PUREPATH-CMBEVM: PSIA clocking

Alex Stahl

Part Number: PUREPATH-CMBEVM
Other Parts Discussed in Thread: TAS5766MRMTEVM

Hello,

I am planning to try the PPCMBEVM (Rev. F or G) with an external I2S source for a test. I've seen the notes at https://e2e.ti.com/support/amplifiers/audio_amplifiers/w/design_notes/2768.how-to-configure-ppcmb-for-external-audio-interfaces, studied the schematic, and have built custom process flows for the AIC3262 for previous tests.

I have a few questions. Is the external PSIA a clock master by default? If not, can it be configured as such?

Thanks in advance for any head-start time-savers on this issue.

-Alex Stahl

over 8 years ago

0 Shawn Zheng over 8 years ago

TI__Mastermind 24835 points

Hi Alex,

Could you please let me know which digital input class-d device are you evaluating? Basically TAS57xx works as an I2S slave device, and it accepts MCLK, SCLK and LRCLK. Please let us know if you have more question.

Best regards,

Shawn Zheng

0 Alex Stahl over 8 years ago in reply to Shawn Zheng

Intellectual 280 points

Hi Shawn,

Thanks for your reply. We’re testing the 5766 and 5760 amplifiers. Sounds like we should be able to make this work.

Thanks again!

Alex Stahl

0 Shawn Zheng over 8 years ago in reply to Alex Stahl

TI__Mastermind 24835 points

Hi Alex,
I think it should work. Andy is the expert in these two devices, and he will give more detailed explanation on this later.
Best regards,
Shawn Zheng

0 Andy Liu (BMS) over 8 years ago in reply to Alex Stahl

TI__Guru 52115 points

Hi Alex,

To enable the external I2S (PSIA) on PPCMB, run the script below in the PPC3 GUI.

# Change to GPIO mode
i gpio
# Set bank 0
w 99 04 01
# Clear bits (command 01) with mask 20 - clears P1.5 of Bank 0
w 99 01 20

# Go back to I2C mode
i i2cfast
# Set pins 21-24 as outputs
w 44 0E 0F
# Set pin 23 high (MCLK-MUX = PSIA)
w 44 06 7F

Andy

0 Shawn Zheng over 8 years ago in reply to Andy Liu (BMS)

TI__Mastermind 24835 points

Hi Alex,
Could you please help to close this question if it's answered? Thank you!

0 Alex Stahl over 8 years ago in reply to Shawn Zheng

Intellectual 280 points

Hi Shawn and Andy,

Thanks very much for your help. My next step is to modify the self-boot demo to support PSIA input, I think I see what needs to be done for that.

Thanks again!

0 Alex Stahl over 8 years ago in reply to Alex Stahl

Intellectual 280 points

Oops, I have a followup question on this topic. My external I2S source provides a 24.576Mhz MCLK. By default, the PPCMBEVM and TAS5766MRMTEVM appears to run at 1/2 this frequency-- 12.288 Mhz. I'm pretty sure I can find the register to change the MCLK/SCLK ratio in the 5766 (time-saving hints welcome :), but my question is, do I need to change the MCLK rate for any other components on the CMBEVM? I think the answer is no but I just wanted to check in first. Thanks!

0 Alex Stahl over 8 years ago in reply to Alex Stahl

Intellectual 280 points

By the way, if it's better to start a new thread rather than reply to a resolved topic, I'm happy to do that.

0 Shawn Zheng over 8 years ago in reply to Alex Stahl

TI__Mastermind 24835 points

Hi Alex,
This is quesion has been already closed, please help to create another new post for the other question. Thank you!

Audio

Audio forum

PUREPATH-CMBEVM: PSIA clocking