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3787 1.54" TFT ...no Docs?
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3787 1.54" TFT ...no Docs?

by adna on Mon Feb 18, 2019 3:05 pm

Greetings.
Normally the documentation at Adafruit is stellar, but I'm knocking my head on this one:

There seems to be _nothing_ on the project page except links and tutorials for _other_ TFTs with different
pin configurations. In the New Products video announcing adafru.it/3787, the demo shows what looks like
7 pins connected. But in the example code for ST7735/ST7789 only 2 or 3 pin connections are described
including MOSI, SCLK, CS and various pins that don't appear labelled as such on the 1.54" TFT.

I just need the simplest: What are the pin outs connected in some example code.
There's no documentation of how to hook this up to, for example, a Feather Wing, Arduino, etc.
Can anyone please point me to a paragraph or a photo that says:
"Hook up these pins from the TFT to (whatever Feather, Arduino, Metro...) and run this code.
Can anyone point me to docs for this product?
Thank you!

adna
 
Posts: 4
Joined: Sat Mar 26, 2011 9:09 pm

Re: 3787 1.54" TFT ...no Docs?

by adafruit_support_carter on Tue Feb 19, 2019 12:08 am

The Arduino library will be this one:
https://github.com/adafruit/Adafruit-ST7735-Library
which you can install through the Arduino Library Manager by looking for "Adafruit ST7735 and ST7789 Library"

The basic example there has the following wiring:
https://github.com/adafruit/Adafruit-ST ... st.ino#L38

Since this example works for multiple boards, you'll need to uncomment this line for the 1.54" TFT:
https://github.com/adafruit/Adafruit-ST ... st.ino#L52
(and comment out the one a few lines up)

Similarly here:
https://github.com/adafruit/Adafruit-ST ... st.ino#L83

The 2 or 3 pins mentioned are in addition to the hardware SPI pins which carry the actual display data. In summary (using front labels):
Vi to 3.3v or 5V, whichever matches your board
G to GND
CL to your boards hardware SPI SCK pin
SO to your boards hardware SPI MISO pin (only needed for using SD card)
SI to your boards hardware SPI MOSI pin
TC to digital 10 (or change in code)
RT to 9 (Or set to -1 and connect to Arduino RESET pin)
DC to 8 (or change in code)
CC only needed if using the SD card
BL only needed if you want to control backlight

You can see an example hook up to an Itsy Bitsy M0 here:
https://cdn-shop.adafruit.com/1200x900/3787-07.jpg

adafruit_support_carter
 
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Joined: Tue Nov 29, 2016 2:45 pm

Re: 3787 1.54" TFT ...no Docs?

by adna on Tue Feb 19, 2019 5:12 pm

Thank you so much for the prompt reply!
I uncommented the appropriate lines, and thanks to you was able to finish wiring.
(Is there really no documentation online to let someone know that the "TFT_CS" pin in the code is referring to the 1.54" pin "TC"?
Maybe that's obvious to people who do more work with TFT displays...)
The image at: https://cdn-shop.adafruit.com/1200x900/3787-07.jpg unfortunately isn't very helpful because some wires are obscured.
(Which blue wire goes where and where the orange one goes... can't tell.)

Still, using "OPTION 1 (recommended)" I only got a blank (dark) screen, though the backlight was lighting.
Same wiring, but in software, using "OPTION 2" however, works fine.

The last two pins are still mysterious as well. You said "CC" is only needed if using the SD card, and "BL" only needed to
control the backlight. So if one _does_ want to use the SD card and control the backlight, what do these pins connect to?

Also, is there any example online that show usage of the 1.54 TFT using circuitpython instead of the Arduino IDE?

Thanks again, so much!

adna
 
Posts: 4
Joined: Sat Mar 26, 2011 9:09 pm

Re: 3787 1.54" TFT ...no Docs?

by adafruit_support_carter on Tue Feb 19, 2019 7:35 pm

The documentation could be better. I think in this case it was item that was close enough to existing displays that is was hoped the current documentation would be enough. The labels on the back are a little less terse.

So if one _does_ want to use the SD card and control the backlight, what do these pins connect to?

Any available digital pin. CC = SD Card Chipselect. The display and the SD Card both use SPI for communications. The chip select pin is what is used to indicate which device should be listening to what is on the SPI bus.

Also, is there any example online that show usage of the 1.54 TFT using circuitpython instead of the Arduino IDE?

Any available digital pin. BL = BackLight. If the pin can do PWM, then you can control brightness. Otherwise it will just be on/off control.

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Re: 3787 1.54" TFT ...no Docs?

by adna on Tue Feb 19, 2019 7:43 pm

Awesome, thanks.

Are there Circuitpython examples for the 1.54"?

adna
 
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Joined: Sat Mar 26, 2011 9:09 pm

Re: 3787 1.54" TFT ...no Docs?

by adafruit_support_carter on Tue Feb 19, 2019 7:52 pm

Display stuff is currently in work for CircuitPython. It will become available initially in 4.0 (currently in beta) and expanded after that. Stay tuned.

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Please be positive and constructive with your questions and comments.