Cheap UNO clone & cheap board connectors

Has anybody else had issues with an Arduino UNO clone and the electrical connection through the stacking headers to a shield?

Thus is my clone board:

I've had an issue that i've been trying to figure out all day and i've finally figured it out!

I've got an UNO shield with an Ambient Light & Progimity sensor on it as well as an RTC, both connected via the I2C bus. Everything works on the prototyping board so I transferred the design onto a prototyping shield.

And that's where it all started to go wrong!

The I2C bus didn't work. The I2C scanner couldn't find any devices.

I checked all the wiring on the prototyping shield with my multimeter and it all buzzed out ok, no shorts or breaks.

Attaching a logic analyser to the SDA and SCL pins revealed that the SCL pin was behaving correctly but the SDA did nothing, just sat there at a '1' all the time.

After tearing out most of my hair, I finally figured it out!

It seems that even when the male header pin on the shield is inserted into the female socket on the UNO clone, that does not mean there's an actual electrical connection!

And this is the connection that isn't really connected:

The upshot being that I need a supply of reliable single row through hole female headers and stacking male/female headers.

Any suggestions?


Buy a set of long tail female headers to stick between the two boards.

I have used a lot of those style of header sockets, mostly cheap ones from the far East.

They are relaible enough, very few failures.

If you want more re-assurance for reliability and qualtity, buy them from the likes of Farnell, Element14 or Digikey, its a simple choice really.

Thanks for the replies. My stacking headers were from an R3 header kit that looks just like those from Sparkfun, well at least they do externally.

It looks like I'm going to be better off in the long run buying a stash of single row stacking headers from Fsrnell.