ST PCC020V1 User manual

Introduction
The STEVAL-PCC020V1 USB to I²C/UART board interfaces a Windows®-based PC with STNRG digital power supply
controllers such as STNRG011.
It is basically a bidirectional bridge between USB and I²C/UART buses and embeds an on-board power supply to communicate
and program the STNRG IC without need of mains.
The associated GUI allows monitoring the status of the digital controller in real-time and tuning specific parameters according to
customers' needs.
Figure 1. STEVAL-PCC020V1 interface board
Getting started with the STEVAL-PCC020V1: USB to I²C UART interface board
and associated GUI for STNRG products
UM2342
User manual
UM2342 - Rev 1 - February 2018
For further information contact your local STMicroelectronics sales office.
www.st.com/

1 Interface board aim
Figure 2. Customer typical application shows a customer typical application based on STNRG011 for the power
supply section.
The host microcontroller receives information only from the STNRG011 using an opto-isolated connection:
STNRG011 transmits metering information (instantaneous power) continuously, and the black box content at
reset.
Hence, the host microcontroller does not have access to the STNRG011 optional E²PROM where the patch and
black box history are stored.
Figure 2. Customer typical application
Figure 3. STNRG011 in demo/debug configuration shows the STNRG011 on the STEVAL-PCC020V1 interface
board or during debug configuration.
In the latter case, you can access the external optional E²PROM using the I²C protocol to program the associated
patches and reset the black box content.
You also have to access STNRG011 using UART bidirectional communication to:
• program the STNRG011 NVM content to change specific parameters according to customers’ needs
• display the system specific parameters in real-time to check its behavior during the debug and integration
phases.
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Interface board aim
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Figure 3. STNRG011 in demo/debug configuration
To minimize STRGN011 pin count, UART and I²C interfaces share the same pins. The interfaces are not isolated
from the mains as they are located on the offline converter primary side.
Important: This adapter board is exclusively designed to interface with STNRG011 products.
In the final customer application, the tasks performed by the interface would be handled directly by the host
microcontroller or the application processor.
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Interface board aim
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2 Getting started
2.1 STEVAL-PCC020V1 interface board overview
The STEVAL-PCC020V1 interface board key features are:
• Bidirectional communication between PC (USB) and STNRG011
• Self-powered from the USB line
• On-board 19 V generation for STNRG011 programming
• Electric Isolation between USB and other board electronics
• I²C bus running at up to 1 MHz
• A UART bus running at 19200 bps
• UART and I²C bus muxed together on the same interface
• On-board firmware upgrade through USB port
• Display power metrics (AC voltage, PFC power)
• Access to STNRG M24C32 optional E²PROM (used to store patch, calibration and event history data)
• Program NVM settings
• RoHS compliant
2.2 GUI overview
The GUI key features are:
•Runs on Windows XP, Windows 7 (.NET 4.0 framework needed)
• Real-time monitoring of the digital controller status
• Access to STNRG011 NVM parameters
• Access to STNRG011 external E²PROM for patch upload, calibration and event history
• Embedded PFC calibration wizard
2.3 Package contents
The STEVAL-PCC020V1 package includes:
• Hardware
– the interface board
– a 1.8 m USB A to USB mini-B cable
– a 15 cm 6-wire flat cable for target connection to the STNRG011 device
• Software
– USB drivers
– PC GUI installation package
Note: The complete software package is available at www.st.com.
2.4 System requirements
To use the STEVAL-PCC020V1 interface board, you need a PC with Windows® operating system.
The graphical user interface (GUI) works with Microsoft Windows XP or later versions and .NET Framework 4.0.
Note: The .NET Framework 4.0 is not included in the Windows XP installation package.
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3 Hardware description and setup
3.1 Block diagram
Figure 4. STEVAL-PCC020V1 block diagram
3.2 Galvanic isolation
The STNRG011 has to be placed on the offline converter primary side: the galvanic isolation between the USB
and the remaining electronic of the board prevents any voltage from reaching the host PC and causing electrical
damage or interference.
3.3 Power supply
The STEVAL-PCC020V1 interface board is self-supplied via the 5 V USB connector.
This voltage directly supplies U3 and the related circuitry.
A dual isolated DC-DC module (U5) is used to supply the remaining part of the board, maintaining the isolation
among the PC and the target sides.
U5 generates two supplies, loosely regulated (+5 V and +20 V).
3.3.1 MCU subsystem supply (5 V)
The +5 V supply is later converted to a stable and clean +3V3 thanks to the linear regulator U6, which is always
on.
3.3.2 VCC generation (20 V)
The +20 V is always generated from +5 V and +15 V cascaded together (VOUT2- is referenced to VOUT1+ in
place of ground).
This voltage is later on supplied by the linear regulator U8 which has the following roles:
•to generate a stable +18.5 V;
• to act as a switch; U8 is enabled thanks to the MCU GPIO PA14 configured in open drain mode. When the
MCU wants to enable the VCC generation, PA14 is driven low.
D5 provides an OR-ing diode which, by default, is short-circuited by R17 resistor (0 W).
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3.3.2.1 VCC soft start
At VCC generation switch on, VCC is typically decoupled by a 100 to 200 µF capacitor on the STNRG011 device.
