LPC1114LV Uart low or 0 signal not GND!

[lpcware]

Content originally posted in LPCWare by johnnyfp on Sun Oct 19 22:05:57 MST 2014
Hi,

I'm trying to program a LPC1114LV using the ISP and UART interface and finding that when the UART communicates it's LOW or zeros are infact around 0.6mV.  Is this normal?

It's causing all sorts of headaches with various serial connectors that seem to think anything above 0.3mv is a 1.

Cheers

[lpcware]

Content originally posted in LPCWare by johnnyfp on Tue Oct 21 11:29:55 MST 2014
No I ment 0.6v or 650mV. :p

And I sort of solved the problem. How very very embarassing, As a single solitary via was missing from pin 21 to ground! of all things. I think I would have liked it just to not have worked, so discovered this issue when revisiting the layout to gain access to the SWD port. But because I had the ISP line tied to ground it was enough to let the MCU run, unstable as it was but it was running and responding to the autobaud symbol.

As the old saying goes, Measure twice, cut once.

Anyway thanks for your help. Time to sort out that pesky via.

[lpcware]

Content originally posted in LPCWare by 1234567890 on Mon Oct 20 13:13:02 MST 2014

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Quote: johnnyfp
... the UART communicates it's LOW or zeros are infact around 0.6mV.  Is this normal?

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Do you really mean mV? Or V?
Well, 0.6 mV is nothing. I can't imagine that this homeopathic voltage can disturb or influence a UART.

[lpcware]

Content originally posted in LPCWare by LabRat on Mon Oct 20 12:10:55 MST 2014
Use something with FT232 inside...

https://www.sparkfun.com/products/718

[lpcware]

Content originally posted in LPCWare by johnnyfp on Mon Oct 20 11:55:39 MST 2014
Ah ok, I made the assumption (my mistake) that a maximum value, includes all the specification limits and tolerances.

So can you recommend any USB2Serial converters that can be used to program this and doesn't cost the earth, or am I stuck with JTAG and LPC-Link 2?

[lpcware]

Content originally posted in LPCWare by NXP_Paul on Mon Oct 20 06:06:04 MST 2014
Johnny
According to the LPC111xLV data sheet, VOL=0.4V maximum (1.65 V < VDD < 1.95 V; IOL=3mA), so if you are measuring 0.6mV, then it is within specification limits.

Paul