ST STDES-BLUEPLUG2 User manual

Introduction
The STDES-BLUEPLUG2 is a reference design for home-automation and Internet of Things (IoT) applications.
The on-board BLUENRG-M2SP is compliant with Bluetooth Low Energy (BLE) specification 5.2 to allow secure communication
of metering data from specific electrical loads to a smart phone with BLE support.
It supports multiple roles simultaneously and can act at the same time as Bluetooth smart master and slave device.
The device current consumption on AC mains is 3 to 7 mA.
The device acts as BLE peripheral device which can be connected to any smart device using the Android ST BLE PLUG app
(available for free download on Google Play) to control and monitor the load and its energy parameters.
The app features load ON/OFF turning, scheduling, dimming and metering parameters.
The STDES-BLUEPLUG2 embeds an STPM32 metering chip for high accuracy measurement of power and energy in power
line systems using shunt current sensors, a three-terminal TRIAC which controls the current through AC switching for various
electrical system applications, and a non-isolated buck converter supply based on the VIPER06XS. This type of supply is ideal
for the applications (like ST BLE PLUG) where a large amount of current is not needed and a small form factor is required.
The STDES-BLUEPLUG2 is a fully assembled board developed for performance evaluation only, not available for sale.
Figure 1. STDES-BLUEPLUG2 reference design - top and bottom views
How to use the STDES-BLUEPLUG2 reference design for home automation
smart plugs
UM2862
User manual
UM2862 - Rev 2 - May 2021
For further information contact your local STMicroelectronics sales office.
www.st.com

1Safety information
FCC notices
Note: ST reference designs and evaluation boards are intended to help and facilitate development of products. Using
a direct copy of any of them does not waive the requirement for testing and certification of products mandated by
governing agencies and authorities.
This device compiles with part 15 of the FCC Rules. Operation is subject to the following two conditions:
1. This device may not cause harmful interference
2. This device must accept any interference received, including interference that may cause undesired
operation.
Electrical safety
Danger:
Due to the high voltage present on the non-isolated components, special care must be taken to
avoid the risk of electric shocks and burns.
There are no protections against accidental human contact with high voltage components.
Never touch live board components when the board is connected or immediately after the board is
disconnected, as the capacitors may still be charged.
Do not connect probes to any high voltage components if the board is not isolated from the mains
supply, as this may cause damage to equipment.
1. The board must be used only by qualified persons.
2. De-energize the board and all its interface outputs and electrical loads before performing any electrical or
diagnostic operations.
3. Only program and debug the board with the isolated JTAG in-circuit debugger/programmer to avoid
damaging the tools.
4. Use a mains insulation transformer when you perform any tests with spectrum analyzers or oscilloscopes.
Note: STMicroelectronics assumes no responsibility for accidents or injury caused by improper use of this
development tool.
Personal safety
1. Wear personal protective equipment such as latex gloves or safety glasses with side shields, or protect the
EVM in an adequate lucent plastic box with interlocks from accidental touch.
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Safety information
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2Overview
2.1 Features
• Smart Energy Meter design with wireless connectivity
• BLE (Bluetooth Low Energy) v5.2 connectivity to:
– control (turning ON/OFF)
– display metering parameters
• NFC interface: to configure the design and store the logs
• Dimming of light for TRIAC dimmable load rated below 12 A
• Rated voltage: 240/120 VAC (typ.)
• Rated current: 12 A (typ.)
• Power consumption of plug: 0.7 W (max.)
• Instantaneous and averaged power
• RMS and instantaneous voltage and current
•BLUENRG-M2SP module radio certifications:
– FCC certification: S9NBNRGM2SP
– IC certification: 8976C-BNRGM2SP
2.2 Typical applications
• Control and monitoring of energy parameters using BLE.
• Smart metering
• Home automation
• Smart lighting
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Overview
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2.3 Board architecture
Figure 2. STDES-BLUELUG2 featured components
3
2
1
5
4
6
1. BTA12-800BWRG (12 A TRIAC)
2. STPM32TR (IC for metering applications)
3. BLUENRG-M2SP (Bluetooth Low Energy v5.2 module)
4. VIPER06XS (30 KHz offline converter)
5. STTH110RL (High voltage ultra-fast rectifier)
6. L4931 (very low drop voltage regulator)
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Board architecture
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Figure 3. STDES-BLUEPLUG2 block diagram
The mains supply and loads are monitored by the STPM32TR standard metering IC, while the BLUENRG-M2SP
Bluetooth Low Energy module handles data and command interfacing for the ST BLE PLUG Android app
developed for the board, and can store data via the EEPROM connector.
The 12 A TRIAC acts as a switch for the load and phase controller for dimming.
The supplies for the ICs are regulated from the VIPER06XS buck converter output.
The board includes a manual switch to turn the load on and off, and LEDs to signal connectivity status.
2.4 Zero crossing detector circuit
A zero crossing circuit is an electrical circuit that begins operation with the AC load voltage at close to 0 V in the
AC cycle. Zero crossing detection is used for the dimming reference point to fire the TRIAC accordingly.
The circuit has three resistors connected to phase of the AC line to lower the resultant voltage and a resistor on
the base of a PNP transistor which acts as a pull up resistor: when the voltage at the base drops below the base
operating voltage, the transistor switches to output LOW.
Figure 4. Zero crossing detector circuit
PHASE
3V3
DIO6_ZCR
Q3
2STR2160
R51
10K-0402
R53
10K-0402
R54
270K-1206
R37
270K-1206
R52
270K-1206
GND
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Zero crossing detector circuit
UM2862 - Rev 2 page 5/25

