ST STEVAL-USBC2DP User manual

Introduction
The STEVAL-USBC2DP adapter is a miniaturized solution with a USB Type-C plug and a DisplayPort receptacle that
implements the DisplayPort Alternate Mode of the USB Type-C and Power Delivery specifications for compatibility with the
VESA® Standard. The adapter allows you to extend the screen laptop equipped with a USB Type-C-interface onto any screen
with a DisplayPort interface. This mode enables computers, tablets, smartphones, displays and docking stations with the USB
Type-C connector to rout high-resolution A/V and USB data and power through a USB Type-C cable.
The STEVAL-USBC2DP is based on the high performance ARM® 32-bit Cortex®-M0 STM32F072 MCU running the X-CUBE-
USB-PD certified software that negotiates the Alternate Mode for DisplayPort with USB Power Delivery (PD) Vendor Defined
Messages (VDM). An optimized discrete analog front end (AFE) and the embedded STM32 peripherals allow management of
the Type-C plug lines and USB PD communication. The integrated USB 2.0 controller and the ST USB 2.0 Middleware stack
running on the STM32 provide the Billboard Device Class support required by the USB Power Delivery standard, as well as the
device firmware upgrade (DFU) capability
X-CUBE-USB-PD is compliant with the USB Type-C™ 1.3 and USB Power Delivery 2.0 and 3.0 specifications.
Figure 1. STEVAL-USBC2DP evaluation board
STEVAL-USBC2DP USB Type-C™ to DisplayPort™ adapter
UM2355
User manual
UM2355 - Rev 2 - March 2018
For further information contact your local STMicroelectronics sales office.
www.st.com

1STEVAL-USBC2DP system architecture
The STEVAL-USBC2DP is a full reference design that implements DisplayPort Alternate Mode over the USB
Type-C and Power Delivery protocol. It is a highly compact solution with a USB Type-C plug and a DisplayPort
receptacle on the same board, without any USB Type-C extension cables.
Figure 2. the STEVAL-USBC2DP board functional blocks
The reference design is based on the following functional blocks:
1. an STM32F072 microcontroller that runs the X-CUBE-USB-PD software
2. a USB Type-C discrete analog front-end PHY
3. an on-board power management stage based on the LDK220 to supply the dongle through VBUS or
VCONN on the Type-C plug
4. an STG3684A high-speed switch that connects the DP auxiliary (AUX) signals with the SBU lanes.
UM2355
STEVAL-USBC2DP system architecture
UM2355 - Rev 2 page 2/20

1.1 USB Type-C to DisplayPort reference design architecture
The STEVAL-USBC2DP reference design for the USB Type-C to VESA DisplayPort adapter is a complete
solution based on the following logical blocks:
1. A USB Type-C reversible connector
2. A DisplayPort connector
3. An STM32F072 MCU running the X-CUBE-USB-PD software package with Middleware stack
4. A USB Type-C discrete analog front end
5. The on-board power management stage controlled by the LDK220 low dropout voltage regulator to supply
the dongle through the Type-C connector VBUS or VCONN pins
6. The STG3684A low voltage 0.5 Ω max. dual SPDT switch between the DisplayPort auxiliary (AUX) and the
side-band unit (SBU) lines
Figure 3. STEVAL-USBC2DP system architecture block diagram
The adapter reference design also features:
•Dual supply options through USB Type-C connector:
– VBUS
– VCONN
• VBUS voltage sensing for power monitoring
• USB 2.0 interface available on Type-C™ port for Billboard Device Class and Device Firmware Upgrade
• A power status LED and USB Power Delivery Status LED
• A RESET button
• On-board SWD connector that can be connected with the ST-LINK/V2-1 debugger/programmer embedded
on STM32 Nucleo boards
1.2 STM32F072 USB Type-C to DP controller
The STM32F072 microcontroller incorporates the high-performance ARM®Cortex®-M0 32-bit RISC core operating
at up to 48 MHz frequency, high-speed embedded memories (up to 128 Kbytes of Flash memory and 16 Kbytes
of SRAM), and an extensive range of enhanced peripherals and I/Os.
The microcontroller offers standard communication interfaces (two I2Cs, two SPI/I2S and four USARTs), a USB
Full-speed device (crystal-less), a CAN, a 12-bit ADC, a 12-bit DAC with two channels, seven 16-bit timers, a 32-
bit timer and an advanced-control PWM timer.
The microcontroller can operate in the -40 to +85 °C and -40 to +105 °C temperature ranges, from a 2.0 to 3.6 V
power supply.
A comprehensive set of power-saving modes allows the design of low-power applications.
UM2355
USB Type-C to DisplayPort reference design architecture
UM2355 - Rev 2 page 3/20

