Analog Devices EVAL-ADuCM355QSPZ User manual

EVAL-ADuCM355QSPZ Evaluation Board
UG-1308
One Technology Way •P.O. Box 9106 •Norwood, MA 02062-9106, U.S.A. •Tel: [phone] •Fax: [phone] •www.analog.com
Evaluating the ADuCM355 Precision Analog Microcontroller
with Chemical Sensor Interface
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS. Rev. A | Page 1 of 24
FEATURES
Debug and programming capability of the ADuCM355
Evaluation capability with electrochemical gas sensors
ADT7420 ±0.25°C accurate temperature sensor via I2C
MicroUSB power option and connection to PC
EQUIPMENT NEEDED
PC running Windows® 7 or later
Electrochemical gas sensor or resistor star network
DOCUMENTS NEEDED
ADuCM355 hardware reference manual
ADuCM355 data sheet
SOFTWARE NEEDED
IAR Embedded Workbench or Keil μVision
ADuCM355 GitHub Repository
Terminal program such as RealTerm
GENERAL DESCRIPTION
The ADuCM355 on-chip system provides the features needed
to bias and to measure a range of different electrochemical
sensors. The EVAL-ADuCM355QSPZ allows users to evaluate
the performance of the ADuCM355 when implementing a
range of different electrochemical techniques, including
chronoamperometry, voltammetry, and electrochemical
impedance spectroscopy (EIS).
Complete specifications for the ADuCM355 are available in the
ADuCM355 data sheet, which must be consulted in conjunction
with this user guide when using the EVAL-ADuCM355QSPZ.
EVALUATION BOARD PHOTOGRAPH
16887-001
Figure 1.

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 2 of 24
TABLE OF CONTENTS
Features.............................................................................................. 1
Equipment Needed........................................................................... 1
Documents Needed.......................................................................... 1
Software Needed............................................................................... 1
General Description ......................................................................... 1
Evaluation Board Photograph ........................................................ 1
Revision History ............................................................................... 2
Power Configurations...................................................................... 4
MicroUSB Direct Power via P4 and ADP7158 LDO
Regulator ....................................................................................... 4
Direct 3.3 V Power via the AVDD and DVDD Connectors.. 6
Power via USB from 8-Pin DEBUG Connector (P27)............ 6
Power via External 5 V Supply to 2-Pin Connector (P37) ..... 6
Connecting an Electrochemical Sensor......................................... 7
Getting Started with the Tool Chain ............................................. 8
Downloading the Integrated Development Environment
(IDE) .............................................................................................. 8
Installing the ADuCM355 Support Package ............................ 8
Running a GPIO Example in IAR Embedded Workbench ....8
Running a GPIO Example in Keil μVision............................. 11
Application Examples.................................................................... 13
Cyclic Voltammetry Example .................................................. 13
EIS Example ................................................................................ 14
Chronoamperometry Example ................................................ 14
DC Current Example................................................................. 15
4-Lead Electrochemical Sensor Example................................ 16
Connecting an External Gain Resistor Across the High Speed
TIA ............................................................................................... 17
AFE Die Watchdog Timer Example........................................ 17
ADuCM355 System Calibration .................................................. 18
High Speed TIA Gain Resistor Calibration............................ 18
Low Power TIA0/TIA1 Gain Resistor Calibration ............... 20
Mass Erasing a Device Not Responding to SWD Commands. 22
Ordering Information.................................................................... 23
Bill of Materials .......................................................................... 23
REVISION HISTORY
4/2021—Rev. 0 to Rev. A
Changes to Features Section, Equipment Needed Section,
Software Needed Section, and General Description Section ..... 1
Deleted MicroUSB Connector, P4 Setup Section Heading ........ 4
Changes to Power Configurations Section, MicroUSB Direct
Power via P4 and ADP7158 LDO Regulator Section, and
Figure 2 Caption............................................................................... 4
Changes to Direct 3.3 V Power Via the AVDD and DVDD
Connectors Section, Jumper Setup with Direct 3.3 V Connection
Section, Power via USB from 8-Pin Debug Connector (P27)
Section, Jumper Setup with Power via USB Section, Figure 5
Caption, and Power via External 5 V Supply to 2-Pin Connector
(P37) Section ..................................................................................... 6
Changes to Connecting an Electrochemical Sensor Section...... 7
Deleted Figure 8; Renumbered Sequentially ................................ 7
Changed Getting Started with the Tool Chain Section to
Getting Started with the Tool Chain Section ............................... 8
Changes to Downloading the Integrated Development
Environment (IDE) Section, Installing the ADuCM355 Support
Package Section, Running a GPIO Example in IAR Embedded
Workbench Section, and Project Folder Structure Section........ 8
Replaced Figure 9 ............................................................................. 9
Changes to Compiling and Running Firmware Section and
Figure 11 Caption........................................................................... 10
Replaced Figure 10 and Figure 12................................................ 10
Replaced Figure 14 ......................................................................... 11
Added Running a GPIO Example in Keil μVision Section,
Figure 15, and Figure 16; Renumbered Sequentially ................ 11
Deleted Figure 19 ........................................................................... 11
Added Figure 17 to Figure 19 ....................................................... 12
Changes to Application Examples Section, Cyclic Voltammetry
Example Section, and Figure 22 Caption.................................... 13
Added Figure 21 ............................................................................. 13
Changes to Figure 23 Caption, EIS Example Section, and
Chronoamperometry Example Section ...................................... 14
Replaced Figure 23 and Figure 25................................................ 14
Added Figure 24 ............................................................................. 14
Replaced Figure 28 and Figure 29................................................ 15
Changes to Figure 28 Caption and DC Current
Example Section ............................................................................. 15
Changes to 4-Lead Electrochemical Sensor
Example Section ............................................................................. 16
Added Figure 30 ............................................................................. 16
Moved Connecting an External Gain Resistor Across the High
Speed TIA Section, AFE Watchdog Timer Example Section,
and Figure 32 .................................................................................. 17
Changes to AFE Die Watchdog Timer Example Section ......... 17
Added ADuCM355 System Calibration Section ....................... 18
Moved High Speed TIA Gain Register Calibration Section..... 18
Deleted Figure 29 ........................................................................... 18
Changes to High Speed TIA Gain Resistor
Calibration Section......................................................................... 18
Deleted Figure 33 ........................................................................... 18

