[MinnowBoard] 1.6V output on gpio pin

[Anders, David]

Trevor,

It depends on how you have it connected and what the current draw is. Like many dev boards, the Max/Turbot is only designed to provide a very minimal current on the GPIO pins, generally around 7mA. You'll need to use a low current LED along with a current limiting resistor to make sure you don't exceed that value. 

Alternatively you can use a transistor to allow for higher currents. A good example of this can be seen in the Tadpole lure:

http://wiki.minnowboard.org/Tadpole_Lure

thanks
Dave Anders


-----Original Message-----
From: elinux-MinnowBoard [mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of Trevor Woerner
Sent: Friday, February 5, 2016 5:18 PM
To: MinnowBoard Development and Community Discussion <elinux-minnowboard at lists.elinux.org>
Subject: [MinnowBoard] 1.6V output on gpio pin

Hi,

WARNING: sw person doing hardware! ;-)

I was playing around with my MinnowMax and Turbot boards and wanted to do the hardware "hello world!" involving flashing an LED via a GPIO.

# cd /sys/class/gpio
# echo 338 > export
# cd gpio338
# echo out > direction
# echo 1 > value

At first I didn't think it was working (which is why I tried on both my MinnowMax and Turbot boards). When I double-checked with my DMM I noticed that it was working, but the voltage was really low, roughly 1.6V.

Is there something I'm doing wrong that I'm not getting 3.3V (or 5V)?

Best regards,
     Trevor
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