miniDSP UMA-16 User manual

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UMA-16
MICROPHONE ARRAY DEVELOPMENT BOARD
User Manual

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Revision history
Revision
Description
Date
V1.0
First version
18 Jan 2018
V1.1
Updated for MCHStreamer Lite interface (preliminary)
17 May 2022

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TABLE OF CONTENTS
Table of contents ............................................................................................................................................. 3
IMPORTANT INFORMATION ............................................................................................................................. 4
1 Product Overview ...................................................................................................................................... 6
2 Board Layout and Connectivity .................................................................................................................. 7
2.1 Board layout .............................................................................................................................................. 7
2.2 USB Connectivity ....................................................................................................................................... 8
2.3 Knowles SPH1668LM4H-1 microphones ................................................................................................... 8
3 USB Audio ................................................................................................................................................ 10
3.1 macOS ..................................................................................................................................................... 10
3.2 Windows ................................................................................................................................................. 11
3.2.1 USB Driver installation ..................................................................................................................... 11
3.2.2 Status ............................................................................................................................................... 11
3.2.3 Buffer settings ................................................................................................................................. 12
3.2.4 Volume ............................................................................................................................................ 12
3.2.5 Info .................................................................................................................................................. 13
3.3 Compliant USB audio software ............................................................................................................... 13
4 Custom Microphone Board Development ................................................................................................ 14
4.1 Headers and pinouts ............................................................................................................................... 14
4.2 PDM overview ......................................................................................................................................... 16
5 Additional Information ............................................................................................................................ 17
5.1 Specifications .......................................................................................................................................... 17
5.2 MCU firmware update ............................................................................................................................. 18
5.2.1 Windows .......................................................................................................................................... 18
5.3 Obtaining support ................................................................................................................................... 20
5.4 Schematics .............................................................................................................................................. 20

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IMPORTANT INFORMATION
Please read the following information before use. In case of any questions, please contact miniDSP via the
support portal at support.minidsp.com.
System Requirements
To configure the UMA-16, you will require a Windows PC or Apple Mac computer with the following minimum
specification:
Windows
• Microsoft• ® Windows® 7/8.1/10/11
• At least a dual core i3, i5, or i7 processor
• At least 2 GB RAM (4 GB or more preferred)
• One free USB 2.0 port
• Internet connection
macOS
• OS X 10.8 or higher, macOS 10.12 or higher
• At least a dual core i3, i5, or i7 processor, or an ARM processor (M1/Pro/Max)
• At least 2 GB RAM (4 GB or more preferred)
• One free USB 2.0 port
• Internet connection
Disclaimer/Warning
miniDSP cannot be held responsible for any damage that may result from the improper use of this product or
incorrect configuration of its settings. As with any other product, we recommend that you carefully read this
manual and other technical notes to ensure that you fully understand how to operate this product. The miniDSP
audio processor is a powerful tool, and misuse or misconfiguration, such as incorrectly set gains or excessive
boost, can produce signals that may damage your audio system.
As a general guideline, you should perform the initial configuration of the miniDSP audio processor before
enabling audio through any connected output device or amplification. Doing so will help ensure that the
software is correctly configured.
Finally, note that the miniDSP audio processor is a very flexible device, and many of the questions we receive at
the tech support department are already answered in this user manual and in the online application notes on
the miniDSP.com website. So please take the time to carefully read this user manual and the online technical
support. Thanks for your understanding!
Warranty Terms
miniDSP Ltd warrants this product to be free from defects in materials and workmanship for a period of one
year from the invoice date. Our warranty does not cover failure of the product due to incorrect connection or
installation, improper or undocumented use, unauthorized servicing, modification or alteration of the unit in any
way, or any usage outside of that recommended in this manual. If in doubt, contact miniDSP prior to use.

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FCC Class B Statement
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
• This device may not cause harmful interference.
• This device must accept any interference received, including interference that may cause undesired
operation.
Warning: This equipment has been tested and found to comply with the limits for a Class B digital device,
pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection. This
equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance
with the instructions, may cause interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful interference to radio
or television reception, which can be determined by turning the equipment off and on, the user is encouraged to
try to correct the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
Notice: Shielded interface cable must be used in order to comply with emission limits.
Notice: Changes or modification not expressly approved by the party responsible for compliance could void the
user’s authority to operate the equipment.
CE Mark Statement
The miniDSP UMA-16 has passed the test performed according to European Standard EN 55022 Class B.
A note on this manual
This User Manual is designed for reading in
both print and on the computer. If printing
the manual, please print double-sided. The
embedded page size is 8 ½” x 11”. Printing on
A4 paper will result in a slightly reduced size.
For reading on the computer, we have
included hyperlinked cross-references
throughout the manual. In addition, a table of
contents is embedded in the PDF file. Use the
View menu (Preview on Mac) or the
bookmarks sidebar (Adobe reader on Mac and
Windows) to view this table of contents.
Acknowledgments
ASIO® is a registered trademark of Steinberg Media Technologies GmbH.

