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Thread: New on Teensy, products choice and the logic.

  1. #1
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    New on Teensy, products choice and the logic.

    Hi. Umm well after some trainings on arduino i developed my ideas and felt the need of Speed and i saw that its not only the hardware side does the work but libraries also. When i was researching to choose a Teensy i saw a video in internet and its said that taking 750 fps with and arduino is light years away and in video a Teensy was doing it properly.
    So i decided to get Teensy 3.6 . Now i have some questions and i would like to give u a little warning because here is a newbee who tries to understand all these articles and technical explainings which is Not in my mother language. So i wld request u to be soft to me .haha. ok here is the dealS;

    Its all started when i was trying to learn to use multiple strands in my project and first i have seen the system which is named as Parallel Output. And then i saw a specific library written for this which is named as OctoWS2811.

    1) its said only teensy 3.0 and 3.1 is compitable.. but i think thats about DMA channels. And teensy 3.6 has bunch of them and also i saw teensy 3.6 is used in picture demonstration of the octaws2811 adaptor so i guess teensy 3.6 is capable for octaws2811 library. Am i right?

    2) And i want to ask if teensy hardware is compitable with libraries that i use with arduino. I use fastled library and maybe softwareserial... but do i have anything to concern about Compitability or anything i shld know ? Because i dont want to choose a wrong product..

    3) i see that there is a special adaptor to use with octaws2811 library. Thats so nice.. what i think is this adaptor includes a level shifter and some resistors for better singals through the Cat6 cable.. so if i get teensy 3.6 and this adaptor and its all ok? Because teensy 3.6 has no 5V tolerant. But 3.5 has! So i am i right about teensy 3.6 and that adaptor? I ll need a level shifter? Thats adaptor dont have a level shfter? And also i saw that some resistors directlt soldered teensy for better signals. Resistors on the adaptor do same thing?

    Thx for your interests.

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    1. The OctoWS library does work with T3.6, the library doesn't not take advantage of the improved hardware to work better on one a 3.2 other than having more RAM

    2. FastLED is compatible, though do check the fastLED wiki for which special features you are trying top use. SoftwareSerial doesn't really work, since Teensy already has at least three hardware serial ports plus USB (Serial1 is hardware port 1,Serial is the USB you are used to). So you can probably swap out the software serial calls in your current code for Serial1 and have things work the same or better. To check libraries first install teensyduino https://www.pjrc.com/teensy/td_download.html and then select Teensy 3.6 under board type. The examples list will show the libraries that have known working versions for Teensy. Most other libraries will also work unless they try to use hardware unique to 8 bit arduinos.

    3. The OCTOws PCB is level converts and impeadance matching resistors, does work with T3.6 but is not mandatory if you have your own level converter.

    Would suggest that if coming from Normal Arduino you may be better with a couple of Teensy 3.2s since they are the ones generally used for LED work so most examples you find will be for them, not the newer T3.6. T3.6 will work but may need more tweaking. Do read the warnings on the OCto library and PCB page about current draw and other issues when building big LED installations since things get complex quickly, and do consider getting spare parts if you can afford to do so. You will probably learn something by damageing a board, and having spares makes it easier to prove what is broken, and allows you to keep moving.

    For

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    Hi. Its so nice of that u spend time for my questions which are mostly logical and less technical..

    for 1; i thinking on 3.6 for the clock speed and RAM. So 3.6 cld be good for Future ideas. No?

    And for 3; you know 3.5 is 5V tolerant but 3.6 is Not. I didnt realy get whats Tolerant in that case. It means i can send 5v signals with 3.5? Or i can take 5V signals Into 3.5 safely? I m confused Which one is tolerated? And Whats difference between 3.5 with 5v tolerant and 3.6 without 5v tolerant..and i dont need level shifter to down a 5v signal to 3.3v?

    And i didnt get why we cut something to use external supply. Yes i wil supply my leds and teensy with same external supply. So i need cut something? And if i cut how will u send new codes to teensy via pc? It just cuts the power to leds? Not the data flood from pc?

    And also i want to ask what tweaking i ll need if i get 3.6... and i ll need same tweaks if i get 3.5.. i no realy think to get 3.2 cus of speed and Ram

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    Re IC choice depends on what you write. I've never come close to running out of resources on a Teensy 3.2 and since they are cheaper and seem slightly more robust generally stick with them. If your ambitions are broad in scope (https://forum.pjrc.com/threads/46168...icrocontroller) you need the Teensy 3.6. If you have the money then a box of 3.6s will work but if still learning the 3.2 will run pretty much anything you find on the site, with the newer 3.5/6 you may hit things that don't work first time out.

