Excellent, that did the trick. Thank you for the link/info.
mad_ady wrote:The problem with the xu4's gpio pins is that they operate at 1.8V and that is not enough to trigger a regular relay.
Yes, I'm aware of that. That is why I'm looking at the step-up USB converter to solved this exact issue.
mad_ady wrote:otherwise you'll also need a transistor and two resistors to increase the command voltage.
I have seen drawings in my various googling's, but I haven't quite been able to figure out how to go by doing this.
I would call myself relative good at soldering and I know my way around resistors and other simple stuff like that. Though I have never been any good at how transistors work other than it's a form if mini switch.
I bought the step-up USB converter today. It works as advertised and delivers 5V from eg. a AA battery just fine, but it looks like the GPIO just don't deliver enough amps to make it work.
I can see that the GPIO is working and it's delivering 1.8V when I connect CON11, pin 2 (ground) and 4 (I2C_5.SDA) and execute the the following commands. So far so good.
Code: Select all
echo 187 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio187/direction
echo 1 > /sys/class/gpio/gpio187/value
echo 0 > /sys/class/gpio/gpio187/value
When I connect the step-up alone the voltage stays at 1.8V on the GPIO side and goes to 5V on the USB side, BUT when I connect a small fan or the USB-Relay the voltage drops to about 0.5V - My conclusion to this is that the XU4 doesn't deliver enough amps, does this sound about right?
Any good advice on how to proceed?
Is it possible to "bundle" two GPIO ports, to deliver 2x the amps? Like GPIO 187 and 188, and then turn them both on? Or maybe that would just fry it?
Any ideas are welcome.