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migry
01-17-2014, 12:04 AM
I have previously bought a teensy3.0 and done nothing more than install the teensyduino software and compile and download the LED blink program.

More recently I bought a teensy3.1 having seen that there is now a DAC output - very useful to me. I installed the latest version of teensyduino, compiled and downloaded the LED blink sketch (having modified the LED pin number!), but nothing. Using a scope I do see that the corner pin (number 13) is toggling high and low. Using my multimeter I have established that one end of the LED connects via the 470 ohm resistor to gnd and the other end of the LED connects to pin 13. Using the multimeters diode test I even see a value of .842 (suggesting that there is a diode), but there can't be enough voltage from the meter to light the LED.

I poked a 3mm red LED across the SMD LED and this red LED blinks.

So either the SMD LED is back to front, or upside down.

Thought it worth letting you know in case this isn't an isolated incident.

I can live without the LED as I have no way to replace it.

--Gary

stevech
01-17-2014, 01:43 AM
with power off, your meter's ohms scale should allow you to determine if the LED is open or installed backwards. Or maybe not soldered properly by a robot!