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 3 of 24
Changes to Figure 33 ......................................................................19
Moved Figure 26 to Figure 28 .......................................................19
Deleted Figure 36 ............................................................................19
Moved Low Power TIA0/TIA1 Gain Resistor Calibration
Section and Figure 36 .....................................................................20
Changes to Low Power TIA0/TIA1 Gain Resistor
Calibration Section .........................................................................20
Moved Figure 37 and Figure 38 ....................................................21
Changes to Mass Erasing a Device Not Responding to
SWD Commands Section ..............................................................22
2/2019—Revision 0: Initial Version

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 4 of 24
POWER CONFIGURATIONS
This section describes the four different options to power the
EVAL-ADuCM355QSPZ. The different power options include
the following:
 Power via a microUSB connector, P4, and the on-
board ADP7158 low dropout (LDO) regulator, which
is the default power option.
 Connect 3.3 V to the AVDD and DVDD connectors.
This setup is useful for measuring the current
consumption of the EVAL-ADuCM355QSPZ via the
current meter.
 Power via the 8-pin P27 debug header (a different
USB connection option to the PC).
 Power via an external 5 V supply to the 2-pin JP37
connector. Optionally, an external 5 V supply can
power the ADP7158 instead of the USB using this
setup.
MicroUSB DIRECT POWER VIA P4 AND ADP7158
LDO REGULATOR
To power the EVAL-ADuCM355QSPZ via the P4 microUSB
connector, take the following steps:
1. Ensure that the JP40 and JP42 to JP46 jumpers are
inserted. These jumpers control the features shown in
Table 1.
2. Remove the JP37 jumper.
Table 1. Jumper Connections
Jumper Description
JP45 and
JP46
Connect the UART pins from the ADuCM355 to the
UART to USB transceiver chip (U2) (see Figure 3).
JP40 Connects the 5 V USB supply to the LDO input (U3)
(see Figure 4).
JP42 Connects the 3.3 V LDO output to the EVAL-
ADuCM355QSPZ power supply filters (see Figure 4).
JP43 and
JP44
Connect the DVDD and AVDD rails to filters for the
DVDD and AVDD analog supplies to the ADuCM355
(see Figure 4).
16887-002
Figure 2. Direct Power via MicroUSB Cable

