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1  Using Arduino / Project Guidance / Re: Kickstarter + Arduino + Bluetooth = have to pay license fees for bluetooth? on: August 25, 2014, 06:24:50 pm
Maybe I'm missing something, but if you are buying an HC-05 board, wouldn't the original seller/designer of the board have paid the license fees?  Now, if you are designing your own bluetooth radio from scratch, then obviously you need to pay the IP costs for licensing bluetooth.
2  Using Arduino / Project Guidance / Re: self-controlled power switch on: August 20, 2014, 11:35:47 am
You might want to ask this over at, which is Paul Stoffregen's (designer of the Teensy) forum, where he is more likely to notice it.
3  Using Arduino / Project Guidance / Re: Is my Digital PWM Pin D9 burned? on: August 09, 2014, 03:49:02 pm
Note, if you use the servo library on the Uno, you cannot use PWM on pins 9 and 10, since the servo library uses the timer for pin 9/10 PWM for its own uses.  There may be other libraries that use the same timer:

The way to test it out, is put a normal led + resistor on pin 9, and run a sketch that only does analogWrite to pin 9 using different values, and see whether the led dims or not.
4  Using Arduino / Microcontrollers / Re: arm with ce / vga 5v ? on: August 06, 2014, 09:38:09 pm
If you are only building a few units, plunking down the $3 for a level converter might be a lot simpler.  You do have problems for high speed protocols, whether the level converter is fast enough.
5  Using Arduino / Networking, Protocols, and Devices / Re: Arduino doesnt work with 3 serials.. on: August 06, 2014, 07:07:39 pm
According to the documentation, the SoftwareSerial library can only support one serial port that is reading at a time.

You probably should go to a micrprocessor that has at least three hardware serial ports, such as the Mega 2560, the Due, the DigiX all have support for 4 hardware serial ports, and the Teensy 3.0/3.1 has support for 3 hardware serial ports.  To use the hardware serial ports, you use Serial0/Serial1/Serial2/Serial3 on the Mega/Due/DigiX, and Serial1/Serial2/Serial3 on the Teensy 3.x.  Note, in these machines pins 0/1 are not connected to the USB, and you continue to use Serial to write to the USB connection.
6  Using Arduino / Microcontrollers / Re: arm with ce / vga 5v ? on: August 06, 2014, 03:21:26 pm
Only ARM chip I have ever seen with 5v tolerant inputs is the LPC1114 which is a microcontroller and certainly not linux capable.
The Teensy 3.1 which uses the Freescale Cortex-M4, MK20DX256VLH7 has 5v tolerant inputs for digital pins.  The analog pins that also support digital input/output, will take 5v inputs, but anything above 3.3v will return 1,023.  The analog pins A10-A14, which cannot be used for digital input/output are not 5v tolerant.  Note, the Teensy 3.1 is also a microprocessor (and uses modified Arduino libraries), and will not run Linux.

It might be simpler to include a 5v Arduino class machine with a small form factor (pro mini, nano, etc.) to do the 5v work, and then communicate with the Linux system via i2c (you will need a level converter for i2c).  This assumes you only read your sensors i2c time scales (100kHz).
7  Using Arduino / Project Guidance / Re: Portable project with LED matrix - power requirements on: August 06, 2014, 09:08:14 am sells switched step-up voltage regulators that can handle the current, but whether your li-po's can  3-4 amps of power when you need it, I don't know.  This is a step-up regulator that takes in voltage at least 2.9v and less than 5v, and produces 5v of power and up to 5 amps:  According to the graphs, 3.3v input tops out at 2 amps with 75% efficiency.

Note, you will generally need to worry about both the battery and the voltage regulator heating up.  To quote from the product page: During normal operation, this product can get hot enough to burn you. Take care when handling this product or other components connected to it.

If you aren't sure what power source you will be using, or you want the flexibility to use li-po's, AA batteries, and 9v batteries, also sells step-up/step-down converters.  These aren't as efficient as a step-up or step-down converter.  This regulator takes power from 3v to 30v, and produces up to 2 amps:  However, according to the power graphs, you can only get about 1.4 amps from 3.7v.