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1 PRODUCT OVERVIEW
Thank you for choosing the UMA-16 audio processor board. The UMA-16 is a cost effective sixteen-channel
microphone array with plug-and-play USB audio connectivity. With its embedded XMOS interface, the UMA-16 is
the perfect fit for researchers looking to develop their own beam forming algorithms.
The UMA-16 system architecture is powered by two core elements:
- A microphone array PCB with 16 x SPH1668LM4H MEMS Knowles with PDM outputs. A center hole fits an
optional USB camera perfect in applications such as acoustic cameras. The microphone array is a simple 2-
layer design that can easily be customized to your needs by following our schematics included in this user
manual.
- Stacked on top of the mic array is the MCHStreamer Lite USB interface. This XMOS XCORE multicore CPU
allows for a high quality PDM to PCM conversion and presents all 16 channels of raw audio to the ASIO USB
audio driver.
Please note that the following sections will highlight basic operation of the UMA-16. Beamforming algorithm
development or any 3rd party support for software (e.g. Matlab) is considered outside the scope of this manual
and our support structure.

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2 BOARD LAYOUT AND CONNECTIVITY
2.1 BOARD LAYOUT
The below diagram shows the layout of the UMA-16 board. Sixteen MEMS microphone are laid out in a Uniform
Rectangular Array (URA) distribution, with microphone offset set to 42mm. CAD drawings are available on
request.

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2.2 USB CONNECTIVITY
Connect the USB port (type B) to a computer. The USB port provides asynchronous USB Audio (Class 2)
streaming at the sample rates 14.7/11.025/12/16/22.05/44.1/48kHz. See section 3 for more details on USB
audio connectivity
The array is powered over the USB connection, so there is no need to separately connect power.
2.3 KNOWLES SPH1668LM4H-1 MICROPHONES
The UMA-16 is fitted with 16 Knowles MEMS microphones. Please refer to the complete datasheet for more
details.
Features
• Low Distortion of 1.6% at 120dBSPL
• High SNR of 65.5dB
• Flat Frequency Response
• RF Shielded
• Zero-Height Mic™
• Supports Dual Multiplexed Channels
• Standard SMD Reflow
• Omnidirectional

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Acoustic performance under the Performance Mode (default)

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3 USB AUDIO
The miniDSP UMA-16 streams PCM audio at sample rates of 14.7k/11.025k/12k/16k/22.05k/44.1k/48k over its
USB Audio Class 2 (UAC2) compliant interface. Here are more details on setup and configuration.
3.1
MACOS
Open the program Audio MIDI Setup (in Applications->Utilities). The UMA-16 will appear as “MCHStreamer
micArray 16” in the list on the left-hand side. Clicking on it will show the input and output channels. Sample rate
can be selected in the dropdown menus:

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3.2 WINDOWS
3.2.1 USB Driver installation
1. Connect the UMA-16 to the computer using the supplied USB cable, and power it on with the 12V
supply.
2. Navigate to the WinDrivers folder of the software download and double-click on the installer:
• miniDSP_UAC2_v3.34.0_ForWin7_8_10.exe for Windows 7 or later (The version number embedded in
the filename may be different.)
We recommend accepting the default installation location. Once the driver installation completes, click the
Finish button.
The Windows PC will not be able to communicate properly with the UMA-16 if you did not have it
connected by USB and powered on when you installed the driver. If that is the case, you will need to
uninstall the driver, connect the UMA-16, power it on, and run the installer again.
To configure the UMA-16, open the miniDSP UAC2 Control Panel (from Start Menu -> miniDSP Ltd). It has
several panes, described below.
3.2.2 Status
This panel shows the current sample rate of the UMA-16. This setting cannot be changed in the Control panel,
but simply reflects the current sample rate of the UMA-16. This setting will be affected by the recording
software when the USB audio stream starts.

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3.2.3 Buffer settings
The buffer settings are for those looking to optimize buffering and latency settings. Note that changing these
settings may result in unstable operation. For example, the lowest latency settings require high amounts of CPU
and memory, and may not work on some machines. If you do not require lowest latency, we recommend that
you do not depart from the default safe settings.
3.2.4 Volume
This panel contains the volume controls for input channels.
o To reset the master volume control or a pair of channels to 0 dB (no attenuation), click the 0dB button.
o To mute all channels, click either of the speaker icons.
o To control volume separately for each channel, click on the “Link” icon to turn it off

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3.2.5 Info
This panel shows information about the UMA-16. Important data includes the firmware and driver versions.
3.3 COMPLIANT USB AUDIO SOFTWARE
Please note that the UMA-16 requires a multichannel recording software with ASIO support. Not all software
supports such needs. For example, the Audacity freeware only supports WDM and therefore won’t work.
We recommend a Digital Audio Workstation (DAW) such as Reaper/Cubase/Protools for a reliable experience.
Also note that Matlab running the latest audio toolbox will support ASIO fine. Please consult Matlab tech
support for more details. For an introduction to using the UMA-16 with Matlab, see this app note on our
website:
• Using the miniDSP UMA-16 / UMA-8 microphone array with Matlab

