Analog Devices EVAL-ADuCM355QSPZ User Manual

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 14 of 24
 Current through SE0.
 Voltage o
n SE0.
 Voltage on RE0
.
 Curren
t through SE0 measured a second
time.
T
o 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
Fi
gure 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 R
CAL
.
2. A sig
nal is applied across R
LOAD
.
3. A sig
nal is applied across Z
SENSOR
+ R
LOAD
.
In each ste
p 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. R
CAL
is a precision
resistor connected to the ADuCM355 RCAL0 and RCAL1 pins,
R
LOAD
is the internal load resistor on the SE0 path, and Z
SENSOR
is
the impedance under test.
Use the following equation to calculate the actual impedance:
Z
SENSOR
= (Z
SENSOR
+ R
LOAD
)− Z
RLOAD
where:
Z
SENSOR
+ R
LOAD
is the impedance of R
SENSOR
and R
LOAD
measured
together as a single impedance.
Z
RLOAD
is the impedance of R
LOAD
.
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 the debugger in the IAR 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
Fi
gure 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.

Analog Devices EVAL-ADuCM355QSPZ Specifications

General

Category	Evaluation Board
Part Number	EVAL-ADuCM355QSPZ
Microcontroller	ADuCM355
Embedded	Yes
Operating Temperature Range	-40°C to +85°C
Compatible Devices	ADuCM355
Manufacturer	Analog Devices Inc.
Function	Evaluation Board
Purpose	Evaluation of the ADuCM355
Interface	USB, UART

Summary

EVALUATION BOARD FEATURES

ADuCM355 Debug and Programming

Debug and programming capabilities of the ADuCM355 microcontroller.

Electrochemical Sensor Evaluation

Evaluate performance with electrochemical gas sensors.

Temperature Sensor (ADT7420)

±0.25°C accurate temperature sensor via I²C.

MicroUSB Power and PC Connection

MicroUSB power option and PC connection for the evaluation board.

EQUIPMENT NEEDED

PC Requirements

PC running Windows® 7 or later.

Sensor Connection

Connect an electrochemical gas sensor or resistor star network.

DOCUMENTS NEEDED

ADuCM355 Hardware Reference Manual

Official hardware reference manual for the ADuCM355.

ADuCM355 Data Sheet

Comprehensive data sheet for the ADuCM355 microcontroller.

SOFTWARE NEEDED

Development IDEs

IAR Embedded Workbench or Keil µVision IDEs.

ADuCM355 GitHub Repository

Access firmware examples and code from GitHub.

Terminal Program

Terminal program such as RealTerm for viewing output.

GENERAL DESCRIPTION

ADuCM355 System Overview

ADuCM355 system for biasing and measuring electrochemical sensors.

Evaluation Board Purpose

EVAL-ADuCM355QSPZ allows evaluation of ADuCM355 performance.

Consult ADuCM355 Data Sheet

Consult ADuCM355 data sheet in conjunction with user guide.

POWER CONFIGURATIONS

MicroUSB Direct Power

Powering the board via the microUSB connector and on-board LDO.

3.3V Power via AVDD/DVDD

Connecting 3.3 V to AVDD and DVDD connectors for current measurement.

POWER VIA USB FROM 8-PIN DEBUG CONNECTOR (P27)

Jumper Setup for Debug Header USB Power

Jumper settings for powering via the 8-pin debug connector USB.

POWER VIA EXTERNAL 5V SUPPLY TO 2-PIN CONNECTOR (P37)

External 5V Power Setup

Connecting an external 5 V supply to the P37 connector.

CONNECTING AN ELECTROCHEMICAL SENSOR

Sensor Channels (CHO and CH1)

ADuCM355 has two measurement channels for electrochemical sensors.

Sensor Connection Types

2-lead, 3-lead, or 4-lead sensors can be connected to CH0 or CH1.

GETTING STARTED WITH THE TOOL CHAIN

Downloading Development Environment (IDE)

Download and install IAR Embedded Workbench or Keil µVision.

Installing ADuCM355 Support Package

Clone the ADuCM355 examples repository from GitHub.

RUNNING A GPIO EXAMPLE IN IAR EMBEDDED WORKBENCH

Project Folder Structure (IAR)

Structure of the IAR Embedded Workbench project folder.

COMPILING AND RUNNING FIRMWARE

Rebuild All Project

Compile the firmware by rebuilding all project files in the IDE.

Launching the Debugger

Load the compiled firmware onto the ADuCM355 and launch the debugger.

Viewing UART Data

Open a terminal program to view UART data from the ADuCM355.

