MCC 172
IEPE Measurement DAQ HAT for Raspberry Pi®
Features• Two IEPE inputs− Two 24-bit, 51.2 kS/s A/Dconverters (one per channel)− AC coupled at ±5 V
− 10-32 and screw terminal
connections for OEM support• Synchronous ADC conversions
between multiple boards
The MCC 172 is a 24-bit DAQ HAT for making sound and vibration measurements fromIEPE sensors. The MCC 172 is shown connected to a Raspberry Pi (not included).

Overview
The MCC 172 is a voltage HAT (Hardware Attached on Top) board designed for use
with Raspberry Pi, the most popular single-board computer on the market today.
A HAT is an add-on board with a 40W GPIO (general purpose input/output) connector that conforms to the Raspberry Pi HAT specification.
The MCC 172 HAT provides two analog inputs for sound or vibration measurements. Up to eight MCC HATs can be stacked onto one Raspberry Pi.

• Onboard sample buffers allow
high-speed acquisition• External digital trigger input• Stack up to eight MCC HATs
onto a single Raspberry PiSoftware• MCC DAQ HAT Library;
available on GitHub

Supported Operating Systems• Linux®/Raspbian

Raspberry Pi Interface

Multiple HAT Synchronization

The MCC 172 header plugs into the 40-pin
general purpose I/O (GPIO) connector on auser-supplied Raspberry Pi. The MCC 172
was tested for use with all Raspberry Pi
models with the 40-pin GPIO connector.

Multiple MCC 172 HATs can be synchronized to a single sampling clock. The clock is
programmable for sampling rates between
51.2 kS/s to 200 S/s.

HAT Configuration•

Single-board: max throughput is102.4 kS/s (51.2 kS × 2 channels)•Stacked boards: max throughput is307.2 kS/s aggregate1.

HAT configuration parameters are stored
in an on-board EEPROM that allows theRaspberry Pi to automatically set up theGPIO pins when the HAT is connected.

Sample Rates

Digital Trigger

Stackable HATs
Up to eight MCC HAT boards can bestacked onto a single Raspberry Pi.
Users can mix and match MCC HAT
models in the stack.

Analog Input
The two 24-bit differential analog input
channels simultaneously acquire data atrates up 51.2 kS/s. Users can turn IEPE
excitation current on or off.
Each channel has a dedicated A/D converter. Both ADCs share the same clock
and are synchronized to start conversions
at the same time for synchronous data.

The trigger input (terminal TRIG) is used
to delay an input scan until a specified
condition is met at the trigger input.
The trigger input signal may be a 3.3V or
5V TTL or CMOS logic signal. The input
condition may be edge or level sensitive,rising or falling edge, or high or low level.
This terminal may be used to trigger thestart of an acquisition on multiple synchronized MCC 172 HATs.

PowerProgramming API• C, C++, PythonOEM Support
Users can connect analog input signals toeither the 10-32 coaxial inputs or to thescrew terminals. Only one source may beconnected to a channel at a time.

MCC DAQ HAT Library
The open-source MCC DAQ HAT Libraryof commands in C/C++ and Python
allows users to develop applications on
the Raspberry Pi using Linux.
The library is available to download fromGitHub. Comprehensive API and hardware documentation is available.
The MCC DAQ HAT Library supports
operation with multiple MCC DAQ HATs
running concurrently.
Console-based and user interface (UI)
example programs are available for eachAPI.

The MCC 172 is powered with 5 Vprovided by the Raspberry Pi through theGPIO header connector.
1 Dependent on the load on the Raspberry Pi andthe SPI interface.

