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TLV320AIC3253: Using this codec with a PDM digital microphone but only get loud white noise

Part Number: TLV320AIC3253

Using TLV320AIC3253 codec with PDM Microphone Invensense MMICT390200012.

On both the prototype PCBA and EVK we only get Loud white noise. We can adjust the gains to lower the amount of white noise but we cannot hear any real audio.

I am wondering if there is a preferred PDM digital microphone for use with this codec?
    From what we can see we are getting a 4 MHz Square wave, but not quite 50% D.C. from the codec (more like 55 / 45 % )
    the data coming from the microphones appears to be what we would expect it to be. That is to say there are transitions sync'ed to the clock and some modulation that changes with excitation (tones from a speaker and function gen)

The script that we pulled form the EVM software to set up the codec is listed below :

###############################################
# Digital Microphone Script Loopback
# ---------------------------------------------
# Digital microphone data (DOUT) is sent to
# the DAC's DIN pin internally. DOUT data
# is also sent to the USB controller.
###############################################



###############################################
# Software Reset
###############################################
#
# Select Page 0
w 30 00 00
#
# Initialize the device through software reset
w 30 01 01
#
###############################################



###############################################
# Clock and Interface Settings
# ---------------------------------------------
# The codec receives: MCLK = 11.2896 MHz,
# WCLK = 44.1 kHz
###############################################
#
# Select Page 0
w 30 00 00
#
# PLL_clkin = MCLK, codec_clkin = PLL_CLK,
# PLL on, P=1, R=1, J=8, D=0000
w 30 04 03 91 08 00 00
#
# NDAC = 2, MDAC = 8, dividers powered on
w 30 0b 82 88
#
# DOSR = 128
w 30 0D 00 80
#
# NADC = 2, MADC = 16, dividers powered on
w 30 12 82 90
#
# AOSR = 64
w 30 14 40
#
# Digital Loopback
# Routes DOUT to DIN internally, DOUT pin
# is still output, DIN pin is ignored
w 30 1D 10
#
###############################################



###############################################
# Configure Power Supplies
###############################################
#
# Select Page 1
w 30 00 01
#
# Disable weak AVDD in presence of external
# AVDD supply
w 30 01 08
#
# Enable Master Analog Power Control
w 30 02 00
#
# Set the input power-up time to 3.1ms (for ADC)
w 30 47 32
#
# Set the REF charging time to 40ms
w 30 7b 01
#
###############################################



###############################################
# Configure Processing Blocks
###############################################
#
# Select Page 0
w 30 00 00
#
# PRB_P2 and PRB_R2 selected
w 30 3C 02 02
#
################################################
# High-pass first order Butterworth2 filter,
# fc = 80 Hz
###############################################
#
# Write to Buffer A:
#
# BIQUAD A, Left Channel (Page 8, Register 36, C7-C11)
w 30 00 08
w 30 24 7E F8 EB 00 81 07 15 00 7E F8 EB 00 7E F7 DD 00 82 0C 0C 00
#
# BIQUAD A, Right Channel (Page 9, Register 44, C39-C43)
w 30 00 09
w 30 2c 7E F8 EB 00 81 07 15 00 7E F8 EB 00 7E F7 DD 00 82 0C 0C 00
#
# Write to Buffer B:
#
# BIQUAD A, Left Channel (Page 26, Register 36, C7-C11)
w 30 00 1A
w 30 24 7E F8 EB 00 81 07 15 00 7E F8 EB 00 7E F7 DD 00 82 0C 0C 00
#
# BIQUAD A, Right Channel (Page 27, Register 44, C39-C43)
w 30 00 1B
w 30 2c 7E F8 EB 00 81 07 15 00 7E F8 EB 00 7E F7 DD 00 82 0C 0C 00
#
###############################################




###############################################
# Configure ADC Channel
###############################################
#
# Select Page 0
w 30 00 00
#
# Configure MISO as clock output for DIGMIC
w 30 37 0E
#
# LADC and RADC enabled for DIGMIC
# Route SCLK as DIGMIC_DATA
# Power up LADC/RADC
w 30 51 DC
#
# Unmute LADC/RADC
w 30 52 00
#
###############################################



###############################################
# Configure DAC Channel
###############################################
#
# Select Page 1
w 30 00 01
#
# De-pop: 5 time constants, 6k resistance
w 30 14 25
#
# Route LDAC/RDAC to HPL/HPR
w 30 0c 08 08
#
# Select Page 0
w 30 00 00
#
# DAC => 0dB
w 30 41 00 00
#
# Power up LDAC/RDAC
w 30 3f d6
#
# Select Page 1
w 30 00 01
#
# Unmute HPL/HPR driver, 0dB Gain
w 30 10 00 00
#
# Power up HPL/HPR
w 30 09 30
#
# Select Page 0
w 30 00 00
#
# Unmute LDAC/RDAC
w 30 40 00
#
#############################################
  • Hi,

    There's no preferred DMIC mentioned in the datasheet, but I will check internally just to make sure.

    I checked on the EVM with a DMIC similar to this MP34DT01-M using the preset configuration like the above and I can hear the recording.

    Here is the DCLK and Data as well as the recording export from Audacity without any white noise just the tone.

    Click here to play this audio clip

    Regards,

    Peter

  • Is the script you used "exactly" like the above?

    Can you please provide your script so we can check it against ours?

  • Is the script you used "exactly" like the above?

    Can you please provide your script so we can check it against ours?

  • Yes, it is. Here is a copy of it.

    DMIC loopback script from AIC3253 GUI.txt
    Fullscreen
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    ###############################################
    # Digital Microphone Script Loopback
    # ---------------------------------------------
    # Digital microphone data (DOUT) is sent to
    # the DAC's DIN pin internally. DOUT data
    # is also sent to the USB controller.a
    ###############################################
    ###############################################
    # Software Reset
    ###############################################
    #
    # Select Page 0
    w 30 00 00
    #
    # Initialize the device through software reset
    w 30 01 01
    XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

    Regards,

    Peter