ILI9341 backlight flickers when using USB power from Laptop I've developed a project using am ILI9341, ESP12F and Arduino. Everything works fine except a very annoying issue. The LCD flickers when I use the laptop's USB. But when I use a USB charger it's much better.
I use https://github.com/Bodmer/TFT_eSPI library for SPI driver and AMS1117 as regulator (with 1uf in the input, and 10uf in output).
I don't think the software has a problem because I don't refresh anything on the display (just draw something in the setup function, not in loop) and also it changes with different power sources. The problem is the backlight.
When I move the USB cable it goes crazier sometimes. I've checked it with many different cables and computers. Is this because of noise or something from the USB port? How can I fix this?
It's very important for me to be able to use the USB port as the power source.
Update
When I'm uploading the code to the ESP8266 (using TXD &amp; RXI), the LCD doesn't flicker event a little bit! And immediately after finishing the upload, the LCD brightness decreases and starts flickering!
The circuit is pretty simple and LCD pins are connected directly as listed here
That happens because not all USB ports can supply more than 500mA of current.
When you use a charger's USB port, it is designed to provide more than 500mA of current(ex. 1-2amps in most chargers). Try using a USB port that can provide more than 500mA of current. Most PCs and Laptops will only supply 500mA at maximum unless specified so. 

More information regarding USB power can be read here on Wikipedia.

Cheers!