Measurement Computing(508) 946-5100

1

info@mccdaq.com

mccdaq.com

MCC 172
Block Diagram

+5V

IEPE
Supply3.3V
SupplyClock

CH 0Amp

Clock
Master/Slave
IEPE
SupplyCH 1

Amp

26.2144
MHz
Oscillator

ADC
Clock

32-bitMicrocontroller

SPI

SPI

Board
AddressMatching

Raspberry PiHeader

ADC
HATEEPROM
Trigger
Master/Slave

DigitalTrigger

I2CTrigger Bus
Clock Bus

Stackable
Connect up to eight MCC DAQ HATs onto a single
Raspberry Pi.
Onboard jumpers identify each board in the stack.

Measurement Computing(508) 946-5100

2

info@mccdaq.com

mccdaq.com

MCC 172
Example Programs
MCC DAQ HAT Examples

User Interface

The MCC DAQ HAT Library includes example programs developed in C/C++ and Python that users can run to become familiar
with the DAQ HAT library and boards; source code is included.

Example programs featuring a user interface are provided indifferent formats. Examples of each are shown here.

Console-Based (C/C++ and Python)

The data logger example shows how to acquire data from theMCC 172, display the data on a strip chart, and log the data toa CSV file. This example can be run from the terminal.

Data Logger (C/C++)

Console-based examples are provided that demonstrate how
to perform FFT on a block of data, acquire synchronous datafrom multiple MCC 172 HATs using shared clock and trigger
options, trigger a finite scan, and synchronously acquire datafrom multiple DAQ HATs. Source code is included.
The fft_scan example is shown here.

Configure options, plot data on a strip chart, and log data to a file

Web Server (Python)

The web server example lets users configure acquisition optionsand view acquired data from a browser window. This example
is written for Python (source included).
Peak frequency and harmonics display in a terminal window

Configure options and view strip chart data from your browser
FFT data is saved to a csv file

Measurement Computing(508) 946-5100

3

info@mccdaq.com

mccdaq.com

MCC 172Specifications
Accuracy

All specifications are subject to change without notice.
Typical for 25 ˚C unless otherwise specified.

Analog input AC voltage measurement accuracy(all values are (±) and apply to calibrated readings)

Analog input

Number of channels: 2ADC Resolution: 24 bits
A/D converter type: Delta sigma
Sampling mode: Simultaneous
Master timebase (fM):
Frequency: 26.2144 MHz
Accuracy: ±50 ppm max
Master timebase sources
Internal clock
Shared clock from another MCC 172
Data rates (fS)
(fM / 512) / n, n = 1, 2, …, 256
51.2 kS/s max
200 S/s min
Input coupling: ACAC cutoff frequency-3 dB: 0.78 Hz-0.1 dB: 5.2 Hz max
Input voltage range: ±5 V
Common-mode voltage range
CHx to AGND: ±2 V max
Overvoltage protection
CHx+ to CHx-: ±35 V
CHx- to ground: ±2.5 V
IEPE compliance voltage: 23 V max
IEPE excitation current: 4.0 mA min, 4.1 mA typ
Input delay
1 kHz to 23 kHz input frequency: 4.5 µs + 39 / fS
Channel-to-channel matching
Phase (200 Hz to 23 kHz): (fin * 0.022°) max
Gain (20 Hz to 23 kHz): 0.19 dB typPassband
Frequency: 0.453 * fS
Flatness (20 Hz to 23 kHz): 52 mdB (pk-to-pk max)
Phase nonlinearity
fS = 51.2 kS/s, 200 Hz to 23 kHz input frequency: ±0.36° max
StopbandFrequency: 0.547 * fS
Rejection: 99 dB min
Alias-free bandwidth: 0.453 * fS
Alias rejection: 100 dB @ 51.2 kS/s
Oversample rate: 128 * fS
Crosstalk1 kHz: -122 dB
SFDR
fin = 1 kHz, -60 dBFS: 120 dB
Dynamic range
fin = 1 kHz, -1 dBFS: 100 dB
Input impedanceDifferential: 202 kΩAI- (shield) to ground: 50 ΩThroughput
Single board: 102.4 kS/s max (51.2 kS/s × 2 channels)
Multiple boards: Up to 307.2 kS/s aggregate††Depends on the load on the Raspberry Pi processor and the SPI interface.

