TLV320ADC6140: I2S spikes of 0x800000 and 0x7FFFFF

Benno Geels

Part Number: TLV320ADC6140

I have an application where the TLV320ADC talks to a ADAU1710 by I2C, I used the register values shown below (the rest of the registers is factory default)

0x02 0x81
0x07 0x60
0x08 0xA0
0x08 0x20
0x0C 0x20
0x0D 0x40
0x0E 0x60
0x13 0x01
0x16 0x00
0x21 0x31
0x74 0xF0
0x75 0xF4

The input of the ADC short with a resistor of 5k6 and nothing else connected. Measured DC voltage on both inputs is 1.412V DC, de values on the I2S bus show normal noise values as to be expected.

several times a second there is a value of 0x800000 or 0x7FFFFF on the I2S bus. Also is there some sort of RC curve after the spike.

I have put the I2S values in a excel sheet and a pico scope capture of the events.

Benno

over 5 years ago

0 Steve-Wilson over 5 years ago

TI__Mastermind 30220 points

Hello Benno,

are the ADC inputs AC coupled with a 5K6 resistor shorting them?

What is your desired sampling frequency?

The I2C transaction below is a little confusing. it looks like you are changing the MCLK frequency for master mode... but you aren't in master mode.

0x13 0x01

and otherwise your setup looks good.

I see you are using both ASI buses. Are you seeing this problem on both buses? can you capture the FSYNC, BCLK and DOUT?

best regards,

-Steve Wilson

0 Benno Geels over 5 years ago in reply to Steve-Wilson

Prodigy 60 points

Yes the ADC inputs are AC coupled

Sampling is 48kHz and in slave mode.

For the 0x13 I was not sure but it would not hurt to set it to the right division value.

I am seeing this on both ASI busses (bus 2 more often than bus 1)

Checked VREF AREG DREG AVDD MICBIAS(MPWR1) and IOVDD for spikes or dips but these remain complete flat at their documented voltage levels.

The capture of the digital signals (including decoding is in the capture analog + digital file)

you can view this with pico software

0 Benno Geels over 5 years ago in reply to Benno Geels

Prodigy 60 points

Digital data of a 0x800000 event on DINP2 (TLV320ADC GPIO1)

Dout = DSP output

DINP1 = TLV320ADC - SDOUT

DINP2 = TLV320ADC - GPIO1

Benno

0 Steve-Wilson over 5 years ago in reply to Benno Geels

TI__Mastermind 30220 points

Benno,

Is the audio capture distorted? What sampling rate is this?

best regards,

-Steve Wilson

0 Benno Geels over 5 years ago in reply to Steve-Wilson

Prodigy 60 points

Tis is at 48kHz sample rate and no input audio

Output is distorted. Due filtering the distorted output appears about 0.5 ms later on the analog out. It appears 4 samples later with 1 added to the input value on the digital DSP output. (marked in yellow below)

The 0x800000 sample is (marked in green) in below scope image