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buzzing on PWM line

 
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neochrome32



Joined: 09 Jun 2013
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buzzing on PWM line
PostPosted: Sat Aug 23, 2014 9:09 am     Reply with quote
CCS C 4.130

Sorry to be a little vague here, I am trying to get audio out on a PWM pin on dsPIC33EP 512 GP 806
i am using a SSD1963 800x480 LCD, which is working nicely.

there is noise from the inverter the LCD (which im aware of)

HOWEVER im hearing the noise along the PWM line D7 at around 15Khz, i've put a decoupling cap on the LCD power pins, it reduced a bit but not alot!

the power supply is the pic kit 3 (development, not tried a battery yet)

i've supplied the circuit diagram, the values on it are educated guesses not yet sat down to calculate properly.

[img]www.electronscape.co.uk/help_v1.png[/img]

what am i missing? or have i totally missed the point of the caps on the power supply regs?


Thanks guys
PCM programmer



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Posts: 21708

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PostPosted: Sat Aug 23, 2014 11:40 am     Reply with quote
Search for this with Google:
Quote:
pwm induced noise in audio circuit

Example of hit:
http://forum.arduino.cc/index.php?topic=13160.0;wap2
neochrome32



Joined: 09 Jun 2013
Posts: 153

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PostPosted: Sat Aug 23, 2014 12:29 pm     Reply with quote
-_- thought i had looked! thanks PCM Programmer
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