According to aic3204 data sheet 184.108.40.206. when choose PTM_R2 with common mode 0.9v, max allowed input is -12db relative to 500mv. My question is that an input 125.6mvRMS(-12dB to 500mv) will result in an ADC digtial full scale, is that right?
A -12dB maximum allowed input means that the ADC maximum will be -12dB relative to full-scale. So for 0.9VCM, this means a -12dB below 500mVrms (about 125mVrms) will produce a -12dBFS digital output. Anything above will be distorted. So to achieve 0dBFS, you would amplify the signal using the ADC digital gain by 12dB. The SNR number in the PTM tables takes this into account.
Thank you, I got the idea.
I have another question about DRC Gain. "When the DRC is enabled,the applied gain is a function of the Digital Volume Control register setting and the output of the DRC.", this is from 3204 data sheet. Suppose the Digital Volume Control register setting is 10dB, the applied gain will be more or less than 10dB, according to DRC filter output high or low, is it correct? or it works in other way?
The DRC block does compression and make-up gain as well. With 0dB gain, DRC does not compress. At 10dB digital gain, a 0dBFS signal input will be decreased to around 0dBFS (i.e. no gain). Low level signals will be amplified by 10dB and signals above a certain threshold will have a gain between 10dB to 0dB depending on the compression ratio.
The HPF filter is fed to both the output and DRC control input. The LPF filter is fed only to the DRC control input and is used for energy estimation.
I use PPS to program aic3254. I know how to access calculation result in data memory, where can I find information of data address in PPS?
If TI provide MiniDsp assembly language tools to user?
I use PPS to program aic3254. I want to know how to access calculation result in data memory, where can I find information of data address in PPS?
sorry, I lost word "want to " in previous message.
Hello Bo Li,
You can use the I2C Memory Tool to view a Data value during run time. You can launch this tool in GDE by choosing Tools->I2C Memory Tool.
You can view the data address by looking at the generated Source code. Click on View->Source code, this will contain information on the addressed of Data variables.
Once you have the address of the desired Data variable, using I2C memory tool you can "Peek" the value by specifying its address, then click swap and click Peek. You can similarly "Poke" write a specified value to a Data variable during run time. Note that you have to choose the right miniDSP associated with the Data variable.
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