RUNNING A GPIO EXAMPLE IN KEIL µVISION

Installing ADuCM355 Keil Pack

Download and install the ADuCM355 device family pack for Keil µVision.

Opening Pack Installer

Open the Keil pack installer to access device and example projects.

RUNNING A GPIO EXAMPLE IN KEIL µVISION (continued)

Copying and Building GPIO Project

Copy the M355_GPIO example project and build it in Keil µVision.

Loading GPIO Project onto ADuCM355

Load the GPIO example project onto the ADuCM355 using the mIDAS-Link debugger.

APPLICATION EXAMPLES

ADuCM355 SDK Overview

Overview of ADuCM355 SDK, including Cortex-M3 and AFE die.

Main Library Files (AD5940.c/h)

Main library files AD5940.c and AD5940.h for firmware development.

Example Projects List

List of example projects including Cyclic Voltammetry, EIS, etc.

CYCLIC VOLTAMMETRY EXAMPLE

Cyclic Voltammetry Measurement

Measure current response to ramp voltage on reference electrode.

AD5940RampStructInit Function

Modifying parameters for ramp voltage, peak voltage, and duration.

Test Cell Setup

Construct a dummy electrochemical cell using 1 kΩ resistors.

EIS EXAMPLE

EIS Measurement Process

Three-step process to measure response current to AC excitation.

Impedance Calculation Equation

Equation to calculate actual impedance using measured values.

EIS Parameters Configuration

Configuring parameters like LpTiaRf, LpTiaRl, and SensorBias in AD5940Main.c.

Running the EIS Measurement

Steps to launch debugger, open terminal, and start impedance test.

CHRONOAMPEROMETRY EXAMPLE

Chronoamperometry Measurement

Measure response current when voltage is stepped on electrochemical cell.

CHRONOAMPEROMETRY EXAMPLE (continued)

M355_ECSns_CapaTest Project

Project implementing chronoamperometric measurement.

AD5940AMPStructInit Function

Modifying measurement parameters for chronoamperometry.

Data Output Format

Results sent to UART including current, voltage measurements.

DC CURRENT EXAMPLE

DC Current Measurement

Measuring current output on the sense electrode with applied bias voltage.

M355_ECSns_SingleWE Project

Project implementing DC current measurement on a single electrode.

Test Setup and Configuration

Connecting 1 kΩ resistor, setting Vzero and SensorBias parameters.

4-LEAD ELECTROCHEMICAL SENSOR EXAMPLE

ADuCM355 Support for 4-Lead Sensors

ADuCM355 supports biasing and measuring 4-lead sensors.

M355_ECSns_DualWE Project

Project configures CH0 for bias and measures current via TIA0/TIA1.

Dual Working Electrode Configuration

Configuring parameters for dual working electrode measurement.

CONNECTING AN EXTERNAL GAIN RESISTOR ACROSS THE HIGH SPEED TIA

High Speed TIA Gain Resistor Options

Programmable gain resistor for high speed current measurement.

External Gain Resistor Connection

Connecting external RTIA resistor across AINO and DE0 pins.

M355_ExternalRTIA Example Project

Example project for setting up high speed TIA with external gain resistor.

AFE DIE WATCHDOG TIMER EXAMPLE

ADuCM355 AFE Watchdog Timer

Watchdog timer on AFE die, independent of Cortex-M3 core.

Windowed Watchdog Mode

Configuring the windowed watchdog mode using M355_AfeWdt project.

Watchdog Refresh Trigger

Watchdog refresh triggered by ASCII Character 1 from PC.

ADuCM355 SYSTEM CALIBRATION

Calibration Routines Importance

Calibration routines ensure high level of measurement accuracy.

HIGH SPEED TIA GAIN RESISTOR CALIBRATION

Gain Resistor Options

Three programmable gain resistor options for the high speed TIA.

Calibration Process Overview

Using high speed DAC and RCAL resistor for calibration.

Determining RTIA Resistor Value

Determining exact RTIA resistor value using known calibration current.

LOW POWER TIA0/TIA1 GAIN RESISTOR CALIBRATION

Low Power TIA Gain Resistors

Independent programmable gain resistor for low power TIA channels.

Calibration Current Generation

Using low power DAC to create calibration current across RCAL resistor.

LPTIA Gain Calibration Example

Project implementing function to calibrate gain resistor for LPTIA.

MASS ERASING A DEVICE NOT RESPONDING TO SWD COMMANDS

Recovering Locked Devices

Recovering devices locked during debug sessions or resets.

Mass Erase Procedure

Steps to mass erase user flash using S3 button and IAR IDE.

ORDERING INFORMATION

BILL OF MATERIALS