    Re tolerance, the Teensy 3.5 can accept signals up to 5V and read them as logic high. It will only ever output 0-3.3V signals so may need up converting to 5V chips (most will work, read the data sheets to find out). The Teensy 3.6 is provably destroyed by applying 5V to the logic pins.

    Re external supply, you do not have to cut the trace but it complicates things not to. The trace is for 5V power, not USB data so that still flows. If you do not cut the trace and you connect your PC to USB and have LED power running you will have two different power supplies connected, and the higher one will feed current to the lower one, most likely from your LED power supply into your PC. Good engineering in the PC will hopefully prevent anything bad happening but when failure is 'computer blows up and/or catches fire' the advice will always be to isolate. If you don't then maybe nothing bad will happen but that would be very much your call. So aim is to have a common ground (having checked that you don't have a cheap PSU that puts 60V AC on the Gnd) and keeping the supplies separate.

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    1) i will not make a commodore 64 or something hehe but wow its realy broad as i said.. and buying a box of 3.6s. Haha that realy made me laugh. U jave nice sense of humor..

    2) as i got ; teensy 3.5 can accept and read signals correctly which is created by a 5v device..and also for other direction i ll use a logic level shifter.. am i true??

    3) for sure i wil connect teensy to computer via microUsb and on other end i ll connect led stripS to pins and i ll power that ledstrips with external power supply. So i ll not fee teensy power with that supply, but only the strips. So i need cut that trace? Am i right? I know how to connect arduino ground and leds power supply ground since i use arduno with usb connected to real time code compilinh and having strips woth external supply. Is it the same schematic with teeensy? Jusy to take a ground from led power suply to any gnd pin of teensy?

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    You have it with the level shifting, though depending on part you many read down to 3V as high so a test/read of data sheet can avoid extra hardware and complexity

    If your project will run from a PC you can also just leave the Teensy powered from USB and the LEDs from the power supply and move on. Any Teensy gnd will work, since if doing this right the only current flow will be logic signals and very low.

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    I ll use external supply for leds and power teensy via usb because i ll need to see the effects before i use same supply with leds which is external. But before this i need renew and test so i ll use usb attached to pc which also powers teensy but not just data flow. So i need cut that trace or no?sorry. Hehe..i l cut that trace when i ready tu build project and use 1 single supply for leds and teensy ?

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    Sorry. U said to cut the tracr and then u said not to.. i did t get..
    Last edited by stann; 10-02-2017 at 12:20 PM.

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    Senior Member+ MichaelMeissner's Avatar
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    Besides cutting the trace on the Teensy, another way is to have a special USB cable that connects the D+/D-/ground wires, but does not connect the 5v power line. Then you would have to use the external source to power your teensy when doing programming. Something like this product (which unfortunately is out of stock):


    But you could make your own. One way is to take two USB breakouts, and only connect all wires but the power, possibly putting a switch to optionally connect the power:


    Or just take a USB cable, strip off some of the sheathing and find the 5v line (typically but not always red colored) and cut it.

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    Click image for larger version. 

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    U see that i use a Gnd with the data line so.. so i need cut trace or no.. so i didnt get once u said cut and then u say no need .. confused

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    Above pic is same scheme i use with my arduino.. and it works safe.. i realy lost on cutting trace.. i completely no get why people designed teensy that way.. i can not move anything until i got how to POWER teensy and send codes while i power some leds Connected to teensy.

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    The Teensy is designed that way same as most other Arduino board intended for embedded operation to offer the choice of USB power or external power without them setting anything on fire. Rule is do not connect two sources of power to each other. How you do that depends on what you are doing, when I said you might not have to do it above, I also said this only applied if the project would always have USB power from PC for the Teensy. Which is what you have in your drawing and described above. So the + on the strip is not connected to +5V on the Teensy so everything should work.

    If you want to understand what is going one see top left of schematics here
    https://www.pjrc.com/teensy/schematic.html
    V USB 5V comes from the USB jack and normally goes through the two pads to 5V Vin and to the rest of the board.

