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1  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 10:29:04 am
Sounds like a nice add-on, the battery thing. But is soldering required? Also, note that it's a Teensy 3.0 rather than 3.1. I didn't need the extra power, I only chose it because of its size. Is there a version for 3.0?
The 3.0 and 3.1 Teensy's have the same pinout for the power pins, so you can use either.  The reset pin of the Teensy 3.0 (in the back row of pins) became A14/DAC (analog output) in the Teensy 3.1, and a new pad was added for the reset capability underneath the teensy.

I just got mine, but I haven't hooked it up yet (I have several Teensy 3.0's and one 3.1).

You would need basic soldering to at least bring out the pins so you can use it on a breadboard.  While it is meant to be soldered underneath the Teensy, you don't have to do that if you would prefer some other setup.
2  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 09:21:47 am
Note, the Teensy can be powered by either applying 3.3v to one of the 3.3v pins (one on the side, one on the back), or by applying 3.7 to 5.5 volts to the VIN pin.  By default VIN and VUSB are connected, so you can hook up anything that provides 5 volts of power via a micro-B USB plug.  If you want to separate using USB from power control, you can cut the solder jumper on the back of the Teensy, and then you need to feed power to the 3.3v or VIN pins with appropriate voltage.

For the li-po/li-poly batteries that nominally produce 3.7v (4.2v when freshly charged), you can just hook them directly to the VIN and ground pins of the Teensy.  You may need to think about low voltage protection, if the battery you are using does not have low power cutoff.

You could use this device to hook a li-po/li-poly to the Teensy:

There are quite a few ways to provide regulated 5v power.  Pololu sells several different voltage regulators, depending on whether you are coming from a lower voltage, a higher voltage, or a voltage that ranges from low to high and also how many amps you need to draw from the battery:

Adafruit also sells its powerboost regulators:  It also sells its previous Minty boost:
3  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 01:34:18 am
If your second arduino/teensy is going to be connected via a wire to the first, you might think about powering the sensor microprocessor via that wire, instead of having to deal with a battery solution.  The project chaindunio that just ran a successful kickstarter campaign, is one way to do it with rs485 connections and power over a cat6 cable (rs485 is a lot better when communicating over a distance than things like i2c or virtualwire).  Now, you likely won't be able to buy a chaindunio until December, but perhaps you can use them for ideas of how to do it:
4  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 12:38:50 am
With a motion sensor, it pretty much has to be on all of the time, so the processor can't go into deep sleep mode until an interrupt occurs.  However, you don't need to run the processor at full speed, so you can save battery time by running the processor slower than the normal speed.  There you might need something more powerful if you need to run for days or weeks between recharging batteries (deep cycle marine batteries for instance).

Adafruit does sell solar chargers that keep lipo batteries topped off, and it might be enough to keep the unit going for a lot longer if there are sunny days.

Good luck.
5  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 12:34:10 am
I've used that very battery pack for projects needing 5 volts.
It is a great option for this.
It handles it's own charging so you don't have to deal with it.

Assuming you meant the battery from ebay with 2 18650 batteries, yeah, it is a nice battery.  I need sometime to do a test to see how long it runs driving neopixel rings or some such.
6  Using Arduino / Project Guidance / Re: Battery Pack reccomendations? on: September 06, 2014, 12:06:55 am
Note, get your thing working first without batteries, before trying to deal with batteries.

I tend to think you don't want to feed 12v to an Arduino, as the Arduino will like just waste the extra power, converting it into heat.  The simplest thing is to get 5v battery packs with a USB plug, and use that to power either the Arduino or Teensy as they both run off of USB power.  Typically these batteries are meant to recharge cell phones.  I bought a 5000maH EZOPower battery that has run the Uno doing blink for about 4 days:

Radio Shack sells a bunch of these phone charger batteries:

Unfortunately, they stopped selling my favorite enercell battery that had a built-in plug, 2 USB outlets, and a variable power outlet that would allow me to power something with 3, 4.5, 5, 6, 7.5, 9, or 12 volts which was handy when dealing with devices with particular requirements.  I picked up two of these when they had them on sale.

I also bought this battery from ebay, which is smaller and has less total power and it only gives 9v/12v.  I bought the 18650 batteries separately from a US supplier:

Because this battery takes more 18650 cells, it might provide power for a longer period of time than the above unit:

Some of the newer phone charger batteries will turn themselves off if the processor doesn't use enough energy.  If you have one of these, you might be able to program the Arduino/Teensy so every so often it uses a burst of energy to keep going.  I don't have a battery like this, so I haven't done anything about it so far.   In particular, the 9v battery meant for smoke detectors is meant for devices that use very little juice, but need to run for a year or so.  If you use them for an Arduino, they will drain fairly quickly.

Now, you didn't mention what kind of power you need for the other parts of your project.  If it involves servos, they typically want higher power, and you need to think about powering them.