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 5 of 24
0.1µF
FT232RQ
M20-9990245
0.1µF 0.1µF
JP46
JP45
C38
C40
C37
U2
5VUSB
3V3VOUT
USBD+
USBD–
P0.10_SOUT
P0.11_SIN
3V3VOUT
3V3VOUT
12
12
119
14
15
30
26
2
32
3
18
28
27
29 25 23 13 12
5
20 17
4
PAD
31
6
7
8
9
11
10
21
22
24
16
VCCVCCIO
CBUS4
CBUS3
CBUS2
CBUS1
CBUS0
RTS
DTR
TXD
OSCO
3V3OUT
NCEP AGNDGND
USBDP
USBDM
CTS
DCD
DSR
RI
RXD
OSCI
TEST
RESET
DGND
DGND
DGND
DGND
DGND
16887-003
Figure 3. JP45 and JP46 Connect the ADuCM355 UART Pins to the USB Transceiver
ADP7158ACPZ-3.3-R7
560Ω
SML-310MTT86
10µF
60Ω
AT 100MHz
0.1µF
1µF
2.2Ω
60Ω
AT 100MHz
2.2Ω
0.1µF
0.1µF
10µF
0.1µF
1µF
0
1µF
10µF
JP36
DS1
R17
JP40
JP37
JP42 JP43
JP44
C57
C54
C55
E4
E3
R9
R8
C47
C41
JP6
C43 C44
U3
C42
C46
C45
AVDD_PREFILTER
DVDD
AVDD
5VUSB
DVDD_PREFILTER
AC
12
12
12
1212
12
12
12
12
8
3
2
1
10
9
6
7
PAD
5
4
DGND
DGND
AGND
DGND
DGND
EP
VIN
VIN
VREG
REF
REF_SENSE
EN
BYP
VOUT_SENSE
VOUT
VOUT
DGND
16887-004
Figure 4. Schematic Section with Key Jumpers Around LDO and Power Supply

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 6 of 24
DIRECT 3.3 V POWER VIA THE AVDD AND DVDD
CONNECTORS
To measure the ADuCM355 current consumption (IDD), connect
3.3 V directly to the AVDD and DVDD connectors.
To power the EVAL-ADuCM355QSPZ in this case, apply a
3.3 V supply directly to Pin 1 on the AVDD connector and to
Pin 1 on the DVDD connector.
Jumper Setup with Direct 3.3 V Connection
The jumper settings required when using a 3.3 V connection
are as follows:
1. Insert JP32, JP34, JP43, and JP44.
2. Remove JP42.
For additional information, see Figure 6.
POWER VIA USB FROM 8-PIN DEBUG
CONNECTOR (P27)
If using the older USB-SWD/UART and debug interface, the
ADuCM355 can also be powered from the USB. The UART to
USB interface is handled by the USB-SWD/UART-EMUZ board.
Jumper Setup with Power via USB
Close JP35, JP40, JP42, JP43, and JP44 when using power via
the USB (see Figure 5).
16887-006
Figure 5. Power via 8-Pin P27 Debug Connector
POWER VIA EXTERNAL 5 V SUPPLY TO 2-PIN
CONNECTOR (P37)
The last power supply option is to connect an external 5 V
supply to the 2-pin P37 connector. This 5 V supply is the input to
the ADP7158 LDO regulator that has a 3.3 V output voltage. Do
not connect the microUSB cable to P4. This option is a debug or
test option only.
16887-005
Figure 6. Power DVDD and AVDD Directly via Power Header Blocks

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 7 of 24
CONNECTING AN ELECTROCHEMICAL SENSOR
The ADuCM355 has two measurement channels (CH0 and CH1)
for electrochemical sensors. A 2-lead, 3-lead, or 4-lead sensor
can be connected to either CH0 or CH1. Figure 7 shows an
electrochemical sensor connected to CH1.
16887-007
Figure 7. Sensor Connector

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 8 of 24
GETTING STARTED WITH THE TOOL CHAIN
DOWNLOADING THE INTEGRATED
DEVELOPMENT ENVIRONMENT (IDE)
The ADUCM355 firmware examples use either the IAR
Embedded Workbench® or Keil μVision® IDEs to run the
firmware. Ensure that a full or evaluation version of either
software is downloaded and installed to run the example
applications. IAR Embedded Workbench supports the
ADUCM355 with Version 8.32.1 and later for ARM. Keil μVision
supports Version 5.28 and later.
INSTALLING THE ADuCM355 SUPPORT PACKAGE
The ADUCM355 firmware examples are source controlled on
www.GitHub.com. To clone the repository, execute the
following command of the Git command line:
git clone --
recursive https://github.com/analogdevicesin
c/aducm355-examples.git
This command downloads the main repository and the
submodules. If the code from the web browser downloads, the
examples/ad5940lib folder does not download automatically and
compilation errors occur. Download the code manually from
GitHub in the shared library file that contains the ADUCM355
examples and the AD5940 example. Both devices have the same
analog front end.
When using Keil μVision, the ADUCM355 device family pack
can be downloaded as part of a Cortex® microcontroller
software interface standard (CMSIS) pack. Download the pack
from GitHub.
The sample firmware contains the following folders:
 The common folder contains all library files common
to all applications.
 The examples folder contains specific example
projects. This folder is divided into the following three
subfolders:
 The AnalogDie folder contains example projects that
demonstrate how to use specific blocks on the analog die.
 The DigitalDie folder contains examples that
demonstrate how to use the digital die and peripherals
such as SPI or I2C.
 The ApplicationExamples folder contains application
level examples such as M355_ECSns_DualWE, which
demonstrates how to configure a dual working electrode
sensor and calculate gas parts per million (PPM)
readings.
 The inc folder contains files included for the
microprocessor.
RUNNING A GPIO EXAMPLE IN IAR EMBEDDED
WORKBENCH
The ADUCM355 CMSIS pack is not supported for IAR
Embedded Workbench. To use IAR Embedded Workbench,
clone the repository from the GitHub directory, as described in
the Installing the ADuCM355 Support Package section. To run
the general-purpose input/output (GPIO) example, navigate to
examples > DigitalDie > M355_GPIO > iar. Double click the
M355_GPIO.eww file to open the project in the IAR Embedded
Workbench (see Figure 8).
16887-008
Figure 8. M355_GPIO.eww File Location
Project Folder Structure
The IAR Embedded Workbench project folder structure is
shown to the left of the IAR Embedded Workbench window
(see Figure 9). The app folder contains files specific to the open
application. In Figure 9, M355_GPIO.c is the example shown.
The common folder contains the required library files for the
open application. For the GPIO example, the library files are
ad5940.c, ClkLib.c, DioLib.c, IntLib.c, and UrtLib.c. The
startup folder contains start-up files for the microprocessor, and
the Output folder contains the files that are autogenerated by
the IDE. All subsequent firmware examples follow this folder
structure in the IAR Embedded Workbench.