    If you need to run without a USB connection you can cut the track between the two pads and seperate the USB power from 5V Vin. Or do As described my MichaelMeissner above with the USB cable.

    The reason you may not have met this before is the Arduino Uno has built in diodes similar to the ones shown here
    https://electronics.stackexchange.co...h-off-the-load
    Allowing the Uno to be powered from USB or external power seamlessley. This comes at the cost of increased price and a diode drop in the power to 4.5V

    Edit, Actually wrong on the Uno, seems it's got a comparator and switching arrangement to avoid the diode drop by activly selecting a power source.

    to circle back to your starting question - what you are already doing is correct and you can do the same with your Teensy without cutting anything.
    Last edited by GremlinWrangler; 10-02-2017 at 01:04 PM.

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    I saw the 2 pads om scheme. So i will not cut it as long as i connect teensy to pc via usb to Send Codes and of course to Power Teensy. But when my project ready to assemble and to add external suppy so i will cut this part and will be able to use same power supply for teensy and led strips? What if i do this without cut?

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    What you describe will work, but reprograming once the LED power is connected to Vin may be a problem. If LED power is on then you get supply conflict, if it is off then you have USB trying to power all your LEDs and probably failing.

    Certainly possible and simple, as long as you think things through if re-programing is ever needed.

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    I will not power leds with teensy 5v pin. Leds have their supply. And teensy connected to usb for power itself and data . Connection between teensy and ledsstrip is the Data cable and of course a Gnd from teensy to ledstrip to finish the electrical circle.. if thats wrong i better stay on arduino. And Also i dont know why teensy 3.5 has a 5v VIN! Its 3.3v board..i lost. Sorry.realy.

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    See above, your split power design will work and the same design decision will be needed with any Arduino type board that does not have the Uno's complex power switching system.

    Re 5V Vin, yes Teensy 3.X are all 3.3V board but USB power is 5V so they have an internal regulator (see schematic linked above) to produce 3.3V to make them easy to get started with.

    Does not effect anything you are doing but it's perfectly possible to make a design that is entirely 3.3V using a battery powered regulator if chasing the very lowest power drain.

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    So i m cutting out that plate when i work with usb or no cut? And on teensy there are several 3v and 5v pins.. which in VIN and which is VOUT. No documentation about this.

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    As per schematic the various 5V, 3V and gnd connections are connected to each other and depending on design can be used for either input or output. This design is up to you, and is this way to support flexibility in use rather than locking designs to a single function.

    If USB is connected and the track is not cut there will 5 V on the VIN pad that can supply up to 500mA
    If USB not connected or the track is cut then you can supply 3.6-6.0V into the Vin pin that will show up on all 5V labelled points and power the 3.3V regulator
    If ~5V is provided to the onboard regulator the 3.3V pins will output 3.3V up to 250mA.
    If you do not provide ~5V input (Nothing on the board uses it directly) you can supply your own 3.3V and the board will still work.

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    I didnt get the 3rd IF statement..what is if 5v provided to on board regulator. Its not same cutting track and using VIN to feed teensy and AT SAME TIME coding via usb?

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    The third statement is that as long as 3.6-6.0V comes from somewhere, the regulator will step it down to 3.3V. It doesn't care if that voltage is 5V USB or coming in the Vin pin. Achieve that by either means and you have 3.3V and the Teensy will run and talk on USB. They key part is you do need your grounds shared, which your drawing above is doing. USB port doesn't care if it's powering the connected device, as long as the device is powered from somewhere and share a common ground it will work.

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    For testing your LED project, the simplest way is to power the LEDs from power supply. Power the Teensy by the USB cable. Do NOT connect 5V power from the LED power supplies to the Teensy! Do not cut the VIN-VUSB pads.

    This way, the Teensy gets power from the USB. The LEDs have their own power supply.

    The only connection from the Teensy to the LEDs is the CAT5/6 cables. Each twisted pair has 1 signal and 1 GND. The GND wires connect to the LED GND close to the LED strips.

    There are many other possible ways, but too many ways is confusing when you are a beginner. Do it this 1 simple way. Get your project working. Only consider other possible ways after you have it working and you have learned more...

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    Thx guys for ur deep interest and time that u have spend for explanations. i will follow your suggestions and stay away from cutting things on board until my project is ready to assemble and give external power supply to teensy too after i see that code side is done ( means after i m done with pc to throw the codes and place my project to its place)

    Peace ..

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