Silicon Laboratories WFM200S User manual

UG407: WFM200S Wi-Fi® Expansion Kit
User's Guide
The WFM200S Wi-Fi Expansion Kit is an excellent way to ex-
plore and evaluate the WFM200S Wi-Fi Transceiver Module with
a Raspberry Pi or an EFM32 MCU for your embedded applica-
tion.
The WFM200S Wi-Fi Transceiver Module is an easy to use and easy to interface Wi-Fi
Network Co-Processor (NCP). Most of the associated complexity of Wi-Fi and the pro-
tocol stack is offloaded to the NCP and allows for easy Wi-Fi integration into any em-
bedded system.
The kit easily integrates and brings Wi-Fi connectivity to a compatible Silicon Labs
MCU Starter Kit through the EXP header. The WFM200S Wi-Fi Expansion Kit has also
been designed after the Raspberry Pi Hardware Attached on Top (HAT) board specifi-
cation, allowing the WFM200S Wi-Fi Expansion Kit to connect to a Raspberry Pi.
WFM200S EXPANSION BOARD FEATURES
• Selectable SPI or SDIO host interface
• EXP connector for interfacing Silicon
Labs Starter Kits
• Allows board detection and
identification
• Raspberry Pi compatible HAT
• 40-pin header
• HAT EEPROM for identification
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Table of Contents
1. Introduction ................................3
1.1 Kit Contents ...............................4
2. Hardware Overview .............................5
2.1 Hardware Layout .............................5
3. WFM200S Wi-Fi NCP Expansion Kit .......................6
3.1 Host Interfaces ..............................6
3.2 Power-on and Manual Reset Circuit .......................7
4. Connectors ................................8
4.1 EXP Header ...............................9
4.1.1 Pass-through EXP Header ........................9
4.1.2 EXP Header Pinout ...........................10
4.2 Raspberry Pi Connector ...........................11
4.2.1 Raspberry Pi Connector Pinout .......................12
4.3 External FEM Connector ..........................13
4.3.1 External FEM Connector Pinout .......................13
4.4 PTA Connector ..............................14
4.4.1 PTA Connector Pinout ..........................14
4.5 Secondary RF Connector ..........................14
4.6 Power Supply ..............................15
5. Schematics, Assembly Drawings, and BOM ...................16
6. Kit Revision History ............................17
6.1 SLEXP8023A Revision History ........................17
6.2 SLEXP8023C Revision History ........................17
7. Document Revision History .........................18
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1. Introduction
This user guide describes the WFM200S Wi-Fi Expansion Kit. The kit connects to either a Silicon Labs EFM32 MCU starter kit (STK), a
Silicon Labs EFR32 wireless starter kit (WSTK) or a Raspberry Pi equipped with the 40-pin Raspberry Pi hardware-attached-on-top
(HAT) connector. SDIO support is available only with selected hosts.
Figures 1.1 and 1.2 shows the kit connected to a Silicon Labs MCU STK through the Expansion Header and a Raspberry Pi, respec-
tively.
Figure 1.1. WFM200S Wi-Fi Expansion Kit Connected to a Silicon Labs EFM32GG11 MCU STK
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Introduction
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Figure 1.2. WFM200S Wi-Fi Expansion Kit Connected to a Raspberry Pi
Note: Do not connect the kit to both a Silicon Labs MCU STK and a Raspberry Pi at the same time.
1.1 Kit Contents
The WFM200S Wi-Fi Expansion Kit comes in two versions, which differs in what's included in the box:
• SLEXP8023A:
• BRD8023A WFM200S Wi-Fi EXP Board
• 8 GB Micro-SD card with software image for Raspberry Pi 2
• SLEXP8023C:
• BRD8023A WFM200S Wi-Fi EXP Board
• 8 GB Micro-SD card with software image for Raspberry Pi 2
• Raspberry Pi 2 Model B Single-Board Computer
• Raspberry Pi Power Supply 5.1 V, 2.5 A
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Introduction
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2. Hardware Overview
2.1 Hardware Layout
The layout of the WFM200S Wi-Fi Expansion Kit is shown in the figure below.
EXP-header for
Starter Kits
Power source
select switch
Pass-through EXP-header
Not mounted
WFM200S Wi-Fi Transceiver
Raspberry Pi connector
On bottom side
Current consumption
measurement header
Not mounted
WFM200S Wi-Fi
Expansion Board
Host interface
select switch
Secondary RF output
coaxial connector
TX/RX Activity LED
External FEM header
Not mounted
PTA header
Not mounted
Reset button
Figure 2.1. WFM200S Wi-Fi Expansion Kit Hardware Layout
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Hardware Overview
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3. WFM200S Wi-Fi NCP Expansion Kit
The WFM200S Wi-Fi Transceiver Module is a Wi-Fi Network Co-Processor (NCP) transceiver from Silicon Labs.