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 9 of 24
16887-009
Figure 9. IAR Embedded Workbench

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 10 of 24
Compiling and Running Firmware
To compile and run the ADuCM355 firmware, take the
following steps:
1. In the IAR Embedded Workbench window, navigate to
Project > Rebuild All (see Figure 10).
16887-010
Figure 10. Project > Rebuild All
2. Click Rebuild All. The IDE begins building the executable
from the source files, which may take a couple of seconds.
The message shown in Figure 11 appears in the Build window
when the build is complete.
16887-013
Figure 11. Build Output Window
3. To run the firmware on the ADuCM355, ensure that the
EVAL-ADuCM355QSPZ is powered on and the J-Link
debugger is connected to P3 on the EVAL-ADuCM355QSPZ,
then click Download and Debug to load the firmware to
the ADuCM355 and launch the debugger (see Figure 12).
Launching and downloading the debugger can take a few
seconds or more.
16887-011
Figure 12. Launching the Debugger
4. Open a terminal program such as RealTerm to view the
UART data from the ADuCM355 (see Figure 13). The
baud rate is 230,400 bps.
16887-113
Figure 13. UART Data in RealTerm
5. Figure 14 shows the debug interface. Click the blue arrow
(shown in the red circle) to begin code execution. The UART
prompts the user to press either the S2 or S3 button. The
DS2 LED toggles on and off with each button press.

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 11 of 24
16887-014
Figure 14. Debug Interface
RUNNING A GPIO EXAMPLE IN KEIL μVISION
To download the ADuCM355 device family pack for Keil μVision,
visit the Keil website and search for MDK5 software packs. Save
the .pack file to a directory on the PC. Double click the file to
install the pack.
16887-215
Figure 15. ADuCM355 Pack Installer
Follow the on screen instructions to unzip the contents from
the .pack file, and click Finish when complete. Open Keil μVision,
and open the pack installer, as shown in Figure 16.
16887-216
Figure 16. Opening Pack Installer in Keil μVision
On the left side of the pack installer window, click the Devices
tab and select the ADuCM355, as shown in Figure 17. On the
right side of the pack installer window, click the Examples tab
(see Figure 18). All supported example projects for the
ADuCM355 display as shown in Figure 18.

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 12 of 24
16887-217
Figure 17. Pack Installer Devices
16887-218
Figure 18. ADuCM355 Examples
Find the M355_GPIO (EVAL-ADuCM355QSPZ) example, and
then click the Copy button next to the example to copy the
example project into a local directory and launch the project in
Keil μVision. To compile and build the project, click the Rebuild
icon shown in the blue circle in Figure 19. To load the code
onto the ADuCM355, ensure that the EVAL-ADuCM355QSPZ
is powered on and the mIDAS-Link debugger is connected, and
then click the load icon shown in the red circle in Figure 19.
16887-219
Figure 19. Build and Load Project

