setting it to 19200, just a little slower. Alternatively, you can modify the ArduinoISP sketch ...
7 votes

Why does this Arduino Pro Mini use a capacitor on the DTR reset line?

Most USB to serial chips set the DTR to LOW on connecting, but it keeps it LOW. This would reset the arduino, but since the DTR never goes HIGH the Arduino will never get out of this reset state, ...
  • 11.2k
6 votes

Getting "avrdude:stk500_recv(): programmer is not responding" while uploading sketch to Arduino Pro Mini

rx -> tx tx -> rx Please check your connections.
  • 61
6 votes
Accepted

Powering an Arduino Pro Mini directly from a LiPo

The only thing about the 3.3V Pro Mini that is actually 3.3V is the 3.3V regulator. The main chip (pretty much the only other component) is good for anything from 1.8V up to 5.5V. Running direct ...
  • 104k
6 votes
Accepted

Powering from 3V coin cell to VCC, using I/O pin as supply GND

Can I use a I/O as (input/supply) GND? You can use an I/O pin as a supply for another (low power) device, but you should power the Arduino itself from its Vcc and GND pins. I could use the reset ...
  • 39.7k
6 votes
Accepted

How to power my Arduino mini using wall socket?

I have connected the Relay and IR receiver directly to the Arduino mini. Pin 10-14 are used for the relays Ins and PWD 3 for IR output. I hope you don't mean that you have connected the coils of ...
  • 2,103
6 votes
Accepted

Measuring li-ion that arduino is running from

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....
  • 39.7k
6 votes
Accepted

Pro Mini - Using RAW pin for 3.3v input

It is not ideal, no. The RAW pin first goes into a 3.3V voltage regulator whose dropout voltage is up to 200mV (worst case). That means that you would get around 3.1V out, and it wouldn't be ...
  • 104k
5 votes

Audio Frequency White Noise generation using Arduino Mini Pro

Mike's answer uses a Fibonacci Linear Feedback Shift Register configuration, but the compactness Galois Linear Feedback Shift Register Configuration could be faster: #define speakerPin 8 unsigned ...
  • 2,322
5 votes

High Frequency Sine Wave Generation

To generate a square wave, you only need to update the output at a rate of two points per cycle. (Technically, when the Arduino's PWM output is configured for 50% duty cycle, that's a square wave at ...
  • 450
5 votes

Most compact method of powering Arduino from wall socket

I use this one, 5V, 3W, very small, and only $3 on Aliexpress. http://www.hlktech.net/product_detail.php?ProId=54
  • 51
5 votes
Accepted

Having difficulty uploading sketch to an Arduino Pro Mini

You need to hook it up with the Arduino TX --> FTDI RX, and vise versa, so crossed over. If you take the FTDI and hook it up to the Ardiono pin to pin as you have it pictured it should work, provided ...
  • 393
5 votes

Mounting Arduino in an enclosure

What type of box? Howmany times/how easily do you want to remove the Arduino Mini? Hot glue Hot glue is the way to go in many occasions. It does not conduct electricity, so is pretty safe. (Please ...
  • 2,703
5 votes
Accepted

Arduino PRO Mini - The pads [was "jumpers"] on the back and Low Power Consumption

Both responses are correct but be mindful that this is a SparkFun feature. An Arduino Pro Mini from China won't necessarily have the SJ1 pad. 1) Like Gerben said, the pads on the underside of the ...
  • 66
5 votes

Arduino 16 MHz with only 3.3V?

According to the datasheet you need 3.78V to run at 16 MHz, and 3.3V isn't that far off. I would be surprised, for example, if it stopped working at 3.77V, because that would mean that the operating ...
  • 36k
4 votes

Most compact method of powering Arduino from wall socket

wanted to do a similar thing and I found and just ordered these: http://uk.farnell.com/recom-power/rac03-05scr-277/conv-ac-dc-3w-90-305v-in-5v-out/dp/2289701 A fully sealed power supply, disk-shaped,...
  • 487
4 votes

Most compact method of powering Arduino from wall socket

An obvious answer has been omitted which is: transformerless power supply. If your average power requirements are low (<10mA) then this is the most compact way to achieve the desired voltage. For ...
  • 141
4 votes

Most compact method of powering Arduino from wall socket

Try an LED driver. Their typical output is 11.8V DC, which is in perfect specs for the Arduino. You can find them nowadays in all shapes and sizes, round or square, low profile or boxy. A 500ma ...
  • 41
4 votes
Accepted

Unable to power an Arduino Pro Mini through the RAW pin

I am not completely familiar with that specific board, but according to the schematic there is a solder jumper which is used to isolate the RAW voltage regulator from the rest of the system "for low ...
  • 104k
4 votes
Accepted

Soldering Arduino Pro Mini's disaligned pins

That's indeed quite an problem. If you don't mind losing 2 analog pin, you could solder some jumper-wires between A4 and A2; and between A5 and A3. Then you could connect your I2C lines to pins A2 ...
  • 11.2k
4 votes

Arduino 16 MHz with only 3.3V?

A little test, not very scientific, but shows it runs fine on 3.3V - https://www.youtube.com/watch?v=If0eOa0Uj5I. Again, if you would like to stay withing the specification just use a "clock divider/...
  • 579
4 votes
Accepted

Substitute for FTDI board?

All prices in USD w/ free shipping. FT232RL breakout board: Aliexpress: $1.55 eBay: $1.81 They are probably counterfeit. A Windows driver update (AKA "FTDIgate") at one point "bricked" them but I'm ...
  • 3,933
4 votes
Accepted

Auto Reset during programming Arduino

A Reset is necessary to activate the Bootloader and allow programming. Without the DTR signal the Reset button has to be pressed just before starting the upload from the Arduino IDE.
  • 7,929

Only top scored, non community-wiki answers of a minimum length are eligible