SPI 3.5 screen

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VeteranGamer
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Re: SPI 3.5 screen

Post by VeteranGamer » Wed May 15, 2019 9:58 pm

Marty33 wrote:
Wed May 15, 2019 5:56 pm
thank you very much for your feedback to you both

@VeteranGamer or @infinitLoop, if i don't use the SPI Adapter and 3.2" screen, you think i can wire your 3.5" version and use the GPIO Assist - Ultra ?


I’m not certain about how this GPIO Assist works...
I’ve always wired/connected directly to the RPi GPIO
(I’ve never found the need to buy these type of boards, but I can see how they can benefit novices)


However....
The main SPI connections for all these LCD will be the same (as the RPi only has certain SPI GPIO)...
But...
The 3.5” LCD will be using a 5V connection for powering the Back Light (LED) and LCD (out of the box)...
You may be able to move this to a 3.3V GPIO (I’ve always just wired the 3.5” LCD to 5V)
But
I always tend to remove the black block which is on the LCD board used for quick and solderless GPIO connections...
(it’s easily removed and lowers the profile of the LCD board)
This will then allow you technically to wire the LCD how you see fit...
But the SPI connections going to the RPi GPIO are pretty ridged/specific, so you only really have flexibility with the GND and maybe the 5V...



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infinitLoop
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Re: SPI 3.5 screen

Post by infinitLoop » Thu May 16, 2019 8:24 am

VeteranGamer wrote:
Wed May 15, 2019 9:58 pm
Marty33 wrote:
Wed May 15, 2019 5:56 pm
thank you very much for your feedback to you both

@VeteranGamer or @infinitLoop, if i don't use the SPI Adapter and 3.2" screen, you think i can wire your 3.5" version and use the GPIO Assist - Ultra ?
I’m not certain about how this GPIO Assist works...
the gpioassist just re-routes the gpio pins to more convenient, labelled pads/holes. the pro adds a usb hub to it and usb audio, and then the ultra adds in the power assist stuff (safe shutdown, boost, recharge) and the external connectors on top of that. it just makes for a nice clean build, in my experience, and cuts down on mistakes.

the gpioassist doesn't do anything for you, for the screen. it leaves the 8 pins that it uses for SPI unconnected to anything, so you could wire it directly like veteran says. you just have to do the pin/cable mapping and connections yourself.

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Re: SPI 3.5 screen

Post by infinitLoop » Thu May 16, 2019 8:30 am

VeteranGamer wrote:
Wed May 15, 2019 9:58 pm
I always tend to remove the black block which is on the LCD board used for quick and solderless GPIO connections...
is there something you can point to that explains that better? do you mean the black strip on the screen itself where the ribbon connector is? or are you just talking about the plastic gpio connector on the screen's control board?

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Re: SPI 3.5 screen

Post by Helder » Mon May 27, 2019 7:29 am

Just so everyone knows all 3.5inch SPI screens have a higher resolution 320x480 usually and because of this will be real laggy when using fbcp drivers. The juj driver might be better but if it's a Pi Zero it might now be powerful enough to do smooth video and run emulators well.
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