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marciokoko
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Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 10:28 pm

So I have a rpi2 using a bluetooth (hm10) serially-connected module to pins:

3v3
Gnd
Tx
Rx

I decided to add a touch lcd to the rpi2 so that I may control it via touch.

Well but the lcd uses a nice hdmi connector that holds the rpi2 flush against the back of the touch lcd. I could use an hdmi cable but the connector does two nice things:

1. Makes everything into 1 compact unit

2. Allows me to power both the rpi2 and touch lcd from one 5v/1.5A power adapter plugged I to the rpi2.

But the header pin that connects the rpi2 gpio pins to the lcd pins also blocks my access to the 3v3, Gnd, TX And Rx pins for the bluetooth hm10 module.

How can I get access to those pins? Here is a picture :
798B9B30-CD02-4CDB-A878-689458172B11.jpeg
798B9B30-CD02-4CDB-A878-689458172B11.jpeg (133.02 KiB) Viewed 373 times

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Imperf3kt
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Re: Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 10:59 pm

You can solder wires directly to the tabs you see below the connector as they connect to the GPIO.

Maybe this will suit your needs?
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 11:03 pm

OK but what about something a bit more study than just soldering wires?

Iow, what about some sort of header pin with solder pads at the bottom?

DirkS
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Re: Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 11:04 pm

Or solder e.g. a 26 pin box connector on the LCD https://www.google.co.uk/search?q=26+pi ... H6SRXuktmM:

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 11:11 pm

Thanks DirkS, now I know what to shop for. And just to be sure, I solder these legs down at the bottom to the pads on the lcd right?
D78945CA-8858-4695-AF40-5C5911E2B83E.jpeg
D78945CA-8858-4695-AF40-5C5911E2B83E.jpeg (160.6 KiB) Viewed 353 times

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Imperf3kt
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Re: Pins on rpi2 blocked by touch lcd connector

Mon May 14, 2018 11:26 pm

I don't think that would be any stronger since the tabs are not through-hole, but you can try if you want. Maybe add some hot glue after soldering for security?


As to where, yes, on that set of exposed tabs.
Before connecting anything, double check which pin is connected to which tab.

On my model (which looks very similar to yours) the tabs closest to the bottom of the board, align with the bottom edge of the connector which aligns with the top (I think) row of pins on the RPi.

Check to be sure, wrong conections usually proves fatal to your Pi.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

alphanumeric
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 1:31 pm

Have a look at this, https://shop.pimoroni.com/products/pico-hat-hacker Might do the job.

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 3:23 pm

Whoa!

So wait, I could presumable stick this between the rpi3 pins and the lcd connector and have access to the pins!? Not sure how it works...Something like this? {I saw the pic on the website but they're using it for something else}

Im thinking i would place this thing sandwiched between the pi (male) and the lcd (female) on the top side, giving me access to the bottom side set of holes with the labels.
Pico_HAT_Hacker_1_of_2_600x600.jpg
Pico_HAT_Hacker_1_of_2_600x600.jpg (39.76 KiB) Viewed 273 times

alphanumeric
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 7:13 pm

There are a couple of ways to use it.
One way is to solder a stacking header to it, female on bottom male on top. Then put it between your Pi and display. Then maybe put a 90 male on the other GPIO rows.
The other way to do it, like in the picture, is to solder it right to the Pi's GPIO header, down as low as you can get it. Then plug your display in on top of it. Your display will sit a little higher than normal. That will be the most compact way to do it.
I do the first option my self, usually with this, https://shop.pimoroni.com/products/protozero or this https://shop.pimoroni.com/products/ada ... i-mini-kit and a stacking header.

DirkS
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 8:04 pm

alphanumeric wrote:
Tue May 15, 2018 7:13 pm
One way is to solder a stacking header to it, female on bottom male on top. Then put it between your Pi and display.
But then you can't use the HDMI - HDMI connector that comes with the screen.
AIUI OP prefers to use that connector

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 8:46 pm

Wait, why couldn't I use the hdmi connector if I simply sandwich in the hat?

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Imperf3kt
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 8:55 pm

Because it lifts the screen 1.5mm away and then the HDMI to HDMI plug is out of alignment and won't fit.

Take a flat edge screwdriver and slowly and gently lift the plastic bit off the GPIO and stick the PICO hat (which is not a hat) in its place. Remember to neatly solder it in.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 9:13 pm

You just remove the black plastic frame (this one in the pic marked with the red arrows):
header.png
header.png (87.71 KiB) Viewed 218 times
Why do you emphasize soldering in the PICO hat? OH! Duh, well I would just need to solder in the 4 pins I need right?

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Imperf3kt
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 9:19 pm

Yes that plastic. It comes off but its a bit tricky, be careful not to scratch anything.
It is only friction fit. Nothing holds it on.

You can solder just the Pins you need, but while you're at it, why not future-proof yourself in case you ever decide to use more?
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

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marciokoko
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Re: Pins on rpi2 blocked by touch lcd connector

Tue May 15, 2018 9:34 pm

Ah yes! Good point.

Thanks for all the great tips...cant wait for that hat thing to get here

alphanumeric
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Re: Pins on rpi2 blocked by touch lcd connector

Wed May 16, 2018 9:05 am

Yes, sorry people, either one of my solutions will make plugging in that custom U shaped HDMI adapter tricky. I lost sight of that when mulling over my response. :oops:

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