In general, you want to stay away from non-rechargeable batteries, as the cost will mount up as you use them.  Instead, but a decent charger (if it is AA batteries, you want a charger that charges individual cells, and not doing pairs at a time).

Li-on/Li-poly batteries are popular, particularly for 3.3v processors.  Adafruit sells various sized li-on batteries and chargers (other places do also, I'm more familiar with Adafruit's products).  They also sell a shield that takes a li-on battery and boosts the voltage up to 5v for the Uno.  One note, be careful of the wires, as it is easy to pull them out of the battery, and you will need to resolder the wire to the battery:

If you are going to be using batteries for a long period of time, you will need to spend some time making the processor as efficient as possible (after you get it working in the first place).  Most of my interests are in stuff that is part of costumes, and there I just make sure my batteries can last a day, and then I recharge them at night.  Nick Gammon wrote a nice tutorial on running Arduino programs as long as possible on batteries:

Over at the Teensy forums, they talk about low power issues from time to time (also the latest teensydunio has options to run Teensy's at lower clock voltages).  You might want to read the various discussions on it:
7  Using Arduino / Project Guidance / Re: Camera self-timer on: September 05, 2014, 10:18:23 am
Ah well, there you go. Trust Polaroid to do it differently............
The SX-70 predates the modern cameras that take electronic shutter releases, and I believe the original versions did not have automatic focusing, so it didn't need the 3rd contact to do the 1/2 press action to get the camera to auto focus (evidently later versions had sonar autofocusing).  Of course given that there are something 10-20 different cables for shutter releases, with several manufacturers having different cables for different models, I think it is unfair to say they did things differently.  In the area of shutter releases, there is a lot of variety.
8  Using Arduino / Project Guidance / Re: Camera self-timer on: September 04, 2014, 10:00:53 am
You probably want to use an opto-coupler instead of a relay
I thought of that also, but most circuits require a voltage across the photo sensor?
Maybe not? if not then that's an option.

In most/all of the electronic shutter releases, the shutter release merely connects the ground to the focus and fire wires, and the camera provides the voltage via its battery.  There is no separate battery in the simple wired shutter releases (in the wireless and timer shutter releases you need a battery to do the extra stuff).  You can verify this by connecting the wires directly to see that it fires.

Some cameras need the focus/ground connection to be on before the fire/ground connection fires the camera, some the focus and fire are completely separate, and you can connect the fire/ground wires to fire the camera without connecting the focus/ground.

In the 3.5mm/2.5mm cables for shutter releases I have used, the band next to the sleeve is the common ground, the middle band is for doing the 1/2 press of the shutter action (focus), and the outer band is for firing the camera.  If you don't care about the distinction between focus and fire, you can wire them together.  Some of my older cameras need a longer period to focus when the camera is in live view mode, so I do need to have separate controls.

Since the camera is normally powered via a battery, the camera's ground is independent of the Arduino, so you probably would not want to use a transistor.

If your camera does not support a wired shutter release, you have several options:
  • It might support an infra-red shutter release, and there are programs to allow the Arduino to act as an IR shutter release;
  • If you are willing to open the camera and void any warranty, you can add additional wires to where the shutter button connects;
  • You can use a servo to press the shutter release.

Some of my Olympus cameras support a wired shutter release, but will not use the shutter release to start/stop movies.  Instead to take movies you need to press a separate button, and if you wanted to do that, you would need to rig up a servo to press the button.
9  Using Arduino / Project Guidance / Re: Camera self-timer on: September 04, 2014, 08:19:13 am
You probably want to use an opto-coupler instead of a relay.  Most relays are bigger and meant to switch more current, and the mechanical relays also tend to make a sound as the relay is switched open/closed.  An opto-coupler is an enclosed chip that has a tiny LED in it, and a tiny photo sensor.  From the Arduino you activate the LED, and when it is activated, the photo sensor completes the circuit.  Here is one such wiring setup that I found via google:

I tend to like the CNY-74 opto-coupler since it provides two independent circuits, and it works well with both 3.3v processors like my Teensy 3.x and 5v processors like my Uno.  On my Olympus cameras, you can control the 1/2 press of the shutter with one circuit, and the full shutter release with the second and first combined.  I use it with my steampunk camera setup where pressing the telegraph key starts the focus action (1/2 press of the shutter) and when you release the telegraph key, it then tells the camera to take the picture.  Here is a US based ebay seller of the CNY-74:

This page describes the pin out for various shutter releases:  In general, if your camera does not take a standard audio 2.5mm/3.5mm connector, you would either buy a cheap remote release for your camera and hack up the wires, or you buy an appropriate cable for shutter releases that use 2.5mm/3.5mm audio jacks to support multiple cameras.

This store for instance sells cables that connect to the pixel shutter release/remote flash setup:
10  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.
11  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.
12  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.
13  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.
14  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.
15  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).
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