The PIC and / or AVR anda GLCD need to be analysed to answer the question. The operating voltage of the PIC or AVR are easily determined. The GLCD, I use this term to cover all and any device with graphical LCD and/OLED capabilities, can vary from 2.8 to 5.00.
Have you seen my recent analysis of one specific GLCD?
Analysis is key. Operating the GLCD at the appropriate voltage is critical. Use voltage leveas as appropriate, and, be careful by starting at 2.8 and increase if you don't know the operating voltage of the GLCD.
But, stay away from the ST7735. They are the worst to get the correct voltage.
Anobium
...Stan... your experience is the best... please join in
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
The ili9341 can come in different sizes and voltage.
Ones from ebay-China use 5V for the vcc supply and the led back light. Reset can be tied to 5V instead of pic/avr pin.
All data and clock spi are 3.3V logic. I use a 8 channel logic level converter when running a pic or avr at 5V to drive ili9341.
I found I could run a 18f25k22 at 3.3V and then connect the data spi directly to the display..works fine.
I did not try running avr 328p at 3.3Vas this lowers the clock speed to 12 from 16 and might be unstable but there are 3.3V avr boards.
If you buy an ili9341 from Adafruit or other named supplier it will cost 3 to 4 times the price but may have 5V logic levels. Check when buying.
Using a logic level converter is more wiring and needs 5V and 3.3V supply. see attached photo.
The lower board is a nano with logic level converter. The other a pic running at 3.3V.
I think the ili9341 Anobium uses is 5V logic from what he posted once.
" My GLCDs range from 2.8 to 5. It just depends on who sent it to me. it is always fun sorting out the operating voltage."
It's not fun for me!
It is worth pointing out as I assumed the display used 5V logic. Took a while to work out why it wasn't working.
I bought some ddr2 pc ram from ebay-China, cost £12. Didn't fit. To send back to China is £9.50.
Also bought same ram and that didn't fit but there was a free retun label you have to print.
So check when buying if it's duff then is it free to return.
I have bought faulty displays from ebay and not sent them back.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Thanks for the rapid and detailed response, I'll go for 3.3v on both and see what happens. For future reference I appear to have the version with the unpopulated touch IC, a discret transistor (backlight?) and a regulator (3.3v?)
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I have that PCB attached to the an ILI9341. My is tested and validated at 5v.
But, start at 3.3v and raise to 5v. Using a standard test look for bleeding of colors at the lower voltages (see the attachment for typically low voltage bleeding).
Nice looking demos, what voltage do you run the PIC and the LCD at?
Very good question.
The PIC and / or AVR anda GLCD need to be analysed to answer the question. The operating voltage of the PIC or AVR are easily determined. The GLCD, I use this term to cover all and any device with graphical LCD and/OLED capabilities, can vary from 2.8 to 5.00.
Have you seen my recent analysis of one specific GLCD?
Analysis is key. Operating the GLCD at the appropriate voltage is critical. Use voltage leveas as appropriate, and, be careful by starting at 2.8 and increase if you don't know the operating voltage of the GLCD.
But, stay away from the ST7735. They are the worst to get the correct voltage.
Anobium
...Stan... your experience is the best... please join in
The ili9341 can come in different sizes and voltage.
Ones from ebay-China use 5V for the vcc supply and the led back light. Reset can be tied to 5V instead of pic/avr pin.
All data and clock spi are 3.3V logic. I use a 8 channel logic level converter when running a pic or avr at 5V to drive ili9341.
I found I could run a 18f25k22 at 3.3V and then connect the data spi directly to the display..works fine.
I did not try running avr 328p at 3.3Vas this lowers the clock speed to 12 from 16 and might be unstable but there are 3.3V avr boards.
If you buy an ili9341 from Adafruit or other named supplier it will cost 3 to 4 times the price but may have 5V logic levels. Check when buying.
Using a logic level converter is more wiring and needs 5V and 3.3V supply. see attached photo.
The lower board is a nano with logic level converter. The other a pic running at 3.3V.
I think the ili9341 Anobium uses is 5V logic from what he posted once.
My GLCDs range from 2.8 to 5. It just depends on who sent it to me. it is always fun sorting out the operating voltage.
Remember, I have a few here. And, in my mail tray here - I have a few more and my guess they will be a very wide range of voltages.
" My GLCDs range from 2.8 to 5. It just depends on who sent it to me. it is always fun sorting out the operating voltage."
It's not fun for me!
It is worth pointing out as I assumed the display used 5V logic. Took a while to work out why it wasn't working.
I bought some ddr2 pc ram from ebay-China, cost £12. Didn't fit. To send back to China is £9.50.
Also bought same ram and that didn't fit but there was a free retun label you have to print.
So check when buying if it's duff then is it free to return.
I have bought faulty displays from ebay and not sent them back.
My first use of ili9341 I used resistors....like https://randomnerdtutorials.com/how-to-level-shift-5v-to-3-3v/
Two 240x320 ili9341 but different size.
Thanks for the rapid and detailed response, I'll go for 3.3v on both and see what happens. For future reference I appear to have the version with the unpopulated touch IC, a discret transistor (backlight?) and a regulator (3.3v?)
@George/ Pictures speak a 1000 words....
It certainly does.
That is a photo of the sales page. That may arrive or be very different in terms of the PCB.
Can you confirm the PCB is what you have? I would not trust a sales page... you may even get a different chipset when it arrives!
" For future reference I appear to have the version with the unpopulated touch IC"
hmmm? maybe that's why I never got the touch screen to work!
@Anobium I hear what you say re. sales page pictures but in this case it is correct.
Last edit: George Towler 2019-11-10
I have that PCB attached to the an ILI9341. My is tested and validated at 5v.
But, start at 3.3v and raise to 5v. Using a standard test look for bleeding of colors at the lower voltages (see the attachment for typically low voltage bleeding).
Good luck.