User guide

The complete user guide of the evaluation board can be found at CN0540 Reference Design.

Hardware guide

General Setup

Jumper Placement

The EVAL-CN0540-ARDZ Shield (CN0540 Board) includes a jumper that the user should be sure is placed in the correct position on P10. This jumper connects the current source to the circuit and may be removed for testing without a current source.

Sensor Input

The main input on the EVAL-CN0540-ARDZ is a right-angle SMA connector on the front of the board, as such it is highly recommended to connect the sensor using an SMA cable. If this is not possible, due to the type of sensor or otherwise, there is also the header P1 which can be connected to with standard wires. The software detailed below has an option to compensate for the voltage offset caused by a connected sensor which should always be run after connecting a new sensor.

LED Indicators

On the EVAL-CN0540-ARDZ board there are four LED lights. The PWR LED in the bottom-left corner indicates if the board is currently powered. LED1 and the CC LED, located in the top-right corner, indicate that the board is connected through the Arduino connectors. The FAULT LED is located just below them and indicates whether or not the switch’s fault flag is raised.

Arduino Interface

All connector pinouts for the EVAL-CN0540-ARDZ are described in the table below.

Connector

Pin No.

Pin Name

CN0540 Pin Function

Arduino DIO High

1

SCL

SCL

Arduino DIO High

2

SDA

SDA

Arduino DIO High

3

AREF

NC (Not connected)

Arduino DIO High

4

AGND

DGND

Arduino DIO High

5

SCLK

SCLK

Arduino DIO High

6

MISO

DOUT_RDYB

Arduino DIO High

7

MOSI

SDI

Arduino DIO High

8

CS

CS_ADC

Arduino DIO High

9

RDY

SHUTDOWN

Arduino DIO High

10

IO28

NC

Arduino DIO Low

1

IO08

RESET_ADC

Arduino DIO Low

2

IO27

SYNC_IN

Arduino DIO Low

3

IO33

CSB_AUX

Arduino DIO Low

4

IO09

SW_FF

Arduino DIO Low

5

IO13

DRDY_AUX

Arduino DIO Low

6

IO15

DRDY

Arduino DIO Low

7

TX

LED1

Arduino DIO Low

8

RX

LED2

Arduino Analog

1

AIN0

IO5

Arduino Analog

2

AIN1

IO4

Arduino Analog

3

AIN2

IO3

Arduino Analog

4

AIN3

NC

Arduino Analog

5

AIN4

NC

Arduino Analog

6

AIN5

IO0

Arduino Power

1

NC

NC

Arduino Power

2

IOREF

IOREF

Arduino Power

3

RESET

NC

Arduino Power

4

3.3V

3V3

Arduino Power

5

5V

NC

Arduino Power

6

GND

GND

Arduino Power

7

GND

GND

Arduino Power

8

Vin

NC

Piezo Accelerometer Sensor Results

To achieve reasonable noise measurements, the piezo accelerometer must be either stabilized using an active shaker table which cancels environmental vibrations or anchored to a massive object which makes sensor still. Anchoring to a massive object was used for a following measurements, where the piezo accelerometer was connected directly to the input of the signal chain.

The following figures show DC and AC coupled solution comparison, where the DC coupled version is producing more noise, but it is more linear. Whereas the AC coupled is nonlinear at very low frequencies (a spike near DC frequency bin), caused by a coupling capacitor.

FFT for the DC coupled solution with passively stabilized piezo sensor connected

(Optional) Hardware Interface

The board includes many ways in its hardware to interface with the components. These are optional interfaces that can be used to externally control aspects of the components.

Connector

Description

P7

Externally control the shift voltage, used in the piezo sensor bias voltage correction.

J2 & J3

Allows the user to input voltage while bypassing the front‑end, directly into the ADC driver.

J4

Externally provide the MCLK.

P6

Allows the user to use I2C protocol to provide the voltage supply, the SCL and SDA.

P8

PMOD connector allows the user to interface with the board without Arduino.

P9

Allows the user to connect a digital MEMS microphone and interact with it using the Arduino connectors.

Test Points

The board also has many test points, most of which are labelled and are fairly self-explanatory. The table below describes some of the most significant test points and their connections.

Test Point

Description

TP5

Connects to the 28V rail before it’s reduced to 26V.

TP6

Connects to the 7V rail before it’s reduced to 5V.

TP7

Connects to the +VS supply of the reference buffer.

TP8

Connects to pin 10 on the Arduino DIO high connector.

IO1

Connects to pin 5 on the Arduino Analog connector.

IO2

Connects to pin 4 on the Arduino Analog connector.

GPIO0

Connects to GPIO0 of the ADC.

GPIO1

Connects to GPIO1 of the ADC.

Schematic, PCB Layout, Bill of Materials

The archive EVAL-CN0540-ARDZ Design & Integration Files contains the following:

  • Schematics

  • PCB Layout

  • Bill of Materials

  • Allegro Project