TAS2557EVM: Queries

Hi Shinu,

I'll add some comments on each question below:

1. Can I use EQ and other tools without characterizing the speaker?
   1. You can. If you're not characterizing the speaker, I assume you don't need the speaker protection, in that case you can set the protection limits for excursion (Xmax) and temperature (Tmax) to the maximum values (10mm and 1000degC respectively). Then you can configure EQ and other features normally.
2. Why am I unable to see data in the voltmeter or energy meter?
   1. Can you elaborate? What or where are these meters?
3. How can I increase the volume of the speaker?
   1. If you're testing with the default settings in Tuning mode, the speaker protection may be unnecessarily limiting the output. As mentioned in (1) above, you can relax the protection limits, and this should allow the amplifier to reach higher power levels.
4. There seems to be no difference in sound output when I change the setting to “Right,” “Left,” or “Right+Left/2” in PPC3.
   1. The difference here would also depend on the audio file being used for testing. The audio file should have different data for Left and Right channels.
5. Compression in DRC is not making any difference in sound.
   1. How are you testing the DRC effects? If you're setting the DRC for compression on the higher amplitude region, you should see the different input levels getting closer to each other, similar to this plot: TAS2563 Tuning Guide (Rev. A)

Best regards,
-Ivan Salazar
Applications Engineer

I have kept the protection limits as suggested, is there any other way I can increase the volume of the speaker. 

Hi Sakshi,

It's not clear to me if the amplifier is limiting the power or the maximum power from the amplifier is not enough. Can you try configuring the device in ROM mode to remove all limitations and see if the volume is OK for you? To do this you use PPC3 -> TAS2557 app -> Test and Measurement -> click on either ROM mode 1 or 2:

Best regards,
-Ivan Salazar
Applications Engineer

Thankyou Ivan, I am able to increase the volume by changing the protection limits.
Can you tell me more about ROM modes, how is ROM1 different from ROM 2. 

Thank you for your response. 
I am new to audio engineering, Till now I have been playing audio by uploading it in PPC3, now I want to give input directly to I2S pins of TAS2557, can I play audio like this  ?  

Thankyou I am yet to do the I2S connection will try this and get back to you. 
Also I measured current at speaker output by connecting external supply at VBAT1(J2) but current through speaker output is very low. What is limiting the current? Why am I not getting the optimum power?

Hi Sakshi,

Can you comment if you're using tuning mode or ROM mode?
(going back to my comment from a month ago: (+) TAS2557EVM: Queries - Audio forum - Audio - TI E2E support forums)

Best regards,
-Ivan Salazar
Applications Engineer

Hi I am using Tuning mode since I want to integrate some of the filters in the section "tuning and audio processing", Once I change the mode to ROM1or ROM 2  the audio quality is not how it is in tuning mode. 

Hi Sakshi, 

Responses will be slightly delayed due to work related travel. Thank you for your patience!

Regards,
Sydney Northcutt

Hi Sakshi,

Understood, have you changed the protection limits as I suggested in my first reply to this thread?:

TAS2557EVM: Queries - Audio forum - Audio - TI E2E support forums

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan, so there is some issues with the board, looks like we have short circuited some IC, we are waiting for another board. Also I have changed the protection limit as suggested earlier, that did improve the sound levels, but its lower than the db value we require. Is there anything else which might be limiting the power?

Hi Sakshi,

Please share captures of the output waveforms from the speaker, using a low-pass filter would help checking if there's any clipping or similar issue. How much power are you getting at the load and how much do you require?

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan, 

Thankyou for your response, As I mentioned earlier I am waiting for the board, once I get the board I will perform the above test and send the captures. 

Hi Ivan,

1. You are asking to implement Low pass filter in the console?  
2. I wanted to play real time audio by capturing analog signal from my device, I am connecting raspberry pi 5 with EVM, for this I will have to connect I2C and I2S.
   • Can I connect I2C using USB and I2S externally?
   • If I connect both externally, I will have to remove J27 right? Any other changes on the board?

Hi Sakshi,

1. I mean using either RC or LC low-pass filter so that the Class-D signal looks analog-like instead of a switching square wave.
2. You can use I2C from USB-GUI and external I2S. For external I2S you can refer to user's guide page 10: https://www.ti.com/lit/ug/slou461/slou461.pdf#page=10
   1. If you want to test with external I2C as well, you should remove J19 and J20, and use the middle pin (pin 2) to connect with the amplifier.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan, 

My EVM is not enumerating as a USB Audio device. The blue led light is not on, Device manager recognize the evm as unknown device. What could be wrong with the EVM ?

Hi Sakshi,

Have you used this EVM successfully before?
Please share a picture of the board, we should check your jumper settings and how you're powering it.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan, yes I was using it normally and next day I realised that its not connecting to my Laptop. 
I have checked all of the power (5V,3.3V, 1.8V), They are all good. 

Hi Sakshi,

I assume you also tried different USB cable, different port and different PC?

It's unclear what could be wrong, perhaps the board got damaged?

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,
Yes I have tried different port,cable and PC. This is a fairly new board, and we have only used it to connect to an external speaker and play audio using PPC3. I initially suspected an EEPROM reset issue and attempted the steps outlined in this [link], but the board still does not seem to connect.

Hi Sakshi,

Do you see anything changing at all on Device Manager when connecting the board to USB?
I would also check signals around the board, like I2C and I2S with a scope and see if these signals may be working or not.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

I see the USB as DFUSB, no other changes, Also I can see I2S clock signals and both the I2C pins are high. 

Hi Sakshi,

With the EVM unpowered and disconnected, can you check the impedance between SDA and SCL pins? Perhaps there's something on the board shorting these pins together, which causes the USB controller to be detected as DFUSB always.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan, 
SDA - 12.26k and SCL -12.22k, I can see I2C clock signals when I press reset. 

Hi Sakshi,

When you follow the instructions to re-program the firmware, make sure to short the SDA and SCL lines, wait for few seconds, then remove the short and then proceed with the rest of the steps.

Other than that, I don't know what else to suggest.

Best regards,
-Ivan Salazar
Applications Engineer