[SOLVED] Arduino mega +ssd1963 Problem

[sreepss]

Arduino mega +ssd1963 Problem
Hi all.. I have designed a custom PCB with ATmega2560 for my project. Have a 4.3 inch tft on it
With SSD1963 controller (16bit data bus). All the data and control lines are translated to 3.3 logic
With 74ahc541 buffers. The connection from my PCB to display module is via a 40pin flat ribbon
Cable. Earlier I have tested the display using mega board and all the codes are working fine. But whenever I have assembled on this board, the tft gives only white screen. I have a pullup in the reset line. Really fed up with this issue.

- - - Updated - - -

heres my schematic

 

[ud23]

double check the your data and address line connection same as per your code which was working.and check the tft lcd supply capacitor with specified in its datasheet.

Mostly miss match gpio in hardware and your c code.

 

[sreepss]

double check the your data and address line connection same as per your code which was working.and check the tft lcd supply capacitor with specified in its datasheet.

Mostly miss match gpio in hardware and your c code.

Yeah was exactly the same problem that you had mentioned, but I have resolved it earlier. Sorry to mark this thread as solved. And I have one more doubt, is it really required to give pullupa on my 74AHC541 output?

 

[ud23]

not necessary that pull up at output of 74hc541. your problem solved or still having problem with display.

 

[sreepss]

Its solved

 

[KlausST]

Hi,

Don't let inputs floating: D7 of U28. --> connect it to GND.

Is T_CS input or output?

***
Why the LED_A connection.

*****

I don't like the GND switching.
* The input signal are referenced to GND...
* additionally there may be input protection against GND..so you loose the protection feature

In case you still use to switch OFF the GND line
* you need to be sure that there is no LOW at the signal lines during OFF (it may kill the device). Use the OE feature of the AHC541

Klaus

 

[sreepss]

Hi,

Hi,

Don't let inputs floating: D7 of U28. --> connect it to GND.

Is T_CS input or output?

***
Why the LED_A connection.

*****

I don't like the GND switching.
* The input signal are referenced to GND...
* additionally there may be input protection against GND..so you loose the protection feature

In case you still use to switch OFF the GND line
* you need to be sure that there is no LOW at the signal lines during OFF (it may kill the device). Use the OE feature of the AHC541

Klaus

> All the inputs of U28, are internally pulled up inside micro controller
> T_CS is the touch controllers chip select input (3.3V Level) so i have connected it through 74AHC
> LCD back light was always ON in that design, But i have modified it to controlled by MC
> I have already changed my ground switching section of LCD, and now its positive side switching with MMBT2222

THANKS FOR THE REPLAY SIR:smile:

 

[KlausST]

Hi,

either you didn´t read my post carefully, or your schematic is wrong.

U28, D7 is definitely unconnected at your schematic, so how can it be "pulled_up" by the microcontroller?

***
T_CS is not connected.

***
High side power switching. Is Better.
But now the datalines should never be HIGH during power LCD_OFF. Else it might hurt your display. --> Use OE function of AHC541.
I recommend to use a zener to prevent LCD_VCC from overvoltage when switched OFF, to maintain overvoltage protection of datalines.
(Not necessary if otherwise overvoltage is prevented)

****

If you have modified your schematic, so please post the updated one. Else we risk confusion, because we speak about different situations.

Klaus

 

[sreepss]

Hi,

either you didn´t read my post carefully, or your schematic is wrong.

U28, D7 is definitely unconnected at your schematic, so how can it be "pulled_up" by the microcontroller?

***
T_CS is not connected.

***
High side power switching. Is Better.
But now the datalines should never be HIGH during power LCD_OFF. Else it might hurt your display. --> Use OE function of AHC541.
I recommend to use a zener to prevent LCD_VCC from overvoltage when switched OFF, to maintain overvoltage protection of datalines.
(Not necessary if otherwise overvoltage is prevented)

****

If you have modified your schematic, so please post the updated one. Else we risk confusion, because we speak about different situations.

Klaus

hello sir

Thanks for your valuable suggestions. I have modified the schematics like this

> I am not using the touch functions so i have not touched the Touch controller section.
> 3.3 V rail is protected with Zener diode