(508) 946-5100

Offset error,max:Gain temperature
coefficient, max:

Gain temperature
coefficient, max:

0.43%

5.10 mV

88 ppm/°C

184 µV/°C

Noise performance
Idle Channel

51.2 kS/s

Noise

33 µVrms

Noise density

207 nV/√Hz

Total harmonic distortion (THD)
Input Amplitude

1 kHz

8 kHz

-1 dBFS-93 dB-91 dB-10.96 dBFS

-87 dB-87 dB

External digital triggerTrigger source: TRIG input
Trigger mode: Software configurable for rising or falling edge, or high or low level
Trigger latency: 1 µs + 1 sample period (1/fS) max
Trigger pulse width: 100 ns min
Input type : Schmitt trigger, 100K pull-down to ground
Input high voltage threshold: 1.48 V min
Input low voltage threshold: 1.2 V max
Input hysteresis: 0.51 V min
Input voltage limits: 6.5 V absolute max, –0.5 V absolute min,0 V recommended min

MemoryData FIFO: 48 K (49,152) analog input samples
Non-volatile memory: 4 KB (ID and calibration storage, no user-modifiablememory)

Power

Supply current, 5 V supply
Typical: 100 mA
Maximum: 140 mAInterface

Raspberry Pi GPIO pins used:
GPIO 8, GPIO 9, GPIO 10, GPIO 11 (SPI interface)
ID_SD, ID_SC (ID EEPROM)
GPIO 12, GPIO 13, GPIO 26 (Board address)
GPIO 5, 6, 19, 16, 20 (Clock / trigger sharing, Reset, IRQ)
Data interface type: SPI slave device, CE0 chip selectSPI mode: 1
SPI clock rate: 18 MHz, max

Environment

Operating temperature: 0 °C to 55 °C
Storage temperature: –40 ˚C to 85 °C max
Relative humidity: 0% to 90% non-condensing

MechanicalNote: For best results, connect the signal source and the Raspberry Pi to a commonground. If a floating source is required, connect the MCC 172 to earth ground via
the DGND screw terminal to minimize common mode noise.

Measurement Computing

Gain error,max:

Dimensions (L × W × H): 65 × 56.5 × 12 mm (2.56 × 2.22 × 0.47 in.) max

4

info@mccdaq.com

mccdaq.com

MCC 172
Ordering
Signal connectors

Trigger input screw terminal pinout (Connector J5)

Connector types: 10-32 coaxial / screw terminal (in parallel; only one source may
be connected to a channel at a time)
Coaxial input signals
CH0: channel 0 input
CH1: channel 1 input
Screw terminal wire gauge range: 16 AWG to 30 AWG

PinSignal namePin description

1TRIG

Digital trigger input

2

GND

Digital ground

Analog input screw terminal pinout (Connector J2)
Pin

Signal namePin description

1

CH0+

Channel 0 positive input

2

CH0-

Channel 0 negative input

3

CH1+

Channel 1 positive input

4

CH1-

Channel 1 negative input

Order Information

SoftwareHardwarePart No.

Description

MCC DAQ
HAT Library

Open-source library for developing applications in C, C++,and Python on Linux for MCC DAQ HAT hardware.
Available for download on GitHub at https://github.com/
mccdaq/daqhats.

Part No.

Description

MCC 172

24-bit, 2-channel IEPE measurement DAQ HAT.
Raspberry Pi with the 40-pin GPIO connector required.

Accessories
Part No.

Description

ACC-172

Coaxial cable, 3 ft, with 10-32 plug to BNC jack (2 qty)

Measurement Computing
DS-MCC-172(508) 946-5100

5

info@mccdaq.com

mccdaq.com
April 2021. Rev 3© Measurement Computing Corporation