AMS AS3460 User manual

User Guide
UG000480
AS3460
Digital Augmented Hearing Demo Kit
AS3460_EVALUATION_BOARD
v1-00 •2020-Jun-30

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Content Guide
1Introduction....................................3
1.1 Evaluation Kit ............................................... 3
1.2 Ordering Information .................................... 4
2Quick Start Guide ..........................5
2.1 Hardware Setup ........................................... 5
2.2 Project Setup................................................ 6
2.3 Measurements & Calibration........................ 6
2.4 Simulation Window....................................... 8
2.5 Filter Tuning ................................................. 9
3Evaluation Board.........................12
3.1 Default Jumper Setting...............................12
3.2 Power Supply.............................................13
3.3 Power ON/OFF...........................................18
3.4 Headphone Connectors............................. 19
3.5 Line Input Connectors................................21
3.6 Digital Microphone Connectors..................22
3.7 Raspberry Pi Board....................................25
3.8 I2C Communication .................................... 25
3.9 I2S Selection...............................................26
3.10 GPIO Buttons.............................................27
3.11 Measurement Header ................................28
3.12 AS3460 IC..................................................30
4PCB Design..................................32
4.1 PCB Layout Recommendation...................33
5FleX Software Manual..................40
5.1 Tab Structure ............................................. 42
5.2 Project Tab................................................. 43
5.3 System Configuration Tab ......................... 45
5.4 Routing Tab................................................ 48
5.5 Topology Tab............................................. 53
5.6 Tuning and Simulation Tab........................ 57
5.7 Calibration Tab........................................... 73
5.8 Debugging.................................................. 74
5.9 Register Map.............................................. 75
5.10 Watchers.................................................... 76
5.11 Importing Biquad Coefficients.................... 76
6ANC Tuning Guide....................... 82
6.1 Feedback ................................................... 82
6.2 Feed Forward............................................. 87
6.3 Example..................................................... 88
7Automatic Preset Selection
(APS) ............................................ 92
7.1 How Does Automatic Preset Selection (APS)
Work?......................................................... 92
7.2 Using APS in Flex...................................... 96
7.3 Simple APS Example................................. 97
8Revision Information................. 106
9Legal Information ...................... 107

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Introduction
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1 Introduction
The AS3460 is a digital augmented hearing companion device ideally suited for stereo headsets and
headphones as well as True Wireless applications. The extremely small form factor enables unique
augmented hearing experience for its end user with negligible influence on overall playtime of the
headset due to ultra-low power consumption. The high integration factor of AS3460 combined with its
all new Augmented Hearing Engine do allow for lowest power signal processing especially tailored for
the needs of active noise cancelling- and augmented hearing applications. The powerful low latency
digital signal processor (AHE) supports up to 250 Bi-Quad calculations to ideally match the
requirements of todays sophisticated acoustics designs and small form factors. Unique digital signal
processor (DSP) functions like seamless ANC crossfading or its integrated music feedback
compensation engine do allow lifting up user’s augmented hearing experience to its next level.
The development phase of such applications could be challenging and with this document, there are
some guideline listed to support customers in the product design. Below is a detailed description of the
AS3460 Evaluation Board and the configuration software FleX. Also some instructions are given
regarding ANC filter design.
The first section contains a quick start guide for the Evaluation Kit.
1.1 Evaluation Kit
The AS3460 Evaluation Kit package includes the following:
●AS3460 Evaluation Board
Figure 1:
Evaluation Board Hardware

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●FleX Filter Design Tool
This tool allows customers to design filters for the AS3460 ANC device.
Figure 2:
FleX Filter Design Tool Software
1.2 Ordering Information
Ordering Code
Description
AS3460_EVALUATION_BOARD
AS3460 Digital Augmented Hearing Demo Kit
For ordering of AS3460 devices:
Ordering Code
Package
Marking
Delivery Form
Delivery Quantity
AS3460-BFBT
FBGA36
[3.0 x 3.0 x 0.91 mm];
0.4 mm pitch
AS3460
Tape & Reel
5000 pcs/reel
AS3460-BFBM
FBGA36
[3.0 x 3.0 x 0.91 mm];
0.4 mm pitch
AS3460
Tape & Reel
500 pcs/reel