The purpose of the circuit in our design is to start the TRIAC conducting very near the moment when the load
voltage crosses zero volts (at the beginning or the middle of each AC cycle represented by a sine wave), so that
the output voltage can be modified by changing the firing angle of TRIAC, which in turn will change the required
output waveform.
Figure 5. Zero crossing detection with oscilloscope
3
2
1
Note: 1. AC voltage
2. Output of the transistor
3. Output of the transistor goes low as ac voltage approaches zero
Figure 6. AC at 50% phase
2
1
Note: 1. AC voltage
2. TRIAC Output at 50% duty cycle
2.5 Power supply
For power supply, a non-isolated Buck converter using the VIPER06XS offline converter is used, with PWM
operation at 30 kHz and frequency jittering for lower EMI. Standby power is very low, at < 30 mW.
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Power supply
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This type of supply is ideal for the ST BLE PLUG application, where large currents are not required, but a small
form factor is necessary.
Figure 7. Non-isolated buck converter
Test points - J10 & J13
NEUTRAL
PHASE
3V3
GND
C17
2.2uF-0402,50V
C45
27nF-0805,25V
D2
STTH110RL
R11
82K-0402
D4
STTH110RL
RV1
MOV
+
C34
1.5uF,400V
12
+
C36
1.5uF,400V
12
C49
200nF-0805
R32
7.5K-0805
R34
5.1K-0805
D1
SMA
C44
1.5uF-0805 25V
J1
CON2
1
2
R10
160k-0402
J13
N_IN
1
R1
10E-2410,1W
J10
P_IN
1
L1
470uH
U6
VIPER 06XS
1GND
2VDD
8
DRAIN3
9
DRAIN4
10
DRAIN
3LIM 4FB 5COMP
7
DRAIN2
6
DRAIN1
U2
L4931
1VOUT
2GND1
3GND2
4NC 5
INHIBIT
6
GND4
7
GND3
8
VIN
+
C46
330uF
12
L6
1mH
1 2
C18
100nF-0402,16V
NEUTRAL
PHASE
5V
5V
GND
GND
GND
GND
5V
The output of supply is set to 4.3 V, which is further regulated by the L4931 LDO to 3.3 V and 500 mA, to power
all the analog and digital sections.
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Power supply
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3Set up the board and connect with the Android app
Warning:
Before performing this task, please review all the safety procedures and precautions associated
with high voltage electrical circuits, and prepare the necessary protection equipment.
Use the procedure below to set up the board.
Step 1. On the evaluation board, connect the input mains and output load connectors.
Input mains connectors:
– P_IN (J10)
– N_IN (J13)
Load connectors:
– P_OUT (J11)
– N_OUT (J12)
Figure 8. Phase (P) and neutral (N) input (IN) and output (OUT) connectors
3
2
1
5
4
6
P_IN P_OUT N_OUT N_IN
J10 J11 J12 J13
Step 2. After powering up the board, RED LED (LD3) will indicate that the board is turned ON.
Step 3. Install the ST BLE PLUG 2.0 from Google Play store.
Figure 9. ST BLE PLUG launch screen
Step 4. Search for the device on your smart phone by selecting the [Scan BLE Devices] icon.
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Set up the board and connect with the Android app
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Step 5. Connect the devices to the App by selecting the STDES-BLUEPLUG2 device.
Figure 10. Connect the devices
Once connected with the board, the BLUE LED (LD2) will blink at the frequency of 2 Hz.
3.1 Control a load with the device
Follow the instructions below to control a load with the STDES-BLUEPLUG2 reference design and the ST BLE
PLUG app.
Step 1. Connect the board to a mains supply and a load, such as a light bulb.
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Control a load with the device
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Step 2. Select the load type ([Bulb] for this example).
Figure 11. ST BLE PLUG - load type panel
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Control a load with the device
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