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 13 of 24
APPLICATION EXAMPLES
This section describes how to use the ADuCM355 application
examples that are part of the ADuCM355 software development
kit (SDK). The ADuCM355 is a dual-die device that has a
Cortex-M3 digital die and an analog front-end (AFE) die. The
AFE die and the AD5940 are the same except for some differences
in which pins are bonded out, and both devices share a
common library interface to simplify firmware development.
The main library files in the SDK are AD5940.c and AD5940.h.
All functions in this library are compatible with the
ADuCM355, AD5940, and AD5941. All AFE related function
names begin with AD5940_. Some projects in the SDK have files
labeled AD5940Main.c, which contain the upper controllers that
control the AFE die and are mostly common between the
ADuCM355, AD5940, and AD5941.
The Cyclic Voltammetry Example section outlines how to use
the following example projects:
M355_ECSns_CycloVoltammetry
M355_ECSns_EIS
M355_ECSns_CappaTest
M355_ECSns_SingleWE
M355_ECSns_DualWE
M355_AfeWdt
CYCLIC VOLTAMMETRY EXAMPLE
Cyclic voltammetry is a common electrochemical measurement
in which the current on the sense electrode is measured in
response to a ramp like voltage applied on the reference electrode.
Figure 20 shows a typical, stepped differential voltage between
the reference and working electrodes of the sensor where V1 is
the initial voltage on the reference electrode and V2 is the peak
voltage on the reference electrode.
VOL
T
AGE
V
2
V
1
TIME
16887-015
Figure 20. Typical Cyclic Voltammetry Waveform
In the ADuCM355 firmware package, the M355_ECSns_
CycloVoltammetry project demonstrates how to implement a
cyclic voltammetry measurement on the ADuCM355. There are
two main files within the project, AD5940Main.c and Ramp.c.
The AD5940Main.c file contains the upper controllers that
control the high level application parameters. The Ramp.c file
contains the low level device configuration for the cyclic
voltammetry measurement.
Figure 21 shows the AD5940RampStructInit (void) function
defined in the AD5940Main.c file. Modify the main parameters
for the signal such as ramp start voltage, ramp peak voltage,
and ramp duration for this function within this file.
16887-221
Figure 21. Cyclic Voltammetry Parameters
To test the firmware, construct a dummy electrochemical cell
using 1 kΩ resistors in a star network (see Figure 22). Connect
each resistor network pin to the CE0, RE0, SE0, and DE0 pins
on the P5 header. Ensure that the configurations are constructed
as shown in Figure 22.
16887-016
Figure 22. Resistor Star Network Connected to P5 Header
To begin measuring and gathering data, open a terminal program
such as RealTerm. Configure the baud rate for 230,400 bps.
Compile and build the project in the preferred IDE and load
the code onto the ADuCM355. Run the measurement, and save
the data to a .csv file for processing. If the definition of
OPT_RAMP_MEAS (parameter defined in the Ramp.h file) is
set to 1,the following four measurements are performed:

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 14 of 24
Current through SE0.
Voltage on SE0.
Voltage on RE0.
Current through SE0 measured a second time.
To plot the current response of the test, open the saved .csv file in
Microsoft® Excel. Figure 23 shows the plotted response current.
–600
–500
–400
–300
–200
–100
100
0
200
300
500
400
600
1
17 33 49 65 81 97
113 129 145 161 177 305 193 209 225 241 257 273 289 321 337 353 369 385
CURRENT (µA)
INDEX
16887-017
Figure 23. Example SE0 Channel Current Measurement
EIS EXAMPLE
EIS is a common electrochemical measurement in which an ac
excitation signal is applied to an electrochemical cell. The response
current is measured, and the impedance is calculated.
On the ADuCM355, the EIS measurement is a three-step process.
The response current in each step is measured using a high
speed transimpedance amplifier (TIA).
The EIS measurement process is as follows:
1. A signal is applied across RCAL.
2. A signal is applied across RLOAD.
3. A signal is applied across ZSENSOR + RLOAD.
In each step of the measurement processes, the measured current is
input to the discrete Fourier transform (DFT) hardware accelerator
that calculates the complex number of the current measurement
and provides the real and imaginary parts. RCAL is a precision
resistor connected to the ADuCM355 RCAL0 and RCAL1 pins,
RLOAD is the internal load resistor on the SE0 path, and ZSENSOR is
the impedance under test.
Use the following equation to calculate the actual impedance:
ZSENSOR = (ZSENSOR + RLOAD)− ZRLOAD
where:
ZSENSOR + RLOAD is the impedance of RSENSOR and RLOAD measured
together as a single impedance.
ZRLOAD is the impedance of RLOAD.
Open the M355_ECSns_EIS example project in the preferred
IDE. For the purpose of this initial test, a dummy electrochemical
cell is used. Connect three 1 kΩ resistors in a star network, and
connect the star network to the CE0, RE0, and SE0 pins on P5
of the EVAL-ADuCM355QSPZ (see Figure 22).
In the AD5940Main.c file, there are several configurable
parameters that are shown in Figure 24. To couple the ac excitation
signal on top of a dc bias, set the SensorCH0.SensorBias parameter.
To apply a frequency sweep, modify the SweepCfg parameters.
16887-225
Figure 24. EIS Parameters
To run the impedance measurement, take the following steps:
1. Launch thedebugger in theIAR Embedded Workbench.
2. Open a terminal program with a 230,400 bps baud rate.
3. Execute the code.
4. A prompt to press the S2 switch is sent over the UART and
displays in the terminal. Press S2 to begin the impedance test.
5. When the impedance measurement completes, the results
are sent to the UART (see Figure 25). Save the results in a
Microsoft Excel file for further analysis, if necessary.
16887-019
Figure 25. Impedance Results
CHRONOAMPEROMETRY EXAMPLE
Chronoamperometry is an electrochemical technique in which
the voltage applied to an electrochemical cell is stepped. The
response current on the sense electrode is measured. Figure 26
and Figure 27 show typical chronoamperometric measurement
and sensor responses.

