ELEGOO 2.8 TFT shield for ARDUINO MEGA - turn off the blacklit or sleep mode

Other Hardware Displays
1

Hello Everybody.
I have been searching with no avail for way for turning the blacklit or force the whole display into sleep mode either via hardware modification but much better if via a software command.

It's installed as a shield so it vould be impossible ( I think) to drive the power on and off via a mosfet.

I hope somebody may provide some guidance here.
I am asking 'cause for an issue related to the SD card access on this forum I found an astounding and prompt support. I hope I can be that lucky once more.

Presently I am using the Elegoo libraries and not the Adafruit but that shouldn't be a limiting factor, isn't it?

Thanks in advance
Scud

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Post a link to the Display (and Adapter Shield) that you are using. Then you can get an accurate reply.

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This is a link for the display

It has been designed so that it installs directly on Arduino Uno or Mega pin-sockets. That's why I mentioned the shield

Thanks

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Thanks for the link. Yes, it should work fine.

Does it really have AMS1117-3.3 regulator ?
Does it have 74LVC245 buffers or 74HC245 buffers ?

The extra holes are seldom used. On a Uno all the GPIO is used for TFT and SD. Only A5 is spare and I don't think that A5 is routed to the "extra holes"

David.

5

Yep

I confirm the AMS1117 and 2 x 74HC245A as fa I can see. I can post picture but I don't know whether it might be useful. From the back side I fail to locate any eventual connection from 5V to the backlight LED, Actually I cannot clearly spot the backlight LED at all

6

Google Photos

link to the picture

7

Thanks for the feedback.

Many 3.5 inch "Blue Mcufriend" use 74LVC245
Most 2.8 inch and 3.5 inch "Blue Mcufriend" have AMS1117-3.3

Current Red 2.4 and 3.5 Mcufriend omit the AMS1117. Older shields had AMS1117
Very few Red Mcufriend use 74LVC

In an ideal world they would all use AMS1117 and 74LVC

David.

8

I wanted to try

tft.writeRegister8(0x28, 0) //supposedly turns the backlight off

just to see whether it has any essect at all but writeRegister8() is set as private in Adafruit libraries on which Elegoo libraries seem to be based. How can I make it public?

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Never mind! I found this one in the Elegoo library that may fit the bill and it is declared as public.

Anyway I have troubles at decyphering it since I am a novice.

void setRegisters8(uint8_t *ptr, uint8_t n);

I would guess that *ptr is some sort of pointer. I I write it as

tft.setRegisters8(0x28, 0);

I get an unspecified error during compilation.

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There is no register 0x28 on an ILI9325

There is no hardware for switching the backlight on your Blue Mcufriend.

David.

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understood
I was hoping in some hidden register but I haven't any reference to the hardware so I set myself on a wild chase completely blinded.
thanks

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