I've bought some Pololu regulators, but so far, I haven't actually used them for serious use.  I do use other pololu products and I'm satisified with them.

Also, Adafruit's new PowerBoost 1000 is generally rated for 1a, but in the text, they say they've gotten 2a from Li-po batteries:  I bought their previous PowerBoost 500, but either I got a dead unit, or I messed it up via mis-soldering (unfortunately, all too likely for me), and I wasn't able to get it to work.
8  Using Arduino / Project Guidance / Re: Help with Leonardo on: August 04, 2014, 09:54:09 am
9  Using Arduino / Project Guidance / Re: Is it feasible to use a sound detector to activate a camera? on: August 04, 2014, 08:15:23 am
The camera uses an RM-1 remote control, which is an infrared device.  Note, in my experience, there is some delay in using IR devices between the time the button is pressed, and when the camera finally gets around to taking the picture.  It depends on what you are taking pictures of, whether this is a problem.

There is at least one library for controlling cameras with IR controls:

If you don't mind opening up the camera, an alternative way is to add wires to the push button.  Obviously, if you do this, you will void a warranty, but in your case, there is no warranty as Olympus warranties generally are for 1 year and only for the original owner (in Europe, Olympus is required to give a second warranty that is transferable, and is longer than the 1 year warranty it offers elsewhere).  Just to be cautious, I would put an opto-coupler between the Arduino and the shutter button, so that the camera is not electrically in the circuit with the Arduino (opto-coupler have a LED and light sensor inside the chip, and power on one side turns on the LED, and the light sensor completes the circuit for the other side):

As people have mentioned, you can use a servo to press the button.  In this video on making a pole mounted camera, it discusses putting in a servo at about 1 minute, 50 seconds into the video:

The Stylus 500 is almost 10 years old (introduced November 29, 2004).  Hopefully it is still functioning well for you.  I would worry whether batteries still could hold a charge.  Compared to other manufacturers, Olympus has a fairly good record of using the same battery for multiple generations, so there was less chance of being stranded because the battery no longer is available.  It looks like this battery is still used in current cameras (Olympus TG-850), and you can pick up clone batteries readily.  FWIW, I tend to use wasabi clone batteries that sells (  I do have problems with the 3rd party chargers, as they are somewhat fiddily in terms of seating the battery so it charges.

Unfortunately, it uses xD memory cards (common to Olympus cameras of the time).  I don't believe the xD memory cards are still being manufactured, but hopefully you can still get them in the used marketplace.  If memory, serves there were 3 generations of xD memory cards, and early cameras could not use the 2GB cards.  I have gotten rid of my cameras that took xD cards, so I no longer worry about xD.
10  Using Arduino / Project Guidance / Re: Help with Leonardo on: August 04, 2014, 07:57:42 am
As far as I can see the two extra pins marked SCL and SDA are directly connected to pins D2 and D3.
Yes.  The SCL/SDA pins are meant to be a common place to put the i2c pins.  On the Uno, the i2c pins are on A4/A5, on the Leonardo, the i2c pins are 2/3, on the Mega the i2c pins are 20/21.

In terms of the led pin (pin 13 in the case of the Leonardo), you can use it for an output pin (the builtin led will also flash at the same time), but if you use it for input, you have to compensate for the resistor that is part of the led circuitry.  Pin 13 on the Leonardo is capable of doing PWM.
11  Using Arduino / Programming Questions / Re: Conditional using a float that is "-0" and how that works on: August 03, 2014, 09:40:52 am
With computers and floating point, there is no such thing as "exactly as they are".

The number 0.1 can't be represented exactly as a binary floating point number, just for example.

For binary floating point, yes.

However, to put on my nerd compiler hat, some computers have decimal floating point as well as binary floating point.  Under decimal floating point, the digits are in decimal not in binary, so 1.2 has an exact representation.  IBM power6/power7/power8 servers do have hardware support for decimal floating point (using the _Decimal32, _Decimal64, and _Decimal128 types).  Intel/AMD x86 platforms using the GCC compiler have had software emulation of decimal floating point for several years now.  Neither of these platforms are commonly used in microprocessors like the Arduino, so for this audience, it isn't an option.

