aic33 can not mute

zhenhai yuan

I am having trouble with aic33 codec in DM6437env. That is, after booting DM6437, initializing AIC33, music input, it can play normally.

But the problem is, when I input nothing , I can also hear some noise. Very very low noise, but still can be heard. How can I cancel it and make it absolutely mute ?

LINE1LP, LINE1RP as audio line input.

LEFT_LOP, RIGHT_LOP as audio line output.

As follow schematic.

I have try to configure the registers, but it does not work. Even I set PGA and DAC not route to LEFT_LOP/M and LEFT_LOP/M(configure as follow), I can still hear the noise.

PGA_L not routed to LEFT_LOP/M (Reg81:0x00);

PGA_R not routed to LEFT_LOP/M (Reg84:0x00);

PGA_L not routed to RIGHT_LOP/M (Reg88:0x00);

PGA_R not routed to RIGHT_LOP/M (Reg91:0x00);

DAC_L1 not routed to LEFT_LOP/M (Reg82:0x00);

DAC_R1 not routed to LEFT_LOP/M (Reg85:0x00);

DAC_L1 not routed to RIGHT_LOP/M (Reg89:0x00);

DAC_R1 not routed to RIGHT_LOP/M (Reg92:0x00);

Only when I does not power on LEFT_LOP/M and RIGHT_LOP/M (configure as follow ), that I can not hear the noise. Of cause, at this situation, You can heard nothing when have voice input either。

LEFT_LOP/M is not fully powered up (Reg86:0x00);

RIGHT_LOP/M is not fully powered up (Reg93:0x00);

Thanks in advance.

Best regards,

Yuan

over 13 years ago

0 Converter Apps over 13 years ago

TI__Mastermind 28585 points

Once the DAC is excited with a signal the modulator will continue to run until the DAC is powered down (Register 37, Page 0). The DAC can be powered back up but will not start the modulator until there is a new signal sent to the DAC.

0 zhenhai yuan over 13 years ago in reply to Converter Apps

Prodigy 100 points

Hi,Converter Apps, glad to see your reply.

But I don't quite understand. I use LEFT_LOP and RIGHT_LOP as audio output, but not HPLCOM. Aren't they independent routes ? If not, could you explain more detail ? I try to set Reg37=0x00, But the noise still can be heard ?
Thank you.

0 Converter Apps over 13 years ago in reply to zhenhai yuan

TI__Mastermind 28585 points

LEFT_LOP, RIGHT_LOP, HPLCOM, can all be different paths depending on what settings are used in the output mixers (Registers 46-91). If there is noise with the DAC off, you must have some other source for noise. Are you bypassing one of the inputs to the output?

0 zhenhai yuan over 13 years ago in reply to Converter Apps

Prodigy 100 points

I find the solution. I use HPLOUT ,HPROUT instad of LEFT_LOP, RIGHT_LOP .

Thanks !

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aic33 can not mute