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 15 of 24
V
O
L
T
AGE
TIME
EXCITATION W
A
V
EFORM
16887-020
Figure 26. Typical Chronoamperometric Voltage Stimulus Waveform
CURRENT
TIME
RESPONSE
W
A
V
EFORM
16887-120
Figure 27. Typical Chronoamperometric Current Response Waveform
In the ADuCM355 firmware development package, the M355_
ECSns_CapaTest project implements a chronoamperometric
measurement.
The AD5940Main.c file contains an
AD5940AMPStructInit()function that modifies the main
measurement parameters.
For the following example, only CH0 is used and all default
values are used. The resistor star model is connected to P5, as
per the examples described in the Cyclic Voltammetry Example
section and the EIS Example section.
Load the project in the preferred IDE and open a terminal
program. Compile and build the project and load the code onto
the ADuCM355. Start the code execution and save the UART
data to a .csv file for processing.
The example code sends the following three arrays of results to
the UART at a 230,400 bps baud rate:
The first set of values includes the current
measurement results for the SE0 channel in μA.
The next set of values includes the voltage
measurement results for the SE0 channel in V.
The final set of values includes the voltage
measurement results for the RE0 channel in V.
–100
100
0
200
300
500
400
600
1
115 229 343 457 571 685 799 913
1027 1141 1255 1369 1483 1597 1711
CURRENT (µA)
INDEX
16887-122
Figure 28. Output Data Using the M355_ECSns_Capatest Example with
Three 1 kΩ Resistors
DC CURRENT EXAMPLE
The dc current is a standard electrochemical measurement.
Depending on the sensor type, a bias voltage is applied between
the reference and sense electrodes. The current output on the
sense electrode is measured.
In the ADuCM355 firmware package, the M355_ECSns_
SingleWE project implements a dc current measurement on
an electrochemical cell connected to CH0. The measurement
parameters can be configured in the AD5940AMPStructInit()
function in the AD5940Main.c file. For testing purposes, connect
the 1 kΩ resistor star network to P5. Set the Vzero firmware
parameter to 1100 mV, and set the SensorBias firmware
parameter to 500 mV to apply a 500 mV bias across the 1 kΩ
resistor network. Ensure that the EVAL-ADuCM355QSPZ is
powered on and that the debugger is connected to the PC. Then
open the project in the preferred IDE, and compile and run the
example application. Open a terminal program to view the
results. The output is the current measured through the SE0 pin
on P5 of the EVAL-ADuCM355QSPZ (see Figure 29).
16887-021
Figure 29. CH0 Output

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 16 of 24
4-LEAD ELECTROCHEMICAL SENSOR EXAMPLE
Many electrochemical sensors come in 4-lead packages that have a
counter, a reference, and two sensing electrodes. The ADuCM355
supports biasing and measuring of these sensor types.
The M355_ECSns_DualWE example project configures the
low power, potentiostat CH0 channel to bias the sensor. The
current flowing to and from the SE0 pin is measured via the
low power TIA Channel 0 (TIA0). The current flowing from
the SE1 electrode is measured via the low power TIA Channel 1
(TIA1).
The TIA amplifiers convert the current to a voltage that is
measured via the analog-to-digital converter (ADC), and the
source code calculates the current flowing in each electrode.
The M355_ECSns_DualWE code example project is located in
the examples folder.
Figure 30 shows the configurable parameters located in the
AD5940Main.c file. Modify the value of the correct
LpTiaRtiaSel parameter for each channel based on the
maximum expected current.
Figure 31 shows the connection details between the 4-lead
sensor and the ADuCM355.
16887-231
Figure 30. Dual Working Electrode Configuration
V
BIAS0
VBIAS
SW12
PA
ADC
MUX
LPTIA0
LPTIA1
SW0
SW14
SW2
SW3
RE0RE0
CE0
CE0
SE1
CAP_POT0
100nF
SW13
V
ZERO0
VZERO
VZERO
LPDAC0
VZERO TO LPTIA1+ INPUT
R
TIA
R
LOAD
R
F
AIN7_LPF1 AIN4_LPF0
16887-136
SE0
SE0
SE1
SW0
R
TIA
R
LOAD
R
F
Figure 31. Circuit Setup for 4-Lead, Dual Gas Detection Sensor

