3.5" TFT screen for PI
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3.5" TFT screen for PI

by supallama on Wed Dec 26, 2012 8:27 pm

I have purchased this screen, in one picture for this product: https://www.adafruit.com/products/962 has the screen running off the PI itself, what pins do I connect the Red and Black wires to, to replicate this?
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Re: 3.5" TFT screen for PI

by adafruit_support_rick on Wed Dec 26, 2012 11:46 pm

That link is for a battery, not a TFT screen. What screen are you trying to attach to the pi? The only 3.5" tft we have is this one, which requires 6-15 VDC, and cannot be powered directly from the PI.

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Re: 3.5" TFT screen for PI

by supallama on Thu Dec 27, 2012 12:12 am

in one of the example pictures, it has a screen connected to the GPIO pins.
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Re: 3.5" TFT screen for PI

by adafruit_support_rick on Thu Dec 27, 2012 9:44 am

Can you post a link to the particular display you're referring to? The 3.5" display I linked to earlier has NTSC input, which connects to the composite video output jack on the Pi. It does not connect to GPIO. The red and black wires on that display are power and ground, which must be connected to an external power supply, not to the Pi.

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Re: 3.5" TFT screen for PI

by supallama on Thu Dec 27, 2012 10:47 am

here is the picture from the battery example pictures, the screen is connected directly to the GPIO pins for POWER. here is the link to the screen I have: https://www.adafruit.com/products/913
Attachments
ex1.jpg
black and red wires connected to GPIO pins to POWER screen
ex1.jpg (22.35 KiB) Viewed 655 times
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Re: 3.5" TFT screen for PI

by adafruit_support_rick on Thu Dec 27, 2012 11:04 am

The screen in that picture is a different device. PID 913 needs a 6-15VDC power supply connected to the red and black wires, which the Pi does not provide on the GPIO pins.

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Re: 3.5" TFT screen for PI

by svinzant on Thu Dec 27, 2012 2:34 pm

And... it's not connected to the GPIO pins via the ribbon cable.
I'm not sure what that's about, but it is somewhat misleading as it does look as though it is connected as you describe.
The image shows the display powered up but there is no connection to the red and black power wires. (Hello? Photoshop...)
The composite video connection is made to the RPi through a Male to Male RCA "gender changer" as it should be, but the power wires will need to be connected to an external power supply of the correct voltage and current.
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Re: 3.5" TFT screen for PI

by pburgess on Thu Dec 27, 2012 3:37 pm

I wasn't involved in the photo, so this is just speculation, but it sure does look like the display is connected to the ribbon cable. I suspect it's being run off the 5V line...though this is below the display's nominal rated 6V minimum, in some cases this might work (at the expense of reduced backlight brightness). It's really close to the edge though, and might be relying on the +/-10% variance in power supply output (i.e. could be 5.5V).
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Re: 3.5" TFT screen for PI

by adafruit on Thu Dec 27, 2012 3:37 pm

for that photo we're powering the display from the 5V/gnd pins on the GPIO header, this isn't suggested as some displays don't run off of 5V and also there's a risk of plugging in the wires wrong. Instead, we suggest one of our 9V adapter or a 9V battery pack
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Re: 3.5" TFT screen for PI

by supallama on Thu Dec 27, 2012 10:30 pm

Thank you pburgess and adafruit for clearing this up with me, and actually reviewing the picture attached. problem solved.
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Re: 3.5" TFT screen for PI

by svinzant on Fri Dec 28, 2012 11:42 am

for that photo we're powering the display from the 5V/gnd pins on the GPIO header

I stand corrected.
How much current can the GPIO +5V pin source?
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Re: 3.5" TFT screen for PI

by adafruit on Fri Dec 28, 2012 2:48 pm

it is connected directly to the microUSB cable port - check your power supply to know what the power limit is
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