# Control PWM of LCD LED Backlighting
**URL:** https://forum.core-electronics.com.au/t/control-pwm-of-lcd-led-backlighting/7773
**Category:** Uncategorized
**Created:** [21 May 2020 05:52 UTC](https://forum.core-electronics.com.au/t/control-pwm-of-lcd-led-backlighting/7773 "2020-05-21T05:52:49Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Ronald121610](https://forum.core-electronics.com.au/u/Ronald121610)
#### Post date: [21 May 2020 05:52 UTC](https://forum.core-electronics.com.au/t/control-pwm-of-lcd-led-backlighting/7773/1 "2020-05-21T05:52:49Z")
Guys, I purchased this last week:
> **[Waveshare 3.5inch LCD IPS 480x320](https://core-electronics.com.au/waveshare-3-5inch-lcd-ips-480x320.html)**
>
> A perfectly sized IPS panel for a portable Raspberry Pi interface
I opened it up; here are the photos (click on photo so you can see the 2 photos):
[[Album] Lcd  ](https://imgur.com/a/4SwTVcq)
As you can see in the photos, there are 6 LEDs (in parallel) for backlighting. Any idea on which component is driving these LEDs? The chips with partnumbers are for touch panel and audio DAC. If I can find component that provides power to the LEDs, then I can isolate that component and I can inject my own PWM signal (and not via on-screen display).
Help? TIA!
---
### Author:  [@Bryce](https://forum.core-electronics.com.au/u/Bryce)
#### Post date: [21 July 2020 05:59 UTC](https://forum.core-electronics.com.au/t/control-pwm-of-lcd-led-backlighting/7773/2 "2020-07-21T05:59:24Z")
Hey Ronald,
Unfortunately, for these particular Waveshare displays, PWM control of the background is very difficult, as they take power from the 3.3 V and 5 V Rails which are fixed on the Pi. The simplest way to get around this one is to rewire the pinout of the Pi on a breadboard in order to provide a modulating signal to the appropriate pins on the Waveshare display. Please let us know how you go and if there’s anything else that I can do for you.
(Breadboard wiring)
> **[10 Pcs 40 Pin Headers - Straight](https://core-electronics.com.au/10-pcs-40-pin-headers-straight.html)**
>
> This is 40 Pin 2.54 mm Single Row Pin Header Strip. It is great for our FIO and custom PCBs or general custom headers.
> **[Solderless Breadboard - 830 Tie Point (ZY-102)](https://core-electronics.com.au/solderless-breadboard-830-tie-point-zy-102.html)**
>
> If you're prototyping a circuit big or small, then you'll want a quality breadboard, and this one is awesome! It's got dual isolated power rails perfect for complex projects, 830 tie points, and sturdy spring connectors.
> **[Premium Female/Male Extension Jumper Wires - 20 x 12](https://core-electronics.com.au/premium-female-male-extension-jumper-wires-20-x-12.html)**
>
> These Female/Male 'Extension' Jumper Wires are handy for making wire harnesses or jumpering between headers on PCB's. These premium jumper wires are 12
PS. Be sure to check the current and voltage outputs of the GPIO and use a MOSFET or similar device to devise an appropriate way to power the display and provide control signals from the pins.
Bryce
Core Electronics | Support