Figure 4. STM32F072 series microcontroller block diagram
In this USB Type-C to DP adapter implementation, the STM32F072 microcontroller manages the ST USB Power
Delivery FW library, which allows PD message transmission through the CC line.
The microcontroller also checks the VBUS provided by the source device and identifies the device attachment
and detachment events.
Additionally, the microcontroller manages the interrupt on the hot plug detection signal driven (DP_HPD) by the
monitor when it is connected.
UM2355
STM32F072 USB Type-C to DP controller
UM2355 - Rev 2 page 4/20

Figure 5. STM32F072 microcontroller schematic
VDD2
STL6N2VH5
5.1k
ESDALC5-1BF4
R7
PIN2
3
PA1
1
17
USART_TX
2
PB8
TP3
DP_AUX_P
40
5001
1
2
R19
R5
75
2
PB10
1
6
R6
27
Q2
J1
1
D13
R4
5
GND
PA7
11
PA2
2
C5
D_VDD
0.22µF
nRESET
GND
C6
VDD2
39
PB4
31
PA11 32
CLOCK_IN
CLOCK_OUT
19
VDDIO VDD1
DP_AUX_N
47
VDD1
34
23
2
USART_RX
LED BLUE
SWCLK
PB6
42
PB14
R9
GND
D_VDD
BOOT0
1
CC_RX
CC_TX
2
GND
15
PA6 16 DP_AUX_P
2
12
PB7
43
2
2
0.1µF
PB12
10k
1
VBUS
Boot
Option
Reset
Button
Ext.
Comm.
Conn.
5001
48
R16
38
PB3
Q1
1
2
DP_HPD
3
SWDIO PA13_SWDIO
VSS2
24
DP_AUX_N
RXREF
28
C22
1
R14
2
2
U4
2
8
TP2
35
PB9
0.0
1
6
PA14_SWCLK
PA15
10000pF
1M
1
PC14-OSC32_IN
4
10k
EXT_3.3V
R1
PB15
PA3 13
USART_RX
CC
1VBAT
D_VDD
1
GND
1
1PIN1
nRESET
SWDIO
820pF
STL6N2VH5
3
1
3
7
GND
PB2
20
1
2
nRESET
2
46
VSS3
SBU_ENABLE
1
2
VBAT VDDA
100
1
PB5
41
PA4
2
0.0
1
D3
PB13 26
5
75
1
36 VDDIO2
37
18
PB1
NRST
8VSSA
2
PIN3
4
1
6
5
1
2
DP_HPD
SW1
4
4.7k
45
1
1
PF0-OSC_IN
6
C7
24k
EXP_PAD
TP1
8.2k
22
8
8
4
25 21
BOOT0
14
PA5
PA12 33
USART_TX
GND
D_VDD
P2
PIN4
5PIN5
9
USB_DM
USB_DP
2
4
SWCLK
D_VDD
1
PA8
GND
R21
PC15-OSC32_OUT
5
29
PA9
49
7
R8
VSS1
R22
2
BOOT0
44
VDD_A
GND
7
3
PB0 1
5001
STM32F072C8U6
2PC13
169
1
PB11
PIN1
2
R3
1
PA0 10
7
PF1-OSC_OUT
VDDA
GND
1437566-3
P1
2
GND
D_VDD
GND
1.5K
2
R2
30
PA10
PIN2
SWD
Conn.
PD_HPD
1.3 USB Type-C plug and DisplayPort receptacle
As the board is a consumer with the Dead Battery Mode feature, the host USB Type-C connector must supply
power through the VBUS or VCONN pins of the CN1 connector.
UM2355
USB Type-C plug and DisplayPort receptacle
UM2355 - Rev 2 page 5/20