If the regulator is switched on abruptly, an inrush current is generated that cannot be sustained by the upfront DC-
DC converter, which then enters current limitation.
Since the +20 V is generated by cascading +5 V and 15 V, the current limitation also impacts the +5 V supply
(hence the MCU).
When the MCU supply drops below the PowerOnReset threshold, the MCU resets and the board reboots.
To avoid this behavior, the linear regulator U8 is switched on via a soft start using a PWM enable signal (which
limits the current on the upfront DC-DC).
When VCC has reached a stable value (that is, the VCC capacitor is charged), the enable signal remains in the
steady-state condition (always on, so always low).
Soft start phase usually lasts about 120 ms.
Figure 5. VCC ramp-up typical waveform
3.3.2.2 NVM programming
The STEVAL-PCC020V1 interface board provides a VCC voltage to the target device that is high enough for an
NVM programming operation.
STNRG011 programming requirements are +18 V and 35 mA max. current.
If the VCC on the target device is < 17 V, the programming VCC can be simply connected to the target VCC
through a couple of OR-ing diodes.
The 19 V supply current delivered is limited to 100 mA by the on-board LDO (U8).
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Power supply
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3.4 USB bridge
The communication between the STEVAL-PCC020V1 and the PC is managed by the latter as a standard serial
peripheral; the IC U3 converts the USB connection into a virtual COM port (refer to the electrical schematic).
By default, the virtual COM port operates at 921600 bps.
A yellow LED near the mini-B USB connector turns on when the CP2102 has been recognized (enumerated) by
the host operating system.
The VCP RX and TX signals are then isolated thanks to the opto-couplers U1 and U2 and connected to the
STM32F3 (U9) microcontroller USART1.
Important: The USB port and the remaining part of the board are isolated from the mains.
The microcontroller performs:
•Conversion between the host UART and I²C protocols
–The I²C speed can rise up to 1 MHz (maximum speed allowed by the STNRG011).
– The STM32F3 allows bidirectional communication between the PC and the target device through the
UART to I²C conversion.
•Conversion between the host UART and the STNRG011 UART .
This is mainly baud rate matching: STNRG011 operates at 19200 bps, whereas the host UART operates at
921600 bps.
Note: The microcontroller also manages the muxing of the UART and I²C protocols on the same interface.
3.5 VCC monitoring
The MCU also monitors the STNRG011 VCC line voltage.
STNRG011 VCC is sampled periodically by the MCU via a simple resistive bridge divider plus a low-pass filter
using R20, R21 and C19. The divider ratio is 10/78=1/7.8.
The divided voltage is then sent to STM32F3 PA0 pin on a regular 12-bit ADC.
For instance, this allows preventing the use of the on-board VCC when the STNRG011 is already operating.
Note: This feature accuracy is ±100 mV.
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USB bridge
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4 Using the board
4.1 Board connectors, LEDs and buttons
Figure 6. STEVAL-PCC020V1 interface board connectors
Figure 7. STEVAL-PCC020V1 interface board status LEDs
Table 1. STEVAL-PCC020V1 LEDs (ON, OFF, blinking state)
D1 D2 D3 D4
ON OFF ON Blinking ON Blinking ON OFF
VCP
recognized by
the PC
VCP not
recognized/
inactive
Normal
operation
Firmware
error
Waiting for
the
STNRG011
frames
Receiving
STNRG011
frames
Internal VCC
enabled
Internal VCC
disabled
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4.2 How to connect the STEVAL-PCC020V1 interface board to the offline converter
Figure 8. STEVAL-PCC020V1 interface board typical connection
Procedure Step 1. Connect the STEVAL-PCC020V1 interface board to a PC via a USB cable
Step 2. Connect the interface board and the offline converter board together through the 6-wire flat cable
Step 3. Connect the offline converter to the load
Step 4. Connect the mains
Caution:
You should never plug or unplug the interface board while the connection is running (for example, when the offline converter is
running). If the 5 V UART signals and +15 V VCC (typ.) are connected when the GND is not yet connected, the STNRG011 or
the interface board might be damaged.
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How to connect the STEVAL-PCC020V1 interface board to the offline converter
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5 Software installation
You have to install the USB driver and the PC GUI before using the STEVAL-PCC020V1 interface board.
5.1 Virtual COM port driver installation (SiLabs CP2102)
To use the STEVAL-PCC020V1 interface board, first install one of the USB drivers located in the CD folder Driver
\CP210x_VCP_Windows:
• CP210xCVCPInstaller_x86.exe (for 32-bit OS)
• CP210xCVCPInstaller_x64.exe (for 64-bit OS)
Alternatively, you can find the latest version of the drivers at SiLabs.
When the interface board is plugged to the PC, the driver is automatically installed.
5.2 GUI installation
Procedure Step 1. Launch HVDPS-STNRG011-Setup.msi
Step 2. Follow the installation wizard instructions.
By default, the GUI is installed under C:\Program Files (x86)\STMicroelectronics\STNRG011 GUI\.
The GUI installer creates an icon in the Start menu, under STMicroelectronics\STNRG011.
Figure 9. HV-DPS GUI icon
Note: If a previous version of the software has already been installed, it must be uninstalled through the Windows
Control Panel Uninstall option.
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