Teensy 3.2 + Prop Shield only updates LED's when I touch the MOSI Pin?

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maruska

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Pretty much what is says in the title...

I have a Teensy 3.2 with pins (DIY) and a Prop Shield with headers all around. I have some NeoPixels attached on the 5v, D, and G pins of the shield. It doesn't seem to matter what example code I run, the LED's only animate when my finger touches the MOSI pin. I've tried 1) adding a 300 Ohm resistor between pin 11 and MOSI, 2) shunting it to ground, 3) disconnecting the pin all together. Adding the SPI code for pin 7 doesn't seem to help either. The only thing that works is my finger... why? Any ideas?

J.
 
Sure thing. Been trying to debug what's going on with the MOSI pin on the back, so you can see the repeated soldering.

IMG_1274.jpg

IMG_1273.jpg

I've ordered a second set of boards and am soldering up those currently...
 
Also - would it change your opinion (it's a ground issue) if it were the MISO pin not the MOSI? (My fingers are big compared to the pins :confused: )

Running a simple Blink program on either pin 10 or 11 works fine (shield disconnected of course).
 
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Can you test the SPI pins by running some of the SPI Serial examples on the propshield flash (pin 6 LOW to access SPI flash)
https://github.com/PaulStoffregen/SerialFlash

If you have a scope or analyzer can you watch the output on the CLK and DAT pins on the shield with nothing else attached?
 
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So, I think this is a case of working with stale Neopixels from the parts bin.

I found this snippet of code from another forum post which seems to have fixed the issue...

Code: 
volatile uint32_t *reg;
reg = portConfigRegister(11);
*reg =PORT_PCR_MUX(2);

However, this seems to have disabled the audio portion of the shield, and seems to be permanent(?) - as in I need to some how undo this port configuration to get it back to a "stock" state?
 
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