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 17 of 24
CONNECTING AN EXTERNAL GAIN RESISTOR
ACROSS THE HIGH SPEED TIA
The internal high speed TIA has a programmable gain resistor
that allows the user to either configure a high speed current
measurement channel for different input current ranges, or to
connect an external gain resistor instead.
The EVAL-ADuCM355QSPZ supports the connection of an
external transimpedance amplifier resistor (RTIA) across the
AIN0 pin and DE0 pin, which is labeled RTIA on the top side
of the printed circuit board (PCB).
The current flows from the AIN0 pin into the high speed TIA
inverting input with the HSTIA connected to the DE0 pin.
The ADC selects the HPTIA_P and HPTIA_N input channels to
measure the voltage drop across the external RTIA resistor (see
Figure 32).
When the user populates the external gain resistor, the gain
resistor can be used instead of the internal gain resistor. Figure 32
shows the external resistor connected to AIN0 and DE0. Note
that RLOAD_03 and RTIA2_03 are set to 0 Ω so as not to effect the
measurement.
The M355_ExternalRTIA code example project in the examples
folder demonstrates how to set up the high speed TIA for an
external gain resistor.
AIN0 T1
T10 HPTIA_N
HSTIA
EXTERNAL
R
CAL
DE0 R
TIA2_03
R
LOAD_03
1.11V REFERENCE
HPTIA_P
16887-030
Figure 32. ADuCM355 External RTIA Connection to the High Speed TIA
AFE DIE WATCHDOG TIMER EXAMPLE
The ADuCM355 supports a watchdog timer on the AFE die.
The watchdog timer clocks via an oscillator that is completely
independent of the clocks in the Cortex-M3 core. Therefore,
the watchdog timer meets the IEC 61508 requirement of an
independent watchdog timer for a microcontroller and eliminates
the need for an external watchdog timer chip.
The M355_AfeWdt code example project in the examples
folder shows how to configure the windowed watchdog mode.
The WDT_INTERRUPT_EN #define parameter configures the
project to generate either a reset or an interrupt.
The project uses a default timeout period of 16 sec. A minimum
waiting period of 4 sec is required before a watchdog refresh is
allowed. Refreshing the watchdog within 4 sec causes a reset or
interrupt to occur depending on the setting of Bit 1 of the
WDTCON register. If the timeout period elapses, a reset or
interrupt also occurs. To avoid a reset or interrupt generation,
refresh the watchdog timer within the minimum period of 4 sec
and the timeout period of 16 sec.
The watchdog timer refresh is triggered when the ASCII
Character 1 is sent from the PC.

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 18 of 24
ADUCM355 SYSTEM CALIBRATION
Because of the complexity of the ADuCM355 and the large
number of voltage and current measurement channels on the
device, many calibration routines are implemented to ensure a
high level of measurement accuracy. This section describes the
main calibration functions with links to further online
information.
HIGH SPEED TIA GAIN RESISTOR CALIBRATION
The high speed TIA has three different programmable gain
resistor options.
Adjust the gain resistors to convert the current from the SE0, SE1,
and DE0 inputs or from the DE1 input to a differential voltage
across the RTIA2 resistor, RTIA2_03 resistor, or RTIA2_05 resistor.
The RTIA2, RTIA2_03, and RTIA2_05 resistors have an initial accuracy
range and vary with temperature, as specified in the ADuCM355
data sheet where RTIA2 is the HPTIA RTIA gain resistor on the
SE0 and SE1 inputs, and RTIA_02 and RTIA_05 correspond to the
HPTIA RTIA gain on the DE0 and DE1 inputs.
If the high speed TIA is uncalibrated for the selected gain resistor
and the ADC programmable gain amplifier (PGA) setting, an error
is present when measuring an absolute input current.
To generate a precision calibration current, use the high speed
DAC to create a differential voltage across an external precision
RCAL resistor that is connected to the ADuCM355 RCAL0 pin
and RCAL1 pin. The precision calibration current can be
routed through any of the three high speed TIA gain resistors.
Because the calibration current value is known and the ADC
can measure the voltage drop across the RTIA2, RTIA2_03, and RTIA2_05
resistors, the exact RTIA resistor value can be determined.
Figure 33 to Figure 35 show the setup and switch settings that
connect the high speed DAC output to the external RCAL
resistor so that the current flows into the high speed TIA and
RTIA2, RTIA2_03, and RTIA2_05 gain resistors, respectively.
The AD5940.c file has a function that calibrates each gain
resistor for the HSTIA. For further details on how to use this
function, visit https://wiki.analog.com/resources/eval/user-
guides/eval-ad5940/calibration_routines/hstia_cal?doc=EVAL-
ADuCM355QSPZ-UG-1308.PDF.

