PCM1789 no signal at outputs!

Roman Grinev

Other Parts Discussed in Thread: PCM1789

I'm using PCM1789 in my design with PIC32. I've initialized I2S bus according to PCM1789 datasheet, format: I2S 16bit, (SCK=12.288000MHz, BCK=3.0MHz, LRCK=48KHz). It's been checked with my oscilloscope. When I trying to out test samples over I2S, at the DAC output: constant voltage equal to 0.5xVCC1. I've no idea what to do. Can anyone explain me what's wrong?

over 8 years ago

0 Luis Fernando Rodriguez S. over 8 years ago

TI__Guru* 84915 points

Hello, Roman,

Welcome to E2E and thank you for your interest in our products!

Could you provide your register configuration in order to have a better approach to this issue?

Thank you!

Best regards,
Luis Fernando Rodríguez S.

0 Roman Grinev over 8 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 70 points

I tried to left it unitialized (default configuration), and now I tried to initialize via I2C (20pin tied to GND, 21/22-SDA/SCL, 0x98 i2c address) but it gives same result: no output - just 0.5xVCC.
i2c config:
i2c_write(16, 0xC0);
i2c_write(17, 1<<7 || 1);
i2c_write(18, 0);
i2c_write(19, 0);
i2c_write(20, 3);
i2c_write(22, 0x00);
i2c_write(24, 0xFF);
i2c_write(25, 0xFF);
btw, all I2C transfers ACKed by PCM1789.

0 Roman Grinev over 8 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 70 points

Checked bus signals with logic analyzer, MCLK (SCK, REFCLK) looks unstable, this could cause the problem? MCLK it's a REFCLKO1 of PIC32MZ.

0 Roman Grinev over 8 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 70 points

Any idea?

0 Luis Fernando Rodriguez S. over 8 years ago in reply to Roman Grinev

TI__Guru* 84915 points

Hi, Roman,

I would recommend to modify register 20. This register seems to be configured enable mute. Could you configure it to disable the channels mute?

Thank you.

Best regards,
Luis Fernando Rodríguez S.

0 Roman Grinev over 8 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 70 points

Thank you, I tested this setting with 0x00 and 0x03 - but unfortunately, at outputs still 0.5xVCC and no test samples. Maybe the silicon is an issue? Isn't it? So, maybe unstable Master clock frequency can be affected on the DAC? I used high-speed RC generator on the input of the PLL and as result Master clock is floating.

0 Luis Fernando Rodriguez S. over 8 years ago in reply to Roman Grinev

TI__Guru* 84915 points

Hi, Roman,

I verified the register configuration and it seems to be in order. Could you verify that all clock settings? I think that this issue could be related with unstable Master Clock as you mentioned.

Best regards,
Luis Fernando Rodríguez S.

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PCM1789 no signal at outputs!