Powering up Arduino BT using wall warts

Have just receive Arduino BT. There is a + and - terminal on it. And I would like to power it straight from the wall using a hand phone charger. The writing on charger is:

Input : 230v~ 50Hz 0.1A Output: 3.6V (DC Symbol) 600mA

It is within the voltage spec from http://arduino.cc/en/Main/ArduinoBoardBluetooth which is 1.2v to 5.5v.

  1. Howabout the Amperage?

  2. Can I use multimeter to find which is + and - terminal in the power supply and then connect ps + to Arduino BT + terminal. And connect ps - to Arduino BT - terminal.


OK... I have done the multimeter check on each of the charger/wallwart terminal and it is reading 6.12V.

Was expecting it to be 3.6v is at some load. So ok, it does not have that 3.6v as per this article http://www.horrorseek.com/home/halloween/wolfstone/Power/powwal_WallWarts.html#WallWartsPutOutWrongVoltage

Can I still use it?

Or perhaps use LM785 and then use the 5V out of LM785.

Perhaps this kind of question is too noob. Or maybe everyone is still sleeping!

The Arduino BT is a 5V device. The 6.12V that you measured is the no-load voltage for an unregulated power supply. As soon as any significant load is applied, that voltage will drop to 3.6V, which will be too low to power the Arduino.

You’d be better off with the proper wall wart - anything that delivers a loaded voltage of 7.2 or more is good.

Hi AC24V directly from the image below using the 12v motor. What is helpful?

Hi You are not a good look at the image. Look down on others is not right to say. The following image (the connector near the top) to enter the silicon bridge, which connects to safely connect to the power and intelligence to the reverse polarity diode. AC adapter with sw they rectifier with center tap 12v rectifier can be switched 24V doubling. Test board (the back of the picture below) is not listed in the type of power switch 4 sw. The last one can extract a low voltage to high voltage. Not to forget, but from a lack of power, can not produce even greater power.

Hi You just put the power connector on the silicon bridge, do you notice the problem can be avoided saying that the DC power supply polarity?

PaulS The Arduino BT is a 5V device. The 6.12V that you measured is the no-load voltage for an unregulated power supply. As soon as any significant load is applied, that voltage will drop to 3.6V, which will be too low to power the Arduino.

According to the Arduino BT page the voltage range is from 1.2v to 5.5v.

So 3.6V is within that range right? Unless the information on Arduino.cc Hardware page is outdated.

Anyway, would love to know how everyone else is doing this (yup! I have done nothing with the Arduino BT for the past month! :'( Sweat very much thinking about possibility of seeing smoke on this very expensive piece of hardware).

Have seen it being powered up with 2 AA battery. So probably I should try this first.

Thanks for all the reply! Though I have to agree that Apollo21 post really does not make sense at all.

Just adding that I am thinking about taking 5V out from another Arduino (Uno or Duemilanove) to power up the Arduino BT.

I think this should work!

A big hmmm ... after going through 2 set of AA batteries (now on the battery 5th and 6th).

I think the board powered up correctly. But having problem with uploading program. I don't see the normal LED blinking when programming. and then got the same error as this guy.


Binary sketch size: 1010 bytes (of a 28672 byte maximum) avrdude: stk500_getsync(): not in sync: resp=0x00 avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

Tried the guy solution but my windows 7 64 bit using cmd shell with administrator priviledge says cannot find COM18.

The com port is correct because I have check it multiple time. My suspicion is low power and communication error. But this is just assumption because really have no idea what is resp 0x14 and 0x51.

I know one other person who is having the same problem. Not sure the guy is using battery of power from the wall.

I am glad that I use battery because otherwise will think that fried the board etc. But since I'm not, and take precaution with diode to rule out reverse polarity, higher probability that the board is not fried. But some other problem.

At this point either I take 5v from another arduino board or use a wall wart. So my question to PaulS is still in need of answer (3 post up).

Best Regards!

UPDATE: After lots of dead batteries. Decide to change to rechargeable 1.2v batteries with 4 battery instead of 2. This time around the voltage measured on battery terminal should be 4.8v. But I am seeing 5.4 volt just after charge. Diode voltage drop bring this value to around 4.9v.

