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Unsure if PiTFT 3.5 and PiZeroW Pins are correct
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Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by rathian on Thu Aug 10, 2017 3:30 pm

I have no idea about electronics, but I'm supposed to build something for a friend.

I have a Raspberry Pi Zero W and a Adafruit PiTFT Plus 3.5" (2441) and was told I have to solder it first, otherwise the connections won't be connected sometimes and might fail.
I can flip the Raspberry in multiple ways to fit onto the PiTFT, but I have no idea which way it's supposed to get on.

So far I am only getting a white screen and want to make sure it's not hardware/pin related but a software issue before I start trying over and over again to fix it in raspbian.

Based on these two images:
http://lokspace.eu/wp-content/uploads/2 ... 24x496.jpg
and
https://cdn-learn.adafruit.com/assets/a ... ftplus.png

I assumed that the squared pin (Pin #1) on the Pi is supposed to go on the yellow squared bin on the pitft schematic, which would position the Pi in quite an awkward way, but whatever, I can 3D-Print a case around that.

So I've connected it like this now, Pin #1 seems to touch Pin #1.
http://i.imgur.com/79PIB65.jpg

I'm using a small pin-connection-thingie soldered onto the Pi to plug it into the PiTFT

Is it connected the right way around, or am I totally off here?
If not, how would I have read it correctly from the schematics?

rathian
 
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Re: Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by adafruit_support_carter on Thu Aug 10, 2017 7:02 pm

Can you post a photo of how your setup. That way we'll see for sure how you've got it hooked up. And what the "small pin-connection-thingie" is, etc.

adafruit_support_carter
 
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Re: Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by rathian on Fri Aug 11, 2017 5:56 am

Hello

The posted image https://i.imgur.com/79PIB65.jpg was already mine, this is how I have connected it.
I've downsized and attached the image to the forum.

IMG_20170810_211205t.jpg
IMG_20170810_211205t.jpg (91.92 KiB) Viewed 94 times


The connection-thingie seems to be called a GPIO header http://i.imgur.com/rpGWCFH.jpg
I got it bundled with thepihuts raspberry pi kit.

rathian
 
Posts: 3
Joined: Thu Aug 10, 2017 3:13 pm

Re: Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by adafruit_support_carter on Fri Aug 11, 2017 11:08 am

Sorry, missed the link to the photo in the first post. Unfortunately, you've got it hooked up wrong. You need to flip the Pi Zero over as shown in the image below. More unfortunately, this means you will need to unsolder the header pins on the Pi Zero and resolder them to the "top" of the Pi Zero.

pizero-to-tft.png
pizero-to-tft.png (765.79 KiB) Viewed 81 times


More information:
There are multiple models of the Raspberry Pi. The all have the 2 rows of pins, which are collectively referred to as the "GPIO header". GPIO = general purpose input / output and "header" is just the term for the place where you interface with hardware. Your first link in your first post was showing the functions of these pins (this is called "pin outs"). Here's another page I like to use:
https://pinout.xyz/
All of the current model Pi's have the same 2x20 set of pins and the pin outs are the same for all as well. But you do have to get the correct pin to the correct place. The Pi Zero is unique in that it is the only Pi in which the GPIO header pins are not already soldered on. This was probably done to keep cost low, but it also provides flexibility when using them in projects. But it can also create confusion for people just starting out. If you look at the other model Pi's, you'll see how they all have the header pins soldered to the "top" of the board. You've soldered them to the "bottom" of the board. This will result in transposing the two rows of pins. You've also got the Pi rotated - so yeah, it's inside out and backwards. :(

See if you can make the modifications I've described and try again. If you powered it up as shown, it's possible it has been damaged by the incorrect pin hook up. But I'm hopeful it will still work. Sorry for the confusion. Please report back as you progress.

And if my image and description doesn't make sense, let me know and I will try and clarify. Good luck!

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Re: Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by rathian on Fri Aug 11, 2017 12:41 pm

Darn it!

Thank you. I was already giving up why I just couldn't get it to work setting all sorts of configs in Raspbian.
I'll resolder and flip it around.

To add to that, the yellow squared marked pin on the schematics of the PiTFT board does not mark pin 1?
Or is Pin 1 not connected to Pin 1?

Flipping it over would make me believe the Pis Pin 1 is actually connected to Pin 2 of the PiTFT then, is that correct?

rathian
 
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Re: Unsure if PiTFT 3.5 and PiZeroW Pins are correct

by adafruit_support_carter on Fri Aug 11, 2017 3:26 pm

I think you're putting too much faith in the yellow outline. It's notionally a pin 1 indicator, but it's just part of the silk screen layer for the part that was used to create the layout. The real routing is different and a result of how the two parts come together. I think working with the smaller Zero form factor makes it more confusing. If you were working with one of the regular Pi's, the alignment would seem natural and obvious:
https://learn.adafruit.com/adafruit-pit ... i/overview

Pin 1 on the Pi though is a well known item. See the image you linked in your first post and the pinout.xyz link I provided.

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Please be positive and constructive with your questions and comments.