ST STEVAL-FSM01M1 User manual

Introduction
STEVAL-FSM01M1 is an industrial dual channel digital I/O board for safe automation. It provides a powerful test platform for
deep technical evaluation of ST’s smart power ICs for factory automation and functional safety.
The PCB provides a digital interface compatible with STM32 Nucleo boards which is galvanically isolated from the power side
of the board using digital signal isolators including STISO621. The process side I/O section is based on a dual channel digital
input current limiter CLT03-2Q3 and Intelligent Power Switches IPS160HF and IPS161HF. These core ICs are accompanied
with many other industrial-grade ST ICs which play the critical role in providing all the needed auxiliary functions like DC voltage
supply management (L7983, LDK220), onboard runtime condition monitoring ADC (ADC120) and other safety features and
protections.
STEVAL-FSM01M1 (PCB, board or module in the following text) provides a high-level of flexibility and testing options thanks to
a multi-level redundancy of its overall implementation. For example, the system protection scheme can be flexibly adapted in
several ways by simply modifying the assembly configuration of onboard components. This allows R&D engineers to optimize
and finetune design of the final product according to their exact application requirements already during the prototyping phase of
development.
The board can be operated either as a standalone evaluation testbed or it can be connected in combination with an STM32
Nucleo board to provide a complete evaluation ecosystem. An associated firmware package STSW-FSM01 (available at
www.st.com) provides routines to operate all functions of the PCB, plus it supports a simple user command interface allowing to
control the board interactively from PC. This firmware package for STM32 is compatible with NUCLEO-F401RE however, it can
be adapted to run on any other STM32 Nucleo platform.
Figure 1. STEVAL-FSM01M1
Getting started with STEVAL-FSM01M1 safe digital I/O test board
UM3175
User manual
UM3175 - Rev 1 - May 2023
For further information contact your local STMicroelectronics sales office. www.st.com

1Architecture
1.1 Basic characteristics & features
• Design with advanced robustness and safety
• Flexible topology for agile electrical testing of onboard ICs
• Operating range: 8V to 30V (optionally to 60V)
• 2 digital outputs with current rating 2A (OUT1) resp. 0.5A (OUT2)
• 2 digital inputs compatible with IEC 61131-2 Type 1 and 3
• Output section based on IPS160HF and IPS161HF:
– Single-channel Intelligent Power Switch (IPS) for safe automation
– Operating voltage range up to 60V
– Low-power dissipation (RDS(on) = 60 mΩ)
– Output current capability 2A (IPS160HF) and 0.5A (IPS161HF)
– Fast power-up performance for safe automation
– Integrated overcurrent/overtemperature protection and diagnostics
– Fast demagnetization of inductive loads
• Input section based on CLT03-2Q3
– Self-powered dual channel digital input current limiter
– Operating voltage range up to 60V
– Integrated Test Pulse feature allowing self-integrity verification of the IC
• Additional key onboard ICs:
–STISO621 – 100Mbps dual channel signal digital isolator
–L7983, LDK220 – 60V step-down regulator and low noise LDO
–ADC120 – 8-channel 12-bit/1Msps analog-digital convertor with SPI
–STL42P6LLF6 – 60V STripFET F6 Power MOSFET
–SMC30J, SM6T and SM2T3V3A TVS protections
• Embedded redundancy including cascade high-side switch topology
• Runtime control of all IC features (Cut-off limitation and Test-Pulse generation)
• Onboard ADC allows real-time system monitoring and integrity verification
• Status and diagnostic LEDs for each I/O channel
• Two onboard LEDs for user defined indication
• Onboard 1kVRMS galvanic isolation
• Active supply voltage reverse polarity protection
• Compatible with STM32 Nucleo development boards
• Associated firmware package STSW-FSM01 for NUCLEO-F401RE providing all routines for application
programming and command access from PC (through USB)
• Certification and compliance
– CE certified
– RoHS
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Architecture
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1.2 Description
STEVAL-FSM01M1 is a safe dual channel digital I/O expansion board compatible with STM32 Nucleo. Its
system architecture reflects our long-term experience with designing digital I/O applications to reach the highest-
grade robustness and to meet the requirements on reliability of operation in the most challenging industrial
environments such as Factory Automation and Functional Safety.
