TAS2764EVM: Slope calculation

Hi Vineeth,

Regarding LIM_SLOPE, you should notice this is a 32-bit coefficient, based on this you cannot set such a high slope as 18 as you would need at least 33-bits. As an example, default value is 0x10000000 corresponding to 1V/V slope.
From PPC3, you can uncheck the "Limiter Dynamic Headroom Enable" to access the Threshold, Inflection and Slope. These are alternative modes, you can use either Dynamic or set each parameter individually.

LIM_SLOPE 1 - 4 are 4 registers of 8-bits each, all are used for slope configuration as this is a 32-bit coefficient.

Can you elaborate on you questions about SDL Threshold? I'm not clear on this one.

Similar equations are provided for thermal foldback parameters on TF_SLOPE, TF_TEMP_TH and TF_MAX_ATTN. Attenuation is applied logarithmically for listening purposes.

The main parameters on BOP are threshold and max attenuation. Threshold sets at which voltage (horizontal axis) the BOP triggers, and the vertical value to the left of that threshold is the max attenuation. It applies similarly for all 4 levels so you can have stepped attenuation depending on the VBAT level.

PPC3 may be writing to both devices on the EVM, the same settings for each one. You may use "Export All Registers" option from the main dialog on the top-left corner. It's still configuring all registers but should be less commands. Otherwise you'll have to check which registers can remain in default settings and remove from the sequence.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Ivan Salazar said:

Can you elaborate on you questions about SDL Threshold? I'm not clear on this one.

I wanted to know how to calculate the peak output from the graph for a specified headroom. It was also shown that there is an offset of 0.75% headroom added to dynamic headroom. I didn't got this point.

I really appreciate if you can help me with one other problem also. I wanted to test the IV sense feature of the TAS2764 using I2S without using PPC3. Is there is any sample code for that? Can I use the EVM and CCS to do the same. If I am using the USB connection mode instead of JTAG how can I write the code for the same. If you can provide me with some sample code it would be really helpful. Although I found one I2S.h file in TI archive still I don't know how to use it and I am using USB connection at the same time?

Regards,

Vineeth

Hi Vineeth,

I'll check about the 0.75% headroom and get back with some feedback next week.

What test do you need to do with IV sense? Are you trying to initialize TAS2764 so that it sends I and V sense data back through I2S, then record on the PC like if EVM was a sound card? Are you able to do this using PPC3 already but want to test this with a different controller other than the xMOS onboard? 

You can write the initialization over I2C to the device using either PPC3, or any external controller connected to J28. If using an external controller, you can get the required register settings from "Export All Registers" as mentioned before, or you can use the I2C monitor on PPC3 to record all the settings you perform on the GUI (this option would create a larger command list).

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Thank you for your response.

My idea is to read the I2S data in a bare metal environment from the EVM.

Ivan Salazar said:

Are you trying to initialize TAS2764 so that it sends I and V sense data back through I2S, then record on the PC like if EVM was a sound card?

Yes I want to initialize the TAS2764 so that it sends I and V data back through I2S. May be I can use PPC3 for initialization, but I want to read the I2S data from the board in a bare metal environment. If I want to do the same since the board is connected through USB which uses XMOS on board, I need to write code for both XMOS and I2S using TAS2764 right? As of now I don't have any sample code for either of this that's  why I asked you for a sample code.

My another  thought was I will write a code to both initialize (I2C) and read the data from the EVM via I2S. But Still the board is communicating through USB so, I don't know how to address the XMOS part.

Regards,

Vineeth

Hi Vineeth,

For testing purposes I would suggest to use J28 to connect bare metal I2S host, while using PPC3->USB->xMOS for I2C control. The procedure would be as follows:

• Set J31 jumper to "J28(EXT)", keep J29 on "USB(INT)"
• Connect external I2S host to J28
• Execute PPC3 and open TAS2764 plugin
• Connect EVM to USB and Power, then connect to PPC3
• Navigate to Device Control panel, then TDM Transmitter and click on "Configure Slots"
• Click on "+" to add I-sense and V-sense to the output stream, then click on "Apply"
• Make sure external I2S host is up and running clocks to EVM J28 connector
• Click on "Power Up" button, at this moment the device should be fully initialized and sending back IV data through i2S

The overall connection would be like this:

Best regards,
-Ivan Salazar
Applications Engineer

Hi Ivan,

Thank you for your response. I will try this. May I ask is there is any sample I2S code available ?

Regards,

Vineeth

Hi Vineeth,

I'll share an example setup/results later today or tomorrow morning.

Best regards,
-Ivan Salazar
Applications Engineer

Hi Vineeth,

Attached is a configuration script that enables IV-sense feedback, you can follow the same hardware setup I mentioned a couple comments above:

• Set J31 jumper to "J28(EXT)", keep J29 on "USB(INT)"
• Connect external I2S host to J28
• Execute PPC3 and open TAS2764 plugin
• Connect EVM to USB and Power, then connect to PPC3
• Enable the external I2S host, make sure clocks are fed to the EVM
• Click on I2C on the bottom of PPC3 to open the monitor, then copy the script and click on Execute
• At this moment the device should be enabled, you should get I-sense on slot 0 (left) and V-sense on slot 1 (right)

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Best regards,
-Ivan Salazar
Applications Engineer