LPC1114 GPIO voltage levels

[lpcware]

Content originally posted in LPCWare by vladimirro on Sat Jun 20 13:07:18 MST 2015
Hello again

Let me introduce another problem I faced with LPC1114.
I tried to implement PWM and I noticed that the low state never reached 0V. It varied from 400mV to 600mV.

Then I set one of the GPIO to logic low and it turned out that my uC doesn't output 0V but 0,4-0,6V...
I couldn't find any information about voltage levels of GPIO in LPC1114 but I guess logic low should be 0V.
I probed the GND pin and it is 0V.

What can be a reason of such behaviour?

[lpcware]

Content originally posted in LPCWare by R2D2 on Sat Jun 20 15:20:35 MST 2015

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Quote: vladimirro
I tried to implement PWM and I noticed that the low state never reached 0V. It varied from 400mV to 600mV.
...
What can be a reason of such behaviour?

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Of course you should reach nearly 0V...

[img=660x397]http://www.lpcware.com/system/files/PWM_0.JPG[/img]

At least if your setup is correct, nothing is connected and your measurement equipment is working...