EVAL-ADuCM355QSPZ Evaluation Board UG-1308
Rev. A | Page 19 of 24
HSDAC
ADC
INPUT
MUX
P
N
PGA ADC
RCAL0
PR0
DR0
NR1
TR1
T9
CALIBRATION
CURRENT
P_NODE
EXCITATION
AMPLIFIER
EXTERNAL
R
CAL
N_NODE
RCAL1
HPTIA_N
R
TIA2
1.11V (HSTIACON[1:0] = 00b]
HPTIA_P
P_NODE
N_NODE
HPTIA_P
HPTIA_N
16887-023
Figure 33. High Speed DAC, High Speed TIA, and Switch Matrix Settings for RTIA2 Calibration
HSDAC
P
N
PGA ADC
RCAL0
PR0
DR0
NR1
TR1
CALIBRATION
CURRENT
P_NODE
EXCITATION
AMPLIFIER
EXTERNAL
R
CAL
N_NODE
RCAL1
DE0
HPTIA_N
R
TIA2_03
R
LOAD_03
1.11V (HSTIACON[1:0] = 00b]
HPTIA_P
P_NODE
N_NODE
HPTIA_P
HPTIA_N
T6
T10
16887-024
ADC
INPUT
MUX
Figure 34. High Speed DAC, High Speed TIA, and Switch Matrix Settings for RTIA2_03 Calibration
PR0
HSDAC
P
N
PGA ADC
RCAL0 DR0
NR1
TR1
CALIBRATION
CURRENT
P_NODE
EXCITATION
AMPLIFIER
EXTERNAL
R
CAL
N_NODE
RCAL1
DE1
HPTIA_N
R
TIA2_05
R
LOAD_05
1.11V (HSTIACON[1:0] = 00b]
HPTIA_P
P_NODE
N_NODE
HPTIA_P
HPTIA_N
T8
T10
16887-025
ADC
INPUT
MUX
Figure 35. High Speed DAC, High Speed TIA, and Switch Matrix Settings for RTIA2_05 Calibration

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 20 of 24
LOW POWER TIA0/TIA1 GAIN RESISTOR
CALIBRATION
The ADuCM355 contains two independent, low power
TIA channels.
Each TIA has an independent, programmable gain resistor to
scale the input current from the SE0 pin and the SE1 pin to a
voltage that the ADC can measure.
Figure 36 shows the gain resistor for the low power TIA0. A
similar diagram is valid to use for the low power TIA1.
Similar to the example described in the High Speed TIA Gain
Resistor Calibration section, adjust the gain resistor to convert
the current from the SE0 input pin and the SE1 input pin to a
differential voltage across the RTIA resistors.
These resistors have an initial accuracy range and vary with
temperature, as specified in the ADuCM355 data sheet.
When these resistors are uncalibrated, an error is present when
measuring an absolute input current.
To generate a precision calibration current, use the low power
DAC to create a differential voltage across an external precision
RCAL resistor that is connected to the ADuCM355 RCAL0 pin
and RCAL1 pin. The precision calibration current is routed
through either the low power TIA0 gain resistor or the low
power TIA1 gain resistor.
Because the calibration current value is known and the ADC
can measure the voltage drop across each RTIA resistor, the exact
RTIA resistor value can be determined.
Figure 37 and Figure 38 show the setup and switch settings
used to connect the low power DAC outputs to the external
RCAL resistor so that the current flows into the LPTIAx gain
resistors, LPRTIAx.
Several example projects in the ADuCM355 SDK implement a
function to calibrate the gain resistor. For further details on
how to use this function, visit
https://wiki.analog.com/resources/eval/user-guides/eval-
ad5940/calibration_routines/lptia_cal?doc=EVAL-
ADuCM355QSPZ-UG-1308.PDF.
V
BIAS0
SW12
SW6
PA
SW9 LPTIA0_P_LPF0
ADC
MUX
SW7
LPTIA
FORCE/SENSE
SW0
SW1
LPTIACON0
[12:10]
LPTIACON0
[9:5]
PROGRAMMABLE
GAIN RESISTOR
SW2
SW8 SW14
SW15
SW4
RE0
SW10
SW3
SW11
10kΩ 10kΩ
RE0
SW5
CE0
CAP_POT0
SE0
RC0_0
RC0_1
SW13
V
ZERO0
V
REF2V5
LPDAC0
ULPBUF
ULPREF
TO
CHANNEL 1
A
IN4/LPF0
R
LPF
ULPTIACON0
[15:13]
R
TIA
R
LOAD
16887-027
Figure 36. LPTIA0 Gain Calibration Resistor