TAS5828M: Stereo Volume settings

Hendrik Marske

Prodigy 10 points

Part Number: TAS5828M

Tool/software:

Hi,

Im trying to configure the volume of each channel of the TAS5828m indepently.

I understand that there is only one setting for both channels on book 0, page 0 as documented in the datasheet.

Also from the datasheet there is some information about configuring the volume via "DSP Volume" on book 0x78, Page 0x2A, Registers 0x24, 0x28, 0x30.

Is there any documentation of this available? What do i need to set?

Kind regards

Hendrik

11 months ago

0 Sydney Northcutt 11 months ago

TI__Mastermind 23260 points

Hello,

You can refer to the following process flow document for TAS5828M which has a Volume section: https://www.ti.com/lit/ug/sluudb4/sluudb4.pdf?ts=1753287695235&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTAS5830

Overall I recommend our GUI PPC3 to set up device registers as it is much easier than doing it manually.

Regards,
Sydney Northcutt

0 Hendrik Marske 11 months ago in reply to Sydney Northcutt

Prodigy 10 points

Ok so i was able to understand that its on book 0x8c page 0x06 registers 0x64 (left) and 0x68 (right).

According to the datasheet its the "volume coefficient". What exactly does that mean?
I also tried to understand what the 9.23 format exactly means. It represents the value as an fixed-point value using 9 Bits (-1 signed bit) for the decimal part and the remaining 23 bits for the fractional part.

I therefor calculate the floating point value of a given value as follows:
float f = fixed_point / (2^23)

This checks out as the default value of 0x00800000 calculates to 1.0

But when i try to log the i2c-communication using the ppc3 i see the Values being set for:
0dB -> 0x00 80 00 00 (as epected as its the default value)
1dB -> 0x00 8f 9e 4d => when i recalulate it with the formula above i get 1,12201....
-1dB -> 0x00 72 14 83 => when i recalculate it with the formula above i get 0,89125....

So how can i calucate each step in full dB?

Are my other findings correct?

0 Sydney Northcutt 11 months ago in reply to Hendrik Marske

TI__Mastermind 23260 points

Hello,

Typically DSP volume is set one time for the system which we recommend configuring with PPC3 due to the calculations. We just refer to registers in the DSP as coefficients. In the end equipment we recommend controlling the volume with the DAC volume register on page 0.

Are you asking for the calculations so you can control the volume with the driver in the end system?

Regards,
Sydney Northcutt

0 Hendrik Marske 11 months ago in reply to Sydney Northcutt

Prodigy 10 points

as far as i can tell the DAC register only controls the volume for both channels at the same time.

I am working on an application where i am trying to create some kind of magnetic field around a wire buried underground.
I want to control both channels independently and therefor need to control the "volume" of each channel independently.
I also need to control this on runtime.

I there is some (maybe undocumented) register on book 0 page 0 i would be very grateful if you could point me in the right direction.

I understand that this might not be the typical application but all i really need is a way to control the voulme of each channel independetly on runtime.