Screen Flicker and Audio Noise

[jgrant911]

I'm using the G2 and an Uno to build a system display for my RV which will integrate several functions including: power system monitor, temperature monitor, fresh/waste and propane tank monitor as well as some diagnostic functions. So far I have really enjoyed working with this combo and it has functioned very well for the most part.

Picture of in progress display:


My question is about screen flicker and associated audio noise which seem to me to be abnormally apparent.  I've read your replies regarding  the VOLUME and MUTE functions as well as use of the BACKLIGHT control. With no adjustment of these functions, screen flicker is quite obvious and audio noise is like listening to a waterfall up close. To minimize this I have reduced the backlight to 75 since the panel is in a low light area and I am currently using MUTE to kill the noise since I have no audio output at this point. Works OK for a work-around...

I know others have commented on audio noise but I haven't found complaints about flicker so I wonder if my experience is normal or if I might have a problem with my board/wiring?

[jamesbowman]

Looks great, and it definitely should not flicker!

There are a couple of things to check for flicker.

(1) The main power supply connections draw 0.3 amp, so they need good-sized wires. This current is on the +5V and GND connections:



(2) Make sure that at initialization you are calling GD.begin() with no parameters. Calling GD.begin(0) disables clock tuning at startup, which results in a refresh frequency below 40 Hz.

[jgrant911]

You nailed it!

I had been using a 9V wall wart to power the setup a while back, but at some point I decided to run off just the USB for convenience. Obviously the power requirements of the Uno, G2 and the various sensors attached were enough to make the USB power marginal.

I plugged the 9V supply back in and ran my little test program that puts the G2 backlight thru its complete range. No flicker and acceptable noise levels at full volume on the audio.

Thanks for the help!

Jim