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4 CUSTOM MICROPHONE BOARD DEVELOPMENT
In an effort to help the community, miniDSP is providing full schematics of the microphone board PCB
(nanoSHARC kit not included). Please consult the appendix at the end of this manual. Based on a simple 2-layer
design, one can easily route a test PCB to trial various microphone arrangements.
NOTE: Electronic engineering support is unfortunately outside miniDSP’s support structure. If
you were to design your own MEMS array and lack the engineering knowledge to do so, we
strongly recommend that you to seek 3rd party engineering support. Thanks for your
understanding!
4.1 HEADERS AND PINOUTS
The MCHStreamer Lite circuit board has three 12-pin headers for logic-level I/O, as shown in Figure 1 below.
Most data lines are on header J1, while J2 carries auxiliary signaling and GPIO lines reserved for future
enhancement. J3 is used only for PDM format. Two cables terminated with suitable (2x6, 2mm pitch) 12-pin
headers are supplied with the MCHStreamer Lite kit version.
All lines are 3.3V logic levels. Connected circuits must use a compatible logic level.
Figure 1. MCHStreamer Lite board layout

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The UMA-16 firmware supports 16 input channels at 8, 11.025, 12, 16, 32, 44.1 and 48 kHz. PDM input data is
received on J3, with two channels per physical data line. These 16 channels are mirrored in I2S format on J1 and
are also received by the computer over USB.
Table 1. PDM firmware pinouts
J1 pin
J3 pin
1
PDM Rx 1-2
1
GND
2
PDM Rx 9-10
2
3.3V
3
PDM Rx 3-4
3
PDM 1-2
4
PDM Rx 11-12
4
PDM 3-4
5
PDM Rx 5-6
5
PDM 5-6
6
PDM Rx 13-14
6
PDM 7-8
7
PDM Rx 7-8
7
PDM 9-10
8
PDM Rx 15-16
8
PDM 11-12
9
MCLK
9
PDM 13-14
10
BCLK
10
PDM 15-16
11
GND
11
PDM CLK
12
LRCLK
12
PDM CLK2
Figure 2. PDM firmware signal flow

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4.2 PDM OVERVIEW
PDM stands for Pulse Density Modulation. It is an ideally suited digital audio transmission method for MEMS
microphone as it brings benefits of digital audio (noise immunity, high quality audio) at very low cost.
PDM CLK The PDM clock always runs at 3.072MHz.
PDM[0..7] Each data lines carrying a stereo feed of 2 x microphones by using the SELECT PIN. The timing of
data lines is as illustrated in the following diagram:
The UMA-16 uses one stereo PDM data line for two mics with a standard configuration as per Knowles app note.
All lines use a 3.3V logic level. Ensure that connected circuits use a compatible logic level.

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5 ADDITIONAL INFORMATION
5.1 SPECIFICATIONS
Item
Description
Control
Driverless USB 2.0 control interface for Windows/macOS environments
A computer is only required for the initial configuration and for USB audio
streaming
USB audio input
XMOS Xcore200 asynchronous USB audio up to 48 kHz, USB Audio Class 2
compliant
• ASIO drivers for Windows
• Driverless for macOS
PDM inputs
Up to 16 x MEMS microphone connections (8 x stereo PDM data lines)
MEMS microphone on UMA-16
16 x SPH1668LM4H
ADC/DAC Sample rate &
Resolution
Resolution: 24 bit
Sample rate: 14.7k/11.025k/12k/16k/22.05k/44.1k/48k
USB port
USB port type B for audio streaming, real time control and firmware upgrade
Power supply
Provided over USB
Dimensions (H x W x D) mm
132 x 195 x 30 mm
Mounting
4 x M3 holders for front panel mounting / CAD drawings available on request

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5.2 MCU FIRMWARE UPDATE
5.2.1 Windows
1. Connect the UMA-16 to your computer via USB (if not already connected) and power it on.
2. Start the miniDSP UAC2 DFU Tool.
3. The upgrade program will start:

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4. Click on the Browse button, navigate to the folder XMOS_Firmware in the plugin download folder, and
select the firmware file.
5. Click on the Start button.
6. You will get a progress bar as upgrade proceeds:
7. Once the firmware upgrade completes, you will see a message that the upgrade completed successfully:
8. Click on Exit.

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5.3 OBTAINING SUPPORT
1. Check the forums on miniDSP.com to see if this issue has already been raised and a solution provided.
2. Contact miniDSP via the support portal at minidsp.desk.com with:
a. The specific product you are having an issue with (in this case, UMA-16 board or accessories).
b. A clear explanation of the symptoms you are seeing.
c. A description of troubleshooting steps (see Troubleshooting above) performed and your results.
Please note that miniDSP is only able to provide support for the hardware and functions documented in this
manual, and only for problems specifically related to the miniDSP hardware and software functions. Any other
items, such as designing or debugging your PDM interface circuitry or layout or interfaces to third-party
hardware, are specifically excluded from the scope of miniDSP support.
5.4 SCHEMATICS
See next two pages.