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About AGC Setting Problem in AIC

Liang-Bi Chen
Prodigy 180 points
Other Parts Discussed in Thread: TLV320AIC3204

I have referred SLAA446 Application Report entitled "Using the AGC, DRC and Beep Generator Function in TLV320AIC3204/54/3100/10/11/20/36 Devices", however, the effect of AGC has some problems as follows.

1. We set up Target Level (P0.R86) as a fixed value when input fixed volume, also to modify value of noise threshold (P0.R87) and to read  Gain Applied (P0.R93) which is fixed and no full, in such situation, WHY output volume is also changed?

2. To read (P0, R45, D6), from has sound to no sound, we have read Fg =1 once, Fg=0 after first time. We try this experiment again, thus fg still is "1", For such result, we cannot sure the sound is input, how to make sure have sound IN, also what is purpose of Fg?

3. We can not meet effect of AGC like Figure 1 AGC function when finishing AGC setting.  

4. What is the goal of DRC, We follow thr application note to set up related value for DRC, however, we can not face any effects about DRC.

5. We modified (P0.R83), Sometimes has some effects, but sometimes not any effects. Also, we set "+"db value but the sound is decreased, set "-"db value the sound is increased. Also, we read (P0,R93), however, (P0, R93) value has not any change. For such situation, is it correct working? Could you tell us how to solve above problems, thank you very much!

    

  • 0
    TI__Guru 62076 points

    Which AIC do you use?

    1. If the input signal is below the noise threshold, the AGC won't kick in. If the input signal is constantly above the noise threshold, the AGC will adjust the gain to so that the output of the AGC is at the target level, regardless of the input signal level. Please provide the following:

    * input level [dBFS or Vpp]

    * noise threshold [dB]

    * target level [dB]

    2. P0, R45, D6 on the AIC32x4 and AIC32x6 is a sticky flag, which means it will stay at 1 if the noise threshold has been met until it is read, which will clear it (that's why you read 0 for subsequent reads). If you need immediate results instead, please use R47 instead. The purpose of this flag is to know if the input has crossed the noise threshold level since the last time this register was read.

    3. What doesn't show on your AGC dialog?

    4. The DRC acts as a compressor, meaning that quiet audio data will have higher gain applied than loud audio data. The effect is louder audio without clipping because peaks are automatically attenuated instead of causing hard distortion.

    5. P0 R83 uses 7-bit 2s complement. Please make sure that you use the correct data format. P0 R93 will only change, if the AGC is active and the input signal is above the noise threshold.

  • 0 in reply to Dominik Hartl11
    Prodigy 180 points

    Dear D. Hartl,

    Firstly, thanks for the kindly reply. We have solved some problems, and we adopt TVL320AIC3100.

    However, we also have faced some problems or questions, are arranged as follows.

    1. How to set up the filters? According to our survey for TVL320AIC3100, the filters settings have been provided. However, in the fact, we cannot set up those internal parameters.

    So, could you help me or tell me what are the procedures for setting parameters of the filters?

    2. In addition to AGC method, do you know have the other methods to judge whether Analog inputs? If only AGC judgement method, thus, how to efficient cancellation for feedback noise in NO sounds & higher again conditions?