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2 Quick Start Guide
This section will explain some key features of FleX required for starting an ANC-Filter project.
To install the latest FleX software please visit: www.ams.com and login with your email address and
your password. If you do not have a login yet, please request one.
When successfully logged in, you can download the latest evaluation software in the products section
under tools.
Please make sure that you have connected the AS3460 Evaluation Board to your PC before you
install Flex Software the first time. This is mandatory for proper device driver installation.
2.1 Hardware Setup
To use FleX, it is necessary to connect the AS3460 Evaluation Board’s RaspberryPi via USB to a
windows computer. When connecting the RaspberryPi for the first time, it will show up as a mass
storage device, which contains the drivers that are required for FleX to function properly.
When creating a new project or opening an existing one, FleX will connect to the evaluation board.
The default IP-address and port for this is 169.254.0.2:8080
Figure 3:
Essential Connectors on the Evaluation Board
USB
Power Switch
3x PDM Input
L/R Headphone Differential Output

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2.2 Project Setup
The first step when starting with a blank FleX Project is to make the necessary hardware configuration
in the routing tab. Depending on the headphone’s wiring, the correct PDM microphone must be routed
to the corresponding filter. Here “DMIC 1L” refers to the first PDM interface, selecting on the rising
clock edge, “DMIC1R” is the microphone synced on the falling edge.
Figure 4:
Minimal Routing Configuration
2.3 Measurements & Calibration
Next is loading the XLS files obtained from the characterization (for more details see appendix A on
characterization) The AudioPrecision template provided by ams produces all the necessary files, with
the same naming scheme used by FleX.
Characterization data for several samples can be loaded, to check how the filter performs on the
various samples of the same headphone, thereby avoiding overfitting.

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Load data by navigating to the project tab and select the required files by clicking on the dots symbol
on each line.
Figure 5:
Measurement Sets
Depending on the measurement setup it will be necessary to calibrate the measurements. To do so
click on the eye symbol next to the affected measurement.
Example, if the measurement device’s output is balanced, but the headphone amplifier is connected
single-ended, the signal will lose 6dB, which then should be compensated for:

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Figure 6:
Gain and Phase Offset
If the headphone’s speaker is wired inverse to the AS3460 than it was wired at the time of
characterization it is necessary to compensate this using the “Phase offset”. It is not necessary to
calibrate for the test speaker or reference microphone, since their impact cancels out in the
calculations.
2.4 Simulation Window
The simulation window consists of three plots; the first two comprise a Bode-plot. In the Bode-plot the
ANC-filters and their target (or ideal Filter) can be viewed alongside each other. It is possible to drag
out the tuning tab and view it parallel to the filter tuning tab. This way it is possible to tune filters and
see the effect immediately. In the bottom plot FleX shows a prediction of the ANC-performance and
the total noise reduction.

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There are some basic controls for navigating the simulation window:
Figure 7:
Simulation Window Controls
Command
Action
Shift + Mouse wheel
Zoom with respect to frequency
Ctrl + Mouse wheel
Zoom with respect to Y-axis
Double Click inside plot
Reset view
Click + Hold
Drag plot
2.5 Filter Tuning
For tuning both a feed forward and a feedback system, FleX offers intuitive tuning of predefined filters.
For successful filter design it is crucial to be aware of how each filter type impacts both phase and
magnitude. The appendix contains a tutorial on how to tune the filters for feedback and feed
forward ANC.
There are three main types of filters available:
Figure 8:
Low/High Pass
●Adjustable
frequency
●Roll off of
-6 dB/Oct.
●-45° phase shift
at the roll off
frequency

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Figure 9:
Peak/Notch
Figure 10:
Shelf
Furthermore there is an Allpass filter and a 1st order x2 and you can also import biquad coefficients
into Flex so you can load all types of filters with that.
●Adjustable
frequency
●Gain
●And Q
●Adjustable
frequency
●Separate gains
for frequencies
higher and
lower than the
center
frequency
●Gain transition
with 6dB/Oct.