TDA4VM: How to config mcasp data?

eason zhou

Part Number: TDA4VM

Tool/software:

Hi Ti expert

SDK 0902

Now I want to use mcasp to send and recive audio data.

I want to use TDM32 with a slot size of 32.
However, my actual data is effectively 24 bits (signed data).
So how can I use a slot size of 32 to receive and transmit 24-bit signed data?

Best Regards
Eason

2 months ago

0 Jared McArthur 2 months ago

TI__Mastermind 19900 points

Hi Eason,

Slot sizes are 32 bits regardless of the actual data payload.

"In the case of I2S, there are two slots per frame. Each slot consists of 32 bits. Even if the data payload is only 16 bits or 24 bits, it is encapsulated within a 32-bit word."

Section 5.2 of McASP Design Guide - Tips, Tricks, and Practical Examples.

Best,
Jared

0 eason zhou 2 months ago in reply to Jared McArthur

Intellectual 875 points

Hi Jard

Jared McArthur said:
"In the case of I2S, there are two slots per frame. Each slot consists of 32 bits. Even if the data payload is only 16 bits or 24 bits, it is encapsulated within a 32-bit word."

In this case, how to convert the data?

For example, if 32 bits store 24-bit signed data, how are the sign and data bits stored when mcasp parses the data?
How do I receive data using the int32_t type?

Best Regards
Eason

+1 Jared McArthur 2 months ago in reply to eason zhou

TI__Mastermind 19900 points

Hi Eason,

Are you using our MCASP drivers?

PDK driver: https://software-dl.ti.com/jacinto7/esd/processor-sdk-rtos-jacinto7/11_00_00_06/exports/docs/pdk_jacinto_11_00_00_21/docs/userguide/jacinto/modules/mcasp.html

Linux driver: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/sound/soc/ti/davinci-mcasp.c?h=ti-linux-6.12.y

Best,
Jared

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TDA4VM: How to config mcasp data?