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Thread: Teensy 3.2, Prop Shield LC, DotStar 60/m strip (2m)

  1. #1
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    Teensy 3.2, Prop Shield LC, DotStar 60/m strip (2m)

    Hello,

    I am using the Teensy 3.2 microcontroller and the Prop shield to drive the LED strip. All of the other functions with the Teensy I have programmed work very well. I added the prop board by using stacking headers.

    When I load the simple example code into Arduino IDE, and upload it to the Teensy, absolutely nothing happens. Not a single LED turns on, I have made sure the strip has 5v power and that the CLK/DAT pins are going to the Prop board correctly. I verified that the IN (start) of the strip is what was soldered with the pre-attached 4-pin wire harness. I even tried using an external 5v supply with common ground, but nothing.

    The code I am using was taken from https://www.pjrc.com/store/prop_shield.html The page gives detailed example of how to simply use the Prop shield with DotStar LED strip, including pictures and the code below. Please help me to verify everything was done incorrectly.

    Also, when I compile the program, I do get an error, I tried using both the build-in library and installing FastLED library using 'Manage Library'. Both return same error, show below:

    Code:
    C:\Program Files (x86)\Arduino\hardware\teensy\avr\libraries\FastLED/FastLED.h:17:21: note: #pragma message: FastLED version 3.001.008
    
     #    pragma message "FastLED version 3.001.008"
    
                         ^
    
    Opening Teensy Loader...

    Thanks

    Stephen G.

    Code:
    #include <FastLED.h>
    
    #define NUM_LEDS 120
    CRGB leds[NUM_LEDS];
    
    void setup() {
      delay(2000);      // sanity check delay
      FastLED.addLeds<APA102, BGR>(leds, NUM_LEDS);
      pinMode(7, OUTPUT);
      digitalWrite(7, HIGH);  // enable access to LEDs
    }
    
    void loop() {
      // Move a single white led 
      for(int n = 0; n < NUM_LEDS; n++) {
        leds[n] = CRGB::White;
        FastLED.show();
        delay(8);
        leds[n] = CRGB::Black; 
      }
    }
    Last edited by s1godfrey; 03-03-2019 at 03:58 AM. Reason: bug show in Arduino

  2. #2
    Senior Member pictographer's Avatar
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    Have you calculated the current draw of the LED strip? 120 RGB LEDs can draw quite a lot more than the typical 5v phone charger supplies.

  3. #3
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    Quote Originally Posted by pictographer View Post
    Have you calculated the current draw of the LED strip? 120 RGB LEDs can draw quite a lot more than the typical 5v phone charger supplies.
    Thank you for your reply.

    The external power supply was used to account to this, which has 4A @5V when I first setup my project. However, the test program only turns on a single LED at a time, so the current draw in practice would only be a a few mA. From Adafruit's guide: "Estimate up to 60 milliamps peak for each pixel at full brightness white". In order to change code without altering power sources, it was more practical to use the USB power when using test code like this and so long as only one or two LED's were turn on at once.

    I have also posted same topic on Adafruit's site, but wanted to make sure I covered all options. Since the prop board and the teensy are stacked, with teensy on top and other programs operate successfully, its most likely I was the lucky number 12 winner of a defective strip. These strips are actually 4 joined sections of 30 LED strips. So, depending Adafruit's response and return policy, I didnt want to break them apart, because their wrapped in clear plastic and sealed. I would have to break that to take out a single section for testing.

    I did measure at the very end of the strand with a multimeter and read 5V output, so this means there is no break in power. I don't have an oscilloscope to validate CLK or DAT present.

  4. #4
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    Ok then.. So, I still could not handle the case in which an entire strip of LEDs were somehow bad. I searched more on Adafruit's site and found:

    "Confirm the Arduino is connected to the INPUT end of the strip. If your strip came with a plug pre-soldered, there is only a 50/50 chance this is the correct end. Examine the strip closely, and solder wires to the INPUT end if needed."

    With that information I looked much closer at the strip CI/DI - CO/DO stencils. The pre-wired end was covered in white film, masking the CO/DO at the very first Pixel connection. The far end extended beyond the protective film, whereby the CI/DI was also masked. When I cut back the far end, it became clear that the wrong end was pre-wired. Note: There were no arrows or other indicators showing the flow direction.

    So, yep, when I soldered some leads to the correct input side, it worked straight away. A whole night of frustration due to incorrect wiring by the Vendor! On a positive note, I don't have to worry about refunds, shipping cost or long shipping time to get a new strip!

    Thanks so much, maybe this can provide a lesson to other newbies out there. LOL...

  5. #5
    Senior Member pictographer's Avatar
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    Good for you for solving it and reporting back! Looking forward to pictures or videos. :-)

  6. #6
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    Quote Originally Posted by pictographer View Post
    Good for you for solving it and reporting back! Looking forward to pictures or videos. :-)
    Once the LED strip was connected correctly, adding it to the project was a simple matter of adding the CLK/DAT pins to the output of the Prop shield and using an awesome MIDI host board by Hobby Electronics: http://www.hobbytronics.co.uk/usb-host-midi

    https://photos.app.goo.gl/PgL12vuMW2kBdKtr5
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