While majority of standard Nucleo expansion shields are usually plugged-in on top of an STM32 Nucleo board
using the ARDUINO® Uno V3 connectors the STEVAL-FSM01M1, in contrary, provides the base for the Nucleo
board that is connected on top of it by means of its onboard ST morpho extension headers. Hence the
microcontroller pins and peripherals handling the operation of the STEVAL-FSM01M1 are physically separated
from those utilized by other X-NUCLEO boards eventually connected to the system. This way additional
expansion shields can be easily added on top of the stack to extend system functionality while minimizing
possible overlap of utilized microcontroller resources.
The associated STM32 firmware package STSW-FSM01 is compatible with NUCLEO-F401RE however, it can be
easily adapted to run on any other STM32 Nucleo platform.
In further sections of this document we describe functionality of the particular subsystems and features of the
PCB in general. For complete information and detailed understanding of its implementation (schematics, BOM,
layout etc.) please refer also to the documentation freely available on the webpage of the PCB and to the
datasheet specifications of onboard ICs.
1.3 System structure
As a digital I/O board, the STEVAL-FSM01M1 translates low voltage logic level I/O signals (3.3V) provided on its
digital interface and transmits them onto 0/+24V binary signals on its galvanically isolated power domain called
process side.
The PCB can be used either as a standalone testboard with its logic signals provided by a user-specific hardware
(custom host microcontroller board, laboratory test equipment etc.), or it can be plugged together with the
NUCLEO-F401RE and operated from PC utilizing its associated firmware package STSW-FSM01.
Block diagram of the board is shown in Figure 2. It consists of the following main hardware components:
1. Digital interface and galvanic isolation
2. Process side - digital input section
3. Process side - digital output section
4. Power management and supply voltage protection
5. System control and condition monitoring
Figure 2. STEVAL-FSM01M1 block diagram
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Description
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1.3.1 Digital interface and galvanic isolation
All electrical features of STEVAL-FSM01M1 are accessible through its digital interface provided by STM32 Nucleo
compatible onboard ST morpho extension headers CN7 and CN10. These two connectors bring access to the two
onboard user LEDs as well as to the complete functionality on the galvanically isolated process side. Pin mapping
of control signals to the digital interface connectors is illustrated in Figure 3. The digital side is supplied through
the pin ‘3V3’ located on the connector CN7 and any ‘GND’ pin available at CN7 resp. CN10 connectors. The
maximum admissible supply voltage for the digital side is 5V.
In order to decouple sensitive high-speed logic ICs from the power chips exposed to the harsh environment on
process side of the I/O module, the digital interface connectors are galvanically isolated using a set of digital
signal isolators including the 100 Mbps dual channel isolator STISO621.
Figure 3. Digital interface connector pin mapping
1.3.2 Process side
1.3.2.1 Process interface connector
Process side PCB terminal CN1 represents the power supply and digital I/O interface of the board. Its layout
is shown in Figure 4. From the left to the right this connector provides connection of IN1 and IN2 digital input
channels followed by outputs OUT1 (0.5A) and OUT2 (2A). Power supply connector is highlighted using a
differentiated terminal colours. Orange terminal represents connection of positive supply (+24V) and the blue one
represents the GND terminal. Blue terminal (GND) is doubled in order to provide an additional access point for
connecting sensors/actuators and for laboratory test purposes. The last slot (PE, green) represents the earth
connection terminal which is capacitively coupled to both positive and negative power supply lines of the PCB
using high voltage 4.7nF capacitors.
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System structure
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Figure 4. Process interface connector and testpoints
To allow easy system function testing and laboratory measurements the STEVAL-FSM01M1 contains a set of
onboard testpoints which provide measuring access to all the key voltage nodes in the system (power supply
voltage, logic section supply and digital I/O status and diagnostics). These testpoints are also shown in Figure 4.
1.3.2.2 Digital input section
Two independent digital inputs compatible with Type 1 and 3 (ref. IEC 61131-2) are realized using the industry
proven self-powered digital input current limiter CLT03-2Q3. This device integrates two galvanically isolated chips
each of them implementing one digital input channel efficiently translating the process side voltage signals (0V
or 24V) to the logic levels. CLT03-2Q3 further provides a native test-pulse generator which allows IC integrity
verification during runtime. This feature can be actively controlled through the PCB’s digital interface.
1.3.2.3 Digital output section
The output section contains an advanced protection scheme including loss of VCC (resp. GND) protection,
parasitic reverse polarity protection and external demagnetization bypass circuit to boost the system immunity
against any potential electrical overstress. Assembly pattern of the protection components can be widely modified
by the user in order to emulate various custom application scenarios.
