ST7735 interfacing instructions

[Raja]

After going through the SDK i came across the ST7735 LCD screen example.

On the SDK Page it says example uses the ILI9341 controller, But we can also configure it to use the ST7735 controller. After looking into sdk_config.h it is already enabled as:

// <e> ST7735_ENABLED - st7735 - ST7735R TFT controller
//==========================================================
#ifndef ST7735_ENABLED
#define ST7735_ENABLED 1
#endif

Do i need configure it some where else other than this?

Also wiring is not very clear, can some one point me how wire it with nRF52-DK with ST7735.

link

[Raja]

It is not working anymore. It was working last night now when i switched on the board white screen appears. I initially thought that LCD is broken so tested it on arduino with adafruit library that worked screen started working after i pressed reset button on arduino nano. 

Then i plugged back lcd for nRF52-DK hoping it will work but it did not work. I pressed reset button even reprogrammed firmware few times but it does not work anymore. It prints the log message on putty but LCD does not work with nRF52-DK now.

Where as when i plug it on arduino LCD works fine after pressing reset button. Not sure what has gone wrong with it now.

(Also i have found when i just connect scl and sda to LCD from arduino it turns on the white screen. But this does not happen on nRF52-DK.)

[Edvin]

Hello,

Not sure, but it might be that it can't deliver enough power if you are using a USB hub. Can you try to connect the USB cable that your DK is connected to directly into the computer?

BR,

Edvin

[Raja]

Hi Edwin, i have checked vcc power is sufficient. Also it is not connected to hub but directly on machine. I am really puzzled what is wrong it was working one day next day it stopped working without any change.

Are we sure RESET pin needs to be connected to VDD? 

I have purchased few other LCD none of them works now. Do i need to power up the scl, sda, dc, cs pin to 5 v like arduino?

What LCD was used in the GFX example at nordic? I can buy and try that.

[Edvin]

You don't have a logic analyzer, like the saleae logic analyzer, by chance? It would be interresting to see if there are any difference between SDA (MOSI) on the Arduino and the nRF. 

 

regarding the RESET, I am not sure how it behaves. You have to check the datasheet of your screen whether it needs to be grounded or connected to VDD. I believe VDD is typical for these kind of pins. That means that when the pin gets a GND pulse, it will reset.

 

As you can see here, it uses the ILI9341.

 

Are you sure that there were no changes between the time that it was working and now? Can you try to unzip the SDK again and try with an unmodified version of the example? (only with the changes described to change to the ST LCD screen).

 

BR,

Edvin

[Raja]

Thanks for advice I have purchased it now, will receive it soon. Will test it and send the difference here.