If you program in COBOL or PL/1, those languages had decimal floating point types as well and the compiler would have to simulate the decimal arithmetic if the machine did not provide hardware support for decimal arithmetic.  Similarly, I worked on a language (DG/L) 30 years ago that is now dead, that allowed you to add strings, and it would do it in decimal.

But the point is it isn't always true that floating point does not have an exact decimal representation.
12  Using Arduino / Programming Questions / Re: Conditional using a float that is "-0" and how that works on: August 01, 2014, 06:46:14 am
-0.0 is special in IEEE 754 arithmetic.  The software (or hardware in bigger machines) will treat -0.0 as +0.0 in comparison.  If you do (-0.0) + (-0.0) you will get +0.0.  Under IEEE rules, the only ways to test if something is -0.0 is to use the signbit or copysign/copysignf functions.

#include <math.h>

// ...

bool is_neg_zero1 (float f)
  return (f == 0.0f) && signbit (f);

bool is_neg_zero2 (float f)
  return (f == 0.0f) && copysignf (1.0f, f) == -1.0f;
13  Using Arduino / Installation & Troubleshooting / Re: Mounting hardware for Arduino boards on: July 31, 2014, 06:29:29 pm
You might move from an Uno to something that can be soldered to a perf-board.  Most perf-boards have standard sized mounting holes at regular places.  I tend to like the Adafruit perma-proto boards.  For example, here is a combo pack of the 3 main sizes:, plus there are 2 other perma-proto boards that fit inside the small and standard sized Altoids mint tins.

In terms of chips, you can buy various chips made for proto-boards.  I just picked up a Pololu A-Star 32U4 LV (  The A-Star series was just announced at pololu, and it uses an ATmega32u4, which is the same chip that is in the Leonardo (Uno uses ATmega328p).  There was a sale that expires today (July 31st) that had them for 1/2 off (code ASTAR50 if you act quickly).  I went for this because it had a built-in step-up/step-down voltage regulator, USB serial support, and the i2c pins are on the outside.  If you don't need those things, you can get Arduino Pro Mini clone boards fairly cheaply.

If you want to buy an official licensed board, the Arduino shop has the Micro for sale (the Micro has the ATmega32u4 in it, unfortunately the Arduino store is sold out of the ATmega328p boards that aren't development kits like the UNO):
14  General Category / General Discussion / Re: NavSpark: 32-bit Arduino-style device with built-in GPS for $19 on: July 30, 2014, 06:52:41 am
You might get a more detailed answer on pluses and perhaps minuses from users at the navspark site, which has a forum:  From the specs, the navspark has one hardware uart that can do read/write, and another than only do write, so you could hook up the modem for the read/write port, and hook up a display either to the write only uart, or via spi (it doesn't list i2c).

Note, the indegogo campaign that was mentioned at the start of this thread is no longer active, but it was successful in raising money, and the company now sell the navspark's from their store.
15  Using Arduino / General Electronics / Re: Arduino Header Cables 2F to 1F on: July 29, 2014, 05:30:27 pm
I suspect most of us just slice wire in the middle, and connect what we need, using solder to make a permanent connection, and putting heat shrink material around the joint and shrink it like zaxarias's post.

But if you are still a solder newbie, you can get cold splice wire taps that allow you to connect cables without soldering (you do need to use enough force to do the splice with large pliers).  Adafruit sells these:, but you probably can find similar things elsewhere.  Note, you want to buy splices for the size of wire you are using.  The Adafruit version can do 22-26 gauge wire, which typically matches what most people use.

Alternatively, if it is power or ground wires, you can use standard breadboards, and they have red/black columns that allow you to plug in separate wires to the board.  Even if they aren't power/ground wires, you can plug up to 5 wires into a row on the breadboard, and they are are connected.  You do have to make sure sure if you are driving signals through the wires, that the total current is less than or equal to the amount the microprocessor can send through a given signal pin.  Here is a tutorial on breadboards:

If you want to start making your own wire that are custom sized, you can get crimp connectors that you can attach to stranded wire.  I've used the connectors from  I find crimping the female end on a little challenging with just needle nose pliers, and one of these days I need to get a proper crimping tool.
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