Figure 6. USB Type-C plug (CN1) schematic
DP_ML2+
A10
RX2+
2
VCONN
USB_DM
USB_DP
A8
A9
VBUS2
D2
C1
DP_ML2-
0.1µF
C3
B12
Wurth 632712000011
RX1+
R18
1k
B10 A3
A4
0.1µF
2
1
VConn
B5
VBUS3
GND
1
CN1
1
A1
TX1+ A2
VBUS
D1
ESDAULC5-1BF4
B9 VBUS4
SBU2
B8
DP_ML1+
1
1
0.1µF
VCONN
TX2+
D-1
ESDAULC5-1BF4
CC
DP_ML1-
GND
A5
D+1 A6
GND
2
GND4
2 1
GND
B2
GND3
TX1-
B11
RX1-
1
SBU2
A7
SBU1
0.1uF
2
DP_ML3+
C2
GND
B4
TX2-
B3 RX2- A11
GND2 A12
DP_ML0+
C4
VBUS
VBUS1
CC
B1
GND1
VBUS
2
VBUS
DP_ML0-
DP_ML3-
SBU1
2
The other CN1 pins for the high speed data paths (TX1+, TX1-; RX1+, RX1-; TX2+, TX2-; RX2+, RX2-) are
directly connected to corresponding DisplayPort main link channels (ML0+, ML0-; ML1+, ML1-; ML2+, ML2-;
ML3+, ML3) on the DisplayPort CN2 connector.
Figure 7. DisplayPort receptacle (CN2) schematic
2
DP_AUX_N
DP_AUX_P
20
GND
DP_ML3-
DP_ML0+
2
DP_ML0-
2
13
CONFIG1
R11
1M
R13
1M
ESDALC5-1BF4
GND
R10
GND
4.7M
1
ML2+ 5
GND3 4
ML2-
ESDALC5-1BF4
ML0+
0472720001
AUX_CH_P
GND5 16
2
DP_HPD
DP_ML3+
D4
ML1+ 8
19
DP_PWR_RET
HPD 18
2
DP_PWR
2
1
14
CONFIG2
GND1 11
15
CFG1
GND
1M
3
ML3+
1
DP_ML1+
1
CFG2
17
AUX_CH_N
ML1- 6
2
DP_ML1-
R15
2
GND2 7
10
9
2
1
D6
R12
ESDALC5-1BF4
D5
DP_ML2+
CN2
DP_ML2-
GND4 1
ML3-
1
12
ML0-
1
1
470k
The DisplayPort Auxiliary signals (DP_AUX_P and DP_AUX_N) are connected to SideBand Use pins SBU1 and
SBU2 through the STG3684A high-speed switch driven by the STM32F072.
UM2355
USB Type-C plug and DisplayPort receptacle
UM2355 - Rev 2 page 6/20

Figure 8. High Speed Switch for AUX/SBU management
10
2
Vcc 3
D8
8GND
100K
GND
D2 5
GND GND
2S1
7
1
STG3684AUTR
21S1
GND
1
ESDALC5-1BF4
D1
2
ESDALC5-1BF4
D_VDD
GND
R17
C8
1
D7
2IN
4
SBU_ENABLE
U2
1S2
1
62S2
2
DP_AUX_P SBU1
SBU2
1
2
91IN
0.22µF
DP_AUX_N
The USB Type-C to DP controller (STM32F072 microcontroller) receives hot plug detection signal (DP_HPD) from
the display through the CN2 connector.
1.4 Local power management stage and LEDs
As the adapter shall have the sink role and start up under Dead Battery Mode, the local power management stage
supplies the board through an LDK220 voltage regulator from the VBUS or VCONN voltage supply lines on the
host USB receptacle.
The LDK220 low quiescent current and low noise LDO supplies a maximum 200 mA output from a 2.5 V to 13.2 V
input range, with a typical drop-out voltage of 100 mV.
The STEVAL-USBC2DP platform includes the following status LEDs:
1. green LED D12 to signal that the platform is powered.
2. blue LED D13 (connected to the STM32F072 PA7 pin) to signal the status of the Alternative Mode operation.
Figure 9. schematic view of the local power management stage
C15
C18
1
GND
C10
GND
IN
1
LDK220M33R
VDD1
D10
STPS0520Z
VDD_A
VBUS
EN
3
2
3.3V
75
1
2GND
C19
2
C20
1
ESDA7P60-1U1M
2
C16
10000pF
R20
C21
GND
2
30Ohm@100MHz
1
GND
VDDIO
C11
1
3
GRPB031VWVN-RC
10000pF
2
1
VDDA
EXT_3.3V
4.7uF
2
1
3.3V
D9
0.1uF
1uF
2
1
0.1uF
LED YELLOW-GREEN
1
C12
D12
LED
Power-On
C9
GND
2
D_VDD
GND
C17
VCONN
1uF
1
1
D11
2
STPS0522 0Z
2
30Ohm@100MHz
GND
OUT 5
3.3V
1
1
0.1uF
2
C14
NC
4
1
J2
1
VDD2
VBAT
2
GND
2
10000pF
1
1
VDD_A
U3
0.1uF0.47uF
2
L2
2
4.7uF
1
0.1uF
2
1
D_VDD
2
GND
L1
C13
21
D_VDD
2
D_VDD D_VDD
Jumper J2 should remain on pins 2-3 for normal operation with VBUS or VCONN supplied through the host USB
Type-C connector. J2 can alternatively be closed on pins 1-2 to supply the platform through the STLINK SWD
connector during debugging.
UM2355
Local power management stage and LEDs
UM2355 - Rev 2 page 7/20

