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RA8875 Tutorial and Wiring Diagram
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RA8875 Tutorial and Wiring Diagram

by TheBearF8 on Thu Feb 27, 2014 7:20 pm

Is there anyway to get a Wiring diagram for the RA8875 to an Arduino UNO
I have the library downloaded and have the RA8875 connected to the 5" non-touch screen
But have NO idea how to connect this to the Arduino

Please

Thanks in advance
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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Fri Feb 28, 2014 9:56 am

Connect as described in the example sketches:
Code: Select all | TOGGLE FULL SIZE
// Connect SCLK to UNO Digital #13 (Hardware SPI clock)
// Connect MISO to UNO Digital #12 (Hardware SPI MISO)
// Connect MOSI to UNO Digital #11 (Hardware SPI MOSI)
#define RA8875_INT 3      //Connect INT to Digital 3
#define RA8875_CS 10      //Connect CS to Digital 10
#define RA8875_RESET 9      //Connect RESET to Digital 9

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Re: RA8875 Tutorial and Wiring Diagram

by TheBearF8 on Fri Feb 28, 2014 10:20 am

I have
Int connected to 3
Rst connected to 9
CS connected to 10
VIN to 5V
GND to GND

Running the textmode.ino

I keep RA8875 Not Found

What is wrong ?

Thanks in advance
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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Fri Feb 28, 2014 10:51 am

You don't have SCLK, MISO, and MOSI connected

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Re: RA8875 Tutorial and Wiring Diagram

by mimi123 on Wed Mar 16, 2016 2:12 pm

Does anyone know why I would not be getting any output in the serial monitor at all? The code uploads without any errors, but there's no output... I'm using an Arduino Leonardo so I'm not sure if that effects it.

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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Thu Mar 17, 2016 9:03 am

Try adding this as the first line of setup:
Code: Select all | TOGGLE FULL SIZE
while (!Serial);

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Re: RA8875 Tutorial and Wiring Diagram

by mimi123 on Mon Mar 21, 2016 12:39 pm

Does this need to be supplied with more power than just the 5v from the leonardo? I'm getting an output but instead of filling the screen like the code in the example buildtest says, I get stripes on the screen...

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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Tue Mar 22, 2016 9:25 am

Did you change the constant in the begin statement to match your screen resolution?
Code: Select all | TOGGLE FULL SIZE
 /* Initialise the display using 'RA8875_480x272' or 'RA8875_800x480' */
  if (!tft.begin(RA8875_480x272)) {
 

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Re: RA8875 Tutorial and Wiring Diagram

by Strakosha on Sun Apr 03, 2016 5:52 pm

Are there special instructions about same problem for arduino due?
No problem at compile time but display remains black. I have tried with buildtest and ts_calibration sketch examples.
Can you help me?

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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Mon Apr 04, 2016 8:47 am

How do you have it connected? Note that SCLK, MISO, and MOSI are NOT on pins 11, 12, and 13. They are only available on the 2x3-pin SPI header near the center of the Due.

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Re: RA8875 Tutorial and Wiring Diagram

by softweyr on Sat Oct 22, 2016 3:30 pm

I'm having the same problem, I can actually talk to the 8875 but nothing on the screen. What's the best approach to troubleshooting the screen? This is a brand new screen from AdaFruit, arrived last night.

UnoScreen8875.jpg
Screen, 8875 driver board, and Uno
UnoScreen8875.jpg (974.37 KiB) Viewed 639 times


Also, while I have the experts here, is the 8875 board 3.3v I/O tolerant? I'd love to be able run this off my Feather M0, but don't want to have to add a bunch of electronics to get all the I/O lines to 5v; I'll just use a Mega instead.

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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Sun Oct 23, 2016 12:50 pm

Looks OK. Can't see the ribbon cable connector in the picture. Are you sure that's solid?

It will run on 3.3V, but it's a bit flaky on my Adafruit Metro at least. I suspect that the voltage regulator isn't putting out enough current. A feather has even lower power output on 3.3V so, you'll want to power it from 5V or BAT The signal levels will still only be 3.3V, so you don't need any level shifting.

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Re: RA8875 Tutorial and Wiring Diagram

by softweyr on Sun Oct 23, 2016 8:07 pm

adafruit_support_rick wrote:Looks OK. Can't see the ribbon cable connector in the picture. Are you sure that's solid?


Not really, no. I did go back through the photos in the tutorial and I'm positive I have it right-side-up now. Just to be sure, I have the gold contacts on the end of the mylar ribbon facing UP when I insert it into the connector, then I close the connector by squeezing both ends of the movable bar into the body of the connector.

I get a flash from the screen when I plug in the Uno, but nothing beyond that. I don't want to RMA it if there's a way to troubleshoot and see if we can figure out if it's the screen or the module that's not working. I have a DSO at my disposal. I don't see any test points I can hit near the screen output, though.

Thanks for your help, I appreciate it. My confidence with mylar ribbons and squeezey connectors is pretty low.

UnoScreen8875-2.jpg
Uno + RA8875 controller + 4 in touchscreen
UnoScreen8875-2.jpg (148.25 KiB) Viewed 617 times

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Re: RA8875 Tutorial and Wiring Diagram

by adafruit_support_rick on Sun Oct 23, 2016 8:53 pm

It all looks right. Have you got Eagle? The schematics are here.
https://github.com/adafruit/Adafruit-RA ... -Board-PCB

As for your scope, you're interested in pins 30 through 33 of the 40-pin. You can probe the SMT leads. The flex cable indicates which end is pin 40

if the RA8875 is working, I believe you should see a regular pulse train on VSYNC or HSYNC. those are pins 32 and 33. I imagine you'll see lots of wiggling on PIXCLK, which is pin 30. Pin 31 is ON/OFF. Not sure about which way that one should be.

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Re: RA8875 Tutorial and Wiring Diagram

by softweyr on Tue Oct 25, 2016 2:51 am

adafruit_support_rick wrote:It all looks right. Have you got Eagle? The schematics are here.
https://github.com/adafruit/Adafruit-RA ... -Board-PCB

As for your scope, you're interested in pins 30 through 33 of the 40-pin. You can probe the SMT leads. The flex cable indicates which end is pin 40

if the RA8875 is working, I believe you should see a regular pulse train on VSYNC or HSYNC. those are pins 32 and 33. I imagine you'll see lots of wiggling on PIXCLK, which is pin 30. Pin 31 is ON/OFF. Not sure about which way that one should be.


Thanks! I'll look into next week, I'm on business travel most of this week. I'm wondering if it might be insufficient power, I'm just running the Uno off a PC USB port, and they're notoriously low on power. I'll get a real 5V power supply on this before breaking out the o-scope. Thanks for all the help!

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