Much better in term of Arduino BT not disconnected at the same time when low battery LED is on. But again, it shows same error :'( . From avrdude command prompt

avrdude: Version 5.4-arduino, compiled on Oct 11 2007 at 19:12:32 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/

System wide configuration file is "D:\app\arduino-0021\hardware\tools\a vr\etc\avrdude.conf"

Using Port : COM3 Using Programmer : stk500v1 Overriding Baud Rate : 9600 avrdude: ser_open(): setting dtr avrdude: Send: 0 [30] [20] avrdude: Send: 0 [30] [20] avrdude: Send: 0 [30] [20] avrdude: Recv: avrdude: stk500_getsync(): not in sync: resp=0x00 avrdude: Send: Q [51] [20] avrdude: Recv: avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

avrdude done. Thank you.

avrdude does not run at all before the battery change. So I take this as an improvement power wise. But getting same error with avrdude say something else.

Discovered several more forum post with same problem

http://forums.adafruit.com/viewtopic.php?f=25&t=6511 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1204809767 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1290070638

Begin thinking about the built in LED is not connected to digital I/0 pin 13. Because there is 1 LED that is constantly on which is the power LED. And there is another LED that is labelled as BATT LOW that is only on when battery is about to die.

I am assuming that the battery low LED is the LED that blinks when Arduino board start or during programming of the board. But so far have not seen that happen.

Just bouncing back some idea.

To continue this monologue. (Perhaps this is the bane of living on the other side of the world, I am practically troubleshooting by myself while other people is partying, sleeping or having breakfast and starting their day). And finish with a good conclusion. Because finally after 1 day plus (or 22 days depending on how to look at it!) manage to get it working.

So let's have all the glory (and frustration) in point form.

==1== This thread begin as I ask the question of how to power Arduino BT. The original idea is to use a wall wart with rated output of 3.6V under load. However upon checking the voltage using multimeter, found that it is 6.2V instead. PaulS later point out that if connected to Arduino board with proper load. The operating voltage should be 3.6V.

==2== Decide not to take the risk (in other words chicken out). So Instead of using the wall wart, use 2AA batteries. Multimeter show around 2.8V to 3.2V. Unfortunately I use crappy battery. The fact is that even though it power up, can't program the board. Failure to program is not because of the battery or the low charge hold by the batteries. But, since the battery run out very so often it give wrong perception about the problem. Beside this, the troubleshooting process is interupted by changing batteries, pairing the device again and restart troubleshooting. This is improved by using 4x AA batteries with each 1.2V and 2100mAH. In total I get 4.8V to just bellow 5.5V due to diode voltage drop. It is still a mystery to me why 4 x 1.2V give more than 5V.

WARNING : Do not use 4 x 1.5V in series. This will result to 6V which exceed Arduino BT max voltage at 5.5V

==3== This is the most important point. The reason fail to program Arduino BT. My theory is that the Bluetooth chip (Blue Giga) is hogging Arduino serial communication. Which also use to program the onboard ATMEGA328 chip. This theory is formed by reading bellow thread


Several quote

Reply1 - Adilson Akashi I don´t know if this problem is the same, but I read somewhere in this forum about a sketch that sends constantly messages from arduino´s serial port, and makes it uncommunicable to receive new sketches. Is the actual sketch a loop of this kind?

Reply11 -pwillard That's why there is supposed to be a short delay after pressing reset... no? That delay allows you to UPLOAD a new sketch with the bootloader. If you wait too long... you miss the window and you will have a serial conflict as seen.

If you have a different bootloader that has the delay removed... oh well.

Reply13 - halley Connect the board to the computer. Ensure you've selected the right serial port in the IDE. Hit the Reset button on the board. Hit the Upload Sketch button on the IDE before two seconds has elapsed.

When you hit the reset button, the board starts running the bootloader program instead of your program. The bootloader program watches the serial connection for two seconds, and if there's nothing that looks like a valid program-upload process being attempted, it will start running your program.

In essence pressing the reset button before immediately click the upload button solved the failure to program issue. There is 5 second window before the Blue Giga chip start to hog the serial com. At least this is what I think!

==4== But that is not it. There is a plot twist in this story. After successfully uploading Blink sample, still there is no bloody blinking LED. As noted in my earlier post. Even though the hardware page described Arduino BT as having built in LED. It miss that one LED connected to Digital I/O pin 13. Running the Blink sample on Uno or Duemilanove will result to immediate and visible result. But this does not apply to Arduino BT. Need to connect LED to pin 13 to see the result on Arduino BT. So after doing the necessary, finally there is blinky!

It is good to ponder. Why this issue is not highlighted in the Arduino BT hardware page? So many forum post where people are describing this same issue with Arduino BT and asking for help.

Best Regards & Happy Weekends