1.5 Reset button, connectors and jumper settings
Figure 10. Reset button, connector and jumper schematics
1
C5
1
Reset
Button
10000pF
10k
R1
nRESET
2
SW1
D_VDD
GND
1437566-3
2
DP_AUX_P
J1
1
5
GND
DP_AUX_N
2
Ext.
Comm.
Conn.
6USART_RX
3
DP_HPD
4
8
USART_TX
7
D_VDD
2
R4
GND
10k
1
Boot
Option
2D_VDD
1PIN1
2
100
1
BOOT0
R3
P1
PIN2
PIN2
3
1
nRESET
SWCLK
EXT_3.3V
SWDIO PIN3
4
P2
PIN4
5PIN5
PIN1
2
GND
SWD
Conn.
Note:
1.6
1.6.1
Connector J1 allows you to monitor DisplayPort Connector CN2 hot plug detection (DP_HPD) signals and
Auxiliary (DP_AUX_P and DP_AUX_N) signals, and includes a USART serial communication interface.
P2 allows you to program the microcontroller through an SWD connector (strip-line, not mounted) instead of DFU,
and provides access to all the microcontroller debugging features.
To facilitate programming, install a five-position header 0.100" (2.54 mm) through-hole connector on P2. Then,
connect the P2 SWD pins (2, 3 and 4) to the equivalent ones of the ST-LINK CN4 connector of an STM32
Nucleo-64 board, and connect P2 pin 1 to ST-LINK JP1 pin 1. Remove both jumpers on the ST-LINK CN2
connector to allow correct SWD operation (refer to UM1724 on www.st.com for more information).
P1 sets the microcontroller in DFU mode when it is closed with a jumper, so you can update application firmware.
STSW-USBC2DP software package
Description
The STSW-USBC2DP software package is designed to support the STEVAL-USBC2DP USB Type-C to
DisplayPort adapter evaluation board.
It contains the application firmware in binary file and .dfu formats, and allows the STEVAL-USBC2DP evaluation
board to adopt DisplayPort Alternate Mode operation according to the USB Type-C and Power Delivery
specifications for the transmission of DisplayPort video data over the PD communication protocol.
The application firmware is based on the X-CUBE-USB-PD certified software with Structured VDM messages to
negotiate Alternate Mode protocol requirements.
The firmware runs on the STM32F072 high performance ARM® 32-bit Cortex®-M0 MCU embedded in the
STEVAL-USBC2DP. It supports Billboard Device Class as per the USB Power Delivery standard and can be
updated through the device firmware upgrade functionality of the STM32 microcontroller.
UM2355
Reset button, connectors and jumper settings
UM2355 - Rev 2 page 8/20

2System setup
The STEVAL-USBC2DP dongle is a compact turn-key solution that demonstrates the versatility and convenience
of the USB Type-C port for DisplayPort Alternate Mode.
The plug and play feature of the USB Type-C and Power Delivery specifications allows the adapter to operate
immediately.
2.1 STEVAL-USBC2DP operation
To test the full functionality of the STEVAL-USBC2DP Type-C to DisplayPort adapter, your computer must support
DisplayPort Alternate Mode on the USB Type-C port where the dongle is connected.
Connect the STEVAL-USBC2DP USB Type-C plug directly to your computer USB Type-C port.
Connect the STEVAL-USBC2DP DisplayPort receptacle to the external monitor with a standard DisplayPort-to-
DisplayPort cable.
Once attached, the dongle resolves the explicit negotiation with the computer port and immediately extends the
computer screen to the secondary monitor.
Figure 11. STEVAL-USBC2DP connected to type-C port and to DP2DP cable
UM2355
System setup
UM2355 - Rev 2 page 9/20

Specific blinking sequences on the blue LED D13 indicate the different stages in the DisplayPort Alternate Mode
procedure:
1. If the dongle is attached to a USB Type-C ONLY port (without Power Delivery negotiation capability), the
LED remains OFF.
2. When the dongle is connected to a USB Type-C port that does not support Alternate Mode, the LED slowly
blinks after explicit PD negotiation is achieved.
3. When the dongle is connected to a port that supports DP Alternate Mode, but the DP cable is not attached to
connector CN2, the LED blinks quickly blinks after explicit PD negotiation is achieved and DP Alternate
Mode is confirmed with Discover Mode ACK.
4. When the dongle is connected to a port supporting DP Alternate Mode and the DP cable is attached
between connector CN2 and the display, the LED turns ON after DP Alternate Mode is achieved and the
computer screen is extended to the secondary display.
2.2 Analysis of DisplayPort Alternate Mode operation flows
The trace view below shows the sequence of the message exchange between the computer and the STEVAL-
USBC2DP dongle when it is first attached by DP-to-DP cable to the display, and then attached to the USB Type-C
port on the computer.
Note: See technical article TA0356 at STEVAL-USBC2DP for details regarding operation flows.
UM2355
Analysis of DisplayPort Alternate Mode operation flows
UM2355 - Rev 2 page 10/20