Each digital output channel is comprised of a combination of a P-channel MOSFET power switch STL42P6LFF6
in series with a single-channel high-side switch IPS160HF (resp. IPS161HF) providing safety redundancy in each
channel. This is a common topology used in safe automation output systems. First channel (OUT1) is rated for
0.5A nominal loads while the second channel (OUT2) has its nominal current 2A. Apart from the different current
limitation level (resp. current limitation level setting) the two IPS ICs are identical.
IPS16xHF IC’s include a cut-off limitation function which allows significant power dissipation savings in case of
overload. This feature can be also actively controlled through the digital interface.
1.3.2.4 Power management and supply voltage protection
The onboard circuits are supplied from the +24V and GND terminals on the connector CN1. Power supply path is
protected against surge and transient overvolage events by means of filtering low-ESR capacitors and Transient
Voltage Supressor (TVS). Reverse polarity protection is realized based on a 60V P-channel StripFET F6 power
MOSFET ST42P6LLF6 present in positive power supply path (VCC). Logic circuits supply (+3.3V) is derived from
the VCC through a cascade of a step-down switching regulator L7983 (producing onboard VDC 4V) followed by a
low noise linear regulator LDK220.
1.3.2.5 System control and condition monitoring
Each output channel has its own diagnostic signal indicating thermal overstress of the front-end IPS. Diagnostic
signals are propagated to the isolated digital interface.
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System structure
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In addition to the diagnostic function integrated in the IPS16xHF drivers the STEVAL-FSM01 has an onboard
1Msps 12bit A/D converter ADC120 allowing continuous monitoring of operating conditions in all the key system
nodes like VCC voltage, safety P-channel MOSFET outputs (VCC1, VCC2) as well as the channel output voltages
(OUT1, OUT2). This data is accessible during runtime via SPI. Furthermore, voltage nodes in each output
channel that are subject to voltage monitoring (VCCx and OUTx) are accompanied with actively controlled pull-
down resistor circuits for line voltage discharge in order to allow a defined system function verification.
Distribution of integrated circuits on the PCB is illustrated in Figure 5. Complete schematics of the PCB as well as
all the other associated documentation and firmware is available on the STEVAL-FSM01M1 dedicated webpage
at st.com. In the following sections we will describe the particular function blocks and their application more in
detail.
Figure 5. PCB components distribution
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2Application
The main purpose of industrial digital I/Os is interfacing with binary sensors and actuators in environments
like factory automation, home & building automation technology and many other application segments like
transportation infrastructure, agriculture machines or automatic PoS systems. Digital I/Os play the key role on the
technological background. Digital I/O application is illustrated on the example of Programmable Logic Controller
(PLC) operating in a smart factory (Figure 6).
Figure 6. Digital I/Os in factory automation
By the term Sensor we can imagine either a simple switch, a button or a smart digital sensing device like a
pressure or temperature sensor, light curtains etc. Actuators are typically devices like valves, lamps or relays
which perform physical actions in the automated environment.
In addition to the standard industrial I/O applications, this evaluation board is specifically designed to meet also
the advanced technical requirements of Safety-critical automation. Therefore it implements additional specific
features ensuring robustness, redundancy and advanced diagnostics.
This evaluation board is primarily intended for use during evaluation and prototyping phase of an application
design to speed-up and simplify development of real industrial systems. It can be connected with actuators and
electrical test loads (resistive, inductive or capacitive) or sensor devices with type 1 and 3 according to IEC
61131-2.
2.1 User controllable IC features
In this section we list and briefly describe all controllable functions of the PCB which can be accessed through the
digital interface (Figure 3).
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Application
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2.1.1 User LEDs
The PCB features two onboard LEDs D12 and D13 located on the digital side (see Figure 7) which are available
for any user-specific indication purpose. The green LED (D12) is contacted to the pin PC2 and the red LED D13 is
contacted to PC3, both located on connector CN7.
Figure 7. Onboard user LEDs D12, D13
2.1.2 I/O section control signals
Below we list the logic signals associated with operation of digital I/O’s in particular. In addition to the elementary
control signals, there are signals allowing to actively control special features of the I/O ICs. The same set of
signals is available for each of the two input (resp. output) channels. Therefore, in order to simplify the notation
and to avoid duplication, in the below lists we don’t specify the channel identification number (‘1’ or ‘2’) and
instead we substitude it with ‘x’. Direction of signals (seen from the microcontroller perspective) is marked in
brackets by ‘R’ (read, input signal) or ‘W’ (write, control signal) together with the feature pin mapping for channel 1
and 2 (separated by ‘ / ’).
