BMPDraw() not working when MOSI and CLK pins are given in the constructor. (ScreenTFT_ILI9340-ILI9341 sample)

[profjmer]

From sample: ScreenTFT_ILI9340-ILI9341, with the same board, same chip, but using different constructors, BMPDraw() do not work with constructor using mosi and clk pins.

#define ili9341_DC 2
#define ili9341_CS 15
#define ili9341_RST -1
#define ili9341_MOSI 13
#define ili9341_MISO -1
#define ili9341_CLK 14

namespace
{
Adafruit_ILI9341 tft = Adafruit_ILI9341(ili9341_CS, ili9341_DC, ili9341_MOSI, ili9341_CLK,ili9341_RST, ili9341_MISO);
//Adafruit_ILI9341 tft = Adafruit_ILI9341(ili9341_CS, ili9341_DC);

if I use Adafruit_ILI9341 tft = Adafruit_ILI9341(ili9341_CS, ili9341_DC); BMPDraw() works.
if I use Adafruit_ILI9341 tft = Adafruit_ILI9341(ili9341_CS, ili9341_DC, ili9341_MOSI, ili9341_CLK,ili9341_RST, ili9341_MISO); Screen text and gui work but BMPDraw() do not show sming.bmp.

[mikee47]

I've had a dig about in the Arduino library code, and it looks like this is related to how the various constructors work.

In the default case:

Adafruit_ILI9341 tft(ili9341_CS, ili9341_DC);

The library takes a reference to the global SPI instance, which is the standard hardware SPI driver.

With your custom constructor:

Adafruit_ILI9341 tft(ili9341_CS, ili9341_DC, ili9341_MOSI, ili9341_CLK,ili9341_RST, ili9341_MISO);

The library switches to its internal software SPI driver.

Also the BMPDraw function is not a standard part of the Arduino_GFX library: it was added in #1722 because the code was used all over the place. As such it hasn't been tested with the software SPI mode of the Arduino_TFT library.

The solution is similar to #2926 therefore to retain the standard constructor and set the pins on the SPI object instead:

Adafruit_ILI9341 tft(ili9341_CS, ili9341_DC);

void init()
{
  SPI.setup(SpiBus::DEFAULT, {
    .sck = ili9341_CLK,
    .miso = ili9341_MISO,
    .mosi = ili9341_MOSI,
  });
}