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• TI Thinks Resolved

Hello
AGC configuration to reduce the noise floor and people get away from or close to the microphone can get the best sound, the current PGA is controlled by the keys and found AGC enabled PGA control is not obvious?, the sampling rate fs = 48k, AGC related register configuration as follows :

ADC3101_Write(0x56,0x80);//r86 Left AGC enabled, target level = –5.5 dB
ADC3101_Write(0x58,0x28);//r88 Left AGC maximum gain = 20 dB
ADC3101_Write(0x59,0x08);//r89 attack time=3×(32/fS), Multiply = 1
ADC3101_Write(0x5a,0x08);//r90 decay time =3×(512/fS),Multiply = 1
ADC3101_Write(0x5b,0x01);//r91 noise debounce = 4/fS,signal debounce = 4/fS

According to a given sampling rate, the value of the above register need to be configured into what, in order to get the best sound it?

• The register has now been configured as follows:

ADC3101_Write(0x56,0x80);//r86 Left AGC enabled, target level = –5 dB
ADC3101_Write(0x58,0x28);//r88 Left PGA maximum gain = 20 dB
ADC3101_Write(0x59,0x10);//r89 attack time=3×(32/fS), Multiply = 1
ADC3101_Write(0x5a,0x00);//r90 decay time =3×(512/fS),Multiply = 1

The noise problem seems to be better than before, but the current sound distortion, there is the volume control is invalid, try to control the Table 74. Page 0 / Register 88: Left AGC Maximum Gain This register to control the sound, but out of this The sound quality is particularly poor, but also lost the original function of AGC, may I modify which registers can be achieved, in the case of the volume control can also maintain good sound quality?

• Volume control I achieved through the PGA:

uint8_t Left_Analog_PGA_Init[10] = {0x10,0x00,0x0a,0x14,0x1e,0x28,0x32,0x3c,0x46,0x50};//page 1  register 59

After AGC is enabled, the gain read from the PGA last read through Page 0 / Register 93: Left AGC Gain Applied is the value set by the AGC Maximum Gain

Hi, Char,

For tuning of the AGC, I would recommend you to use the GUI of the 'ADC3101, the AGC tool is quite helpful and easy to use. Also, to fine tune the signal to avoid noise distortion, you shall play with the timing constants. In general, the default values are a good starting point.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

• In reply to Diego Melendez:

Hello
Will you say that the GUI is purepath studio (gde)? If you want to achieve the input analog signals, output I2S, volume control and AGC, which components need to drag it?

Hi, Char,

I was actually referring to the AGC tool available in the 'ADC3101 Control Software, not PurePath Studio. However, PurePath Studio also has a tool to configure the AGC. Please take  a look to the Control software tool that is available in the 'ADC3101EVM.

Best Regards,

-Diego Meléndez López
Audio Applications Engineer

• In reply to Diego Melendez:

Hello there:
Are you talking about this ADC3101_CS_v1_2_0? This software needs to cooperate with TLV320ADC3101 evaluation module (EVM) and USB motherboard to use right? We currently do not have this development board, through the I2C interface of other microcontrollers to configure the registers inside the ADC, the problem of noise can be solved by hardware, but now the most crucial issue is to enable the volume after AGC can not control; excuse me this question how should I solve this?

Hi, Char,

Sorry for the late reply. yes, the CS software requires the EVM to generate the required configuration script. For PurePath Studio, there is an example of an AGC implementation for the ADC section of the AIC3254 codec, which you can use as reference for the implementation on the 'ADC3101. the example is located in: