`SimpleBacklight.ino` example does not change backlight intensity

[aliphys]

The SimpleBacklight.ino example does not change the intensity of the screen. Other examples in the basic folder run, suggesting that this is not a specific hardware issue. Tested on two different shields and GIGA R1 WiFi boards

[aliphys]

Since the LCD screen of the GIGA Display Shield is such high quality, the bleeding is very faint. This makes it seem as if the backlight intensity does not changes. Furthermore, the example increments the backlight by 1% every 100 milliseconds, which makes it difficult to see the changes with a naked eye.

Arduino_GigaDisplay/examples/backlight/SimpleBacklight/SimpleBacklight.ino

Lines 16 to 20 in de47486

	int i = 0;
	void loop() {
	backlight.set(i++ % 100);
	delay(100);
	}

Given that Users have also reported this issue (e.g. https://arduino.zendesk.com/agent/tickets/294569) we should modify the example so that the change in backlight is visible. This can be done by having the backlight Blink between on and off. Custom values can be left as an exercise to the User.

[aliphys]

Notice that in all set backlight values, the backlight visually looks very similar although the current draw is drastically different.

Backlight (%)	Current (mA)	Picture
0%	110mA
50%	142mA
100%	274mA

[alblib]

I solved the issue. Please look at #37

[alblib]

tick has to be under 50us and use pdm so led driver dont go into digital mode. I worry this can make too much load on the chip. I think this is design flaw of the giga display shield. They should use dedicated pwm pin to control the backlight.