ILI9488 4-Wire SPI library

Other Hardware Displays
1

Hi.

I have a 3.5'' TFT display that I got from aliexpress: https://goo.gl/DvX99f
I am trying to hook it up with my Arduino Mega 2560 using 4 Wire SPI. So far it seems to work with
jaretburkett's git library( GitHub - jaretburkett/ILI9488: Arduino Library for the ILI9488 TFT controller for 4 wire SPI ). The problem is that it is way too slow. A fillScreen takes almost 10 seconds which is unacceptable for my project.

I also tried to modify Adafruit_ILI9341 library myself but since I am fairly new to this, no luck so far. My best result on this one was to get something on one part of the screen and with totally wrong colors.

I made sure to use 3.3v logic level shifters from the Arduino. So far my connections look like this:

ILI9488 Mega

GND ---> GND
VCC ---> 3.3V
LED ---> 3.3V
CS ---> D10
D/C ---> D9
SCK ---> D52
MOSI ---> D51

I wonder if someone can help me find a better library to use. Thanks.

2

The ILI9488 is inherently slower with SPI interface. Whereas you can write a 16-bit (565) pixel in parallel mode, you have to use 3 bytes for a (666) pixel in SPI mode.

The ILI9341 can be configured for 2 bytes (565) or 3 byte (666) in SPI mode. The ILI9481 / ILI9486 / ILI9488 can only use (666) mode.

Using DMA with SPI mode is very attractive for (565) pixels. Not so easy for (666) pixels.
Of course the Mega2560 does not have DMA.

Incidentally, it looks as if the full range of 2.2" to 3.5" Red displays have got switchable LED backlights.
The older TJTCM 2.2" to 2.8" boards do not have transistor switch for the LED.

David.