GD77 transmitted audio has interferences

n8qq
Posts: 2
Joined: Thu Apr 02, 2020 7:53 pm

Re: GD77 transmitted audio has interferences

Post by n8qq » Fri Apr 03, 2020 4:28 am

I'm finding the noise isn't noticeable when keeping the brightness at 30%, and that's even a little brighter than I keep other rigs with similar monochrome displays -- like the ID-51A and FT2DR. So, no worries here.

oh4va
Posts: 25
Joined: Sat Mar 07, 2020 7:14 am

Re: GD77 transmitted audio has interferences

Post by oh4va » Fri Apr 03, 2020 4:58 am

VK3KYY wrote:
Thu Apr 02, 2020 9:46 pm
The backlight PWM noise problem has been logged as an issue.

https://github.com/rogerclarkmelbourne/ ... issues/521

I don't personally have time to fix it.
Roger, don't worry. We try to fix it.

I installed the IDE yesterday and managed build the firmware. I have some ideas which need more investigation. I am not a professional in embedded systems but I have done something, like this https://github.com/oh4va/hybrid-repeater. I have written the code for AtTiny85 which controls a bilateral audio switch 4066.

BTW, is there any way to debug the code while it is running in the radio?

73 de VA

VK3KYY
Posts: 7478
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: GD77 transmitted audio has interferences

Post by VK3KYY » Fri Apr 03, 2020 5:06 am

If its the PWM, you'll need to modify the code so that if the brightness is 100% (or 0%) it does not use the PWM at all.

Currently there is a preprocessor define to enable the PWM, If you remove it and recompile it switches to non PWM, but this has not been tested for ages, so it probably does not work correctly.

Your solution would need to dynamically switch between PWM and GPIO mode.

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