Newhaven Display Forum

Newhaven Products => TFTs => Topic started by: mole on February 27, 2017, 05:06:37 AM

Title: Pin reversal NHD-1.8-128160EF-CTXI#-FT?
Post by: mole on February 27, 2017, 05:06:37 AM
Toward the end of our product verification, I coincidently verified our design towards the image of the NHD-1.8-128160EF-CTXI#-FT (http://www.newhavendisplay.com/specs/NHD-1.8-128160EF-CTXI-FT.pdf)
I noticed that the image had the touch pins to the right hand side of the screen (when viewed with connectors pointing down and facing image side), while our design seemed to have them on the left hand side.
The picture of the module tells me that pin1 needs to be on the left hand side, but when I plug that into the suggested molex plug with contacts on top, the molex datasheet (http://www.molex.com/pdm_docs/sd/524352471_sd.pdf) suggest pin1 will be on the opposite side.
Attached is a collage of the two datasheets to indicate the problem.

Can you please confirm this is the case, or did I get something mixed up?

Title: Re: Pin reversal NHD-1.8-128160EF-CTXI#-FT?
Post by: Paul_B on February 27, 2017, 08:25:52 AM
Morning,

A common solution for determining cable wire numbering is to look at the displays FFC/FPC cable. As you can see in the image above if you define pin one at the arrow on one end of the molex connector then the cable routing demands that pin 1 be at the location of the opposite end. In your particular case pin 1 needs to be on the right hand side.
Title: Re: Pin reversal NHD-1.8-128160EF-CTXI#-FT?
Post by: mole on February 27, 2017, 10:03:03 AM
As a professional, I draw the plugs as a separate part using the manufacturers number, then the schematic application specific symbol using their numbering and connect the two. On some occations the manufacturer's numbering is not there, or missing, causing doubt and confusion but at least makes me aware about the doubt, but in this case they seems to be reversed, wich is even more confusing as I got no clear alert. I should note that it is not common for the professional designer to have the part in their hand before designing the pcb. In this case a simple picture put me on a lead, wich is not really giving much confidence. A picture is easy to mirror. But the picture (http://www.newhavendisplay.com//media.digikey.com/Photos/Newhaven%20Display%20Photos/MFG_NHD-1.8-128160EF-CTXI-FT.jpg) of this module at digikey didn't show a mirrored image and gave some confidence.

Luckily I accidentially found out about this mismatch before it was too late. I just needed a confirmation that the plug datasheet numbering was reversed to the TFT's datasheet pin numbering. I got reasons to doubt the TFT datasheet [because of poor electrical specs], so I thought I better get this confirmed. I know these chinese parts have poor datasheets in general so I should have been alert much earlier.

Title: Re: Pin reversal NHD-1.8-128160EF-CTXI#-FT?
Post by: Paul_B on February 27, 2017, 05:06:52 PM
The pin markings from the drawing are correct.  As for the mating connectors, defining “pin 1” is arbitrary.  Yes, some Molex connectors have a small arrow/marking showing where “pin 1” is, however this pin 1 designation does not correlate with our products.  The “match” is irrelevant because the connector will work 100% the same if a device’s pin 1 is on the opposite side of where it says “pin 1” should be. I understand it helps in cases where a simple pass-thru FFC is used, to help know what side of the cable should be where, however with our display products designed onto a board there would be only one way to insert the cable.