Digital inputs
1. OUTPx: input signal reflecting the binary status of digital input INx [R; PC0 / PH1]
2. TPx: control signal enabling function of integrated test pulse generator
(ref. datasheet of CLT03-2Q3) [W, PA15 / PB7]
Digital outputs
1. OUTx_CTRL: Control signal for digital output OUTx [W, PB8 / PA11]
2. OUTx_DSC: Activation of OUTx line discharge pull-down resistor [W, PC10 / PC9]
3. OUTx_DIAG: OUTx IPS diagnostic pin [R, PC12 / PC6]
4. COFFx: Cut-off limitation feature control on OUTx IPS [W, PD2 / PC5]
5. VCCx_CTRL: Control of safety MOSFET switch providing supply voltage for OUTx IPS
[W, PA12 / PB9]
6. VCCx_DSC: Activation of VCCx line discharge pull-down resistor [W, PC8 / PC11]
Onboard voltage monitoring
8-channel A/D converter ADC120 is used for monitoring voltages in all key nodes of the system, namely: VCC,
VCCx and OUTx.
This ADC is accessible through SPI available at the following pins of connector CN10:
1. /CS: Chip Select [W, PB12]
2. SCLK: SPI clock signal [W, PB13]
3. DIN: SPI MOSI signal [W, PB15]
4. DOUT: SPI MISO signal [R, PB14]
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User controllable IC features
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3Getting started
In this section we will describe how to easily setup the basic hardware configuration allowing to operate the PCB
in combination with NUCLEO-F401RE and its associated firmware package STSW-FSM01.
We focus mainly on the description of hardware part of the system in this documet. All needed information related
to software part of the system is available at st.com in a dedicated documentation (UM3176) of STSW-FSM01.
3.1 Hardware components
The following hardware components are required:
1. STM32 Nucleo board NUCLEO-F401RE
2. USB cable (type A to Mini-B USB) to connect the STM32 Nucleo and PC
3. +24V DC power supply with connection wires to supply the
STEVAL-FSM01M1 expansion board
4. Windows PC
3.2 Process side connector operation
CN1 terminal allows connecting all process side components (sensors, actuators, and supply wiring) in a quick
and easy way. You can plug a counductor by simply pushing it as shown inFigure 8.
Figure 8. CN1 conductor connection
Disconnection of a conductor is also easy by gently pressing the corresponding terminal slot using a screwdriver
and then pulling the conductor out according to Figure 9.
Figure 9. CN1 conductor connection
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3.3 System setup and connection
In order to ensure correct operation of the evaluation system please verify that the Nucleo board is in correct
hardware configuration as follows (default HW setup):
• JP5 on U5V for firmware flashing
• JP1 open
• JP6 closed
• CN2 : closed 1-2, 3-4
• CN3 open
• CN4 open
• CN11 open
• CN12 open
Nucleo board shall be flashed with the code available in the firmware package STSW-FSM01. Nucleo board
programming can be done either by downloading a binary file into the microcontroller flash memory using the
STM32CubeProg, or it can be carried out using an IDE (e.g. STM32CubeIDE). All the above-mentioned tools can
be found and downloaded at www.st.com.
Now with all components collected and set correctly the system can be plugged together as shown in Figure 10.
Figure 10. STEVAL-FSM01M1 system setup
If the above evaluation setup is correctly connected and supplied, it indicates presence of process side VCC
voltage by a red LED D11 as also highlighted in Figure 10 and it’s time to play the program.
Note: Rated voltage to supply the board is +24V, however, the onboard firmware is configured to operate in range of
VCC from 21.6V. Lower supply voltage will be detected by the system monitoring routines as undervoltage and in
such case the PCB operation is automatically disabled.
3.4 Program functionality
After power-up or reset of the digital side (Nucleo), the onboard firmware performs an initialization routines
and verifies functionality of the system by toggling onboard LEDs and digital outputs. This procedure takes
around 5 seconds and its runtime is indicated by a green LED LD2 located on the Nucleo board. When PCB
initialization procedure finishes successfully, the LD2 is blicking continuously and the red user LED D13 is off. If
the inicialization doesn’t finish succesfully (e.g. due to undervoltage), this is indicated by the D13 continuously on.
Digital outputs can now be toggled simultaneously using a blue button and signal presence on the digital inputs
is indicated by toggling the user LEDs D12 (IN1) and D13 (IN2). Further functions can be examined utilizing a
command access from PC via USB as described in UM3176.
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