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3.5" display that have extra GPIO pins for use

Posted: Thu Oct 03, 2019 12:47 pm
by UserNam3r
Hi,
I'm looking for 3.5" display for raspberry pi 4 that can have free GPIO pin that are available to use, Some displays use <40 GPIO pins but the free GPIOs are not avaliable, If you know such display please comment,
Thanks.

Re: 3.5" display that have extra GPIO pins for use

Posted: Thu Oct 03, 2019 7:05 pm
by gordon77
This one?

https://thepihut.com/products/adafruit- ... qwEALw_wcB

The display uses the hardware SPI pins (SCK, MOSI, MISO, CE0, CE1) as well as GPIO #25 and #24. GPIO #18 can be used to PWM dim the backlight if you like. All other GPIO are unused. There's a 2x13 'classic Pi' connection GPIO header on the bottom, you can connect a 26-pin Pi GPIO cable to it to use any of the other pins as you like. The other GPIO are broken out into solder pads at the bottom, in case you want to use more of the GPIO.

Re: 3.5" display that have extra GPIO pins for use

Posted: Thu Oct 03, 2019 7:35 pm
by alphanumeric
If you mount a Proto Hat https://www.adafruit.com/product/2310
with a stacking header https://www.adafruit.com/product/1979
Between your Pi and display you can access any unused GPIO pins.
You'll also need these standoffs https://www.adafruit.com/product/2337

Re: 3.5" display that have extra GPIO pins for use

Posted: Thu Oct 03, 2019 8:04 pm
by FTrevorGowen
alphanumeric wrote:
Thu Oct 03, 2019 7:35 pm
If you mount a Proto Hat https://www.adafruit.com/product/2310
with a stacking header https://www.adafruit.com/product/1979
Between your Pi and display you can access any unused GPIO pins.
You'll also need these standoffs https://www.adafruit.com/product/2337
Or, should you wish to use multiple, "non-clashing" HAT's or other things, there's the PHAT STACK which, FWIW, I've used here: http://www.cpmspectrepi.uk/raspberry_pi ... Stack.html
Trev.

Re: 3.5" display that have extra GPIO pins for use

Posted: Fri Oct 04, 2019 9:24 am
by alphanumeric
I have one of the original Black Hat Hack3r boards and a couple of the Mini Black Hat Hack3r boards, the pHat stack is on my wish list for future purchases.
https://shop.pimoroni.com/products/mini ... 8025991

If you solder a female header on the bottom side of a Pi Zero, you can plug it into the pHat Stack like it was a pHat and it will work just fine. No having to use the ribbon cable. Just plug it into the front most header to get access to the power jacks etc. Or use a female 90 header so its standing up with the jacks pointing skyward. Then plug it into the rear most header. The one the ribbon cable plugs into.

EDIT: If you get the solder yourself version there are all kinds of options as shown in the pictures posted in the link in the previous post.

Re: 3.5" display that have extra GPIO pins for use

Posted: Fri Oct 04, 2019 10:47 am
by hippy
UserNam3r wrote:
Thu Oct 03, 2019 12:47 pm
I'm looking for 3.5" display for raspberry pi 4 that can have free GPIO pin that are available to use
In all my web-wanderings I have not seen any large LCD boards for a Pi which do not have the screen blocking use of at least 26 GPIO pins. It might be possible to fit one of those and access the others using a ribbon cable but there would be no 5V or 3V3 rails available on that.