3.1 Host Interfaces
SPI and SDIO are the two available host interfaces (HIF) on the WFM200S Wi-Fi Expansion Kit. A slide switch, whose state is sampled
during power-on reset or manually issued reset is used to select the interface. The slide switch must remain in the same position
throughout the duration of the session since it also controls HIF selection multiplexer circuits.
When the WFM200S Wi-Fi Expansion Kit is connected to an EFM32/EFR32 starter kit through the EXP header, the state of the HIF
selection switch can be read (but not controlled) by the kit mcu through a GPIO pin.
The WFM200S Wi-Fi Expansion Kit incorporates a set of multiplexer circuits which allows the user to use the same kit for evaluating the
WFM200S in both applications requiring SPI or SDIO connectivity to the host. These circuits will normally not be needed in an end-user
application since in most cases the interface to use will be fixed.
A simplified circuit diagram showing the host interface multiplexer circuits is shown below. The EXP_HEADER9 signal is connected to
pin 9 on the EXP header, while the HIF_OEn output enable signal is controlled by the power-on reset circuit (explained later).
Figure 3.1. Host Interface Multiplexer Circuit
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
WFM200S Wi-Fi NCP Expansion Kit
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3.2 Power-on and Manual Reset Circuit
To ensure that the state of the host interface selection signal is sampled correctly at the rising edge of the WFM200S RESETn signal, a
power-on reset circuit has been added to the WFM200S Wi-Fi Expansion Kit. This circuit achieves this by
• Adding a delay of 1ms to the rising edge of the RESETn signal with respect to the rising edge of the power supply
• Isolating the host from the WFM200S DAT2/HIF_SEL pin during the rising edge of the RESETn signal
The figure below shows the circuit diagram for the power-on and manual reset circuit. Its functionality is as follows:
• NCP_RESETn is the active-low reset signal of the WFM200S. The WFM200S RESETn pin has an internal pull-up of approximately
43 kOhms. The on-board reset button is connected to this signal.
• HIF_SEL_CTRL is the signal from the HIF selection switch
• HIF_OEn is the active-low output enable signal of the HIF multiplexer circuits
• WF_DAT2_HIF_SEL is the combined SDIO DAT2 signal and HIF selection signal of the WFM200S
• U114 is an open-drain active low output reset monitor which with the installed capacitor connected to the CD pin keeps NCP_RE-
SETn tied to ground for about 1 ms after VMCU_NCP has exceeded the threshold voltage of 0.9 V
• U115 is a tri-state output buffer with an active low output enable signal connected to NCP_RESETn which pulls the CD pin of U116
low while NCP_RESETn is low
• U116 is a push-pull active high output reset monitor which drives HIF_OEn high for 1 ms after the output of U115 is disabled
• U109 is a tri-state output buffer with an active high output enable signal which connects the HIF_SEL_CTRL signal to the
WF_DAT2_HIF_SEL signal as long as HIF_OEn is high
The NCP_RESETn signal is available on both the EXP header and the Raspberry Pi connector and can be used for issuing a manual
reset sequence by pulling it low for at least 1 ms.
Note: Reset button is effective when board is not connected to MCU or Raspberry Pi boards. When connected, change of host inter-
face is effective after reboot.
Figure 3.2. Power-on and Manual Reset Circuit Diagram
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
WFM200S Wi-Fi NCP Expansion Kit
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4. Connectors
This chapter gives an overview of the WFM200S Wi-Fi Expansion Kit connectivity and power connections.
Pass-through
EXP Header
(Not Mounted)
EXP Header
Raspberry Pi
Connector
(Bottom side)
External FEM
connector
(Not Mounted)
PTA connector
(Not Mounted)
Secondary RF
output connector
Current consumption header
(Not Mounted)
Figure 4.1. WFM200S Wi-Fi Expansion Kit Connector Layout
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Connectors
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4.1 EXP Header
On the left-hand side of the WFM200S Wi-Fi Expansion Kit, a right-angle female 20-pin EXP header is provided to connect to one of
Silicon Labs’ supported Starter Kits. The EXP header on the Starter Kits follows a standard which ensures that commonly used periph-
erals such as an SPI, a UART, and an I2C bus, are available on fixed locations on the connector. Additionally, the VMCU, 3V3 and 5 V
power rails are also available on the expansion header. For detailed information regarding the pinout to the expansion header on a
specific Starter Kit, consult the accompanying user’s guide.
The figure below shows how the WFM200S Wi-Fi Transceiver Module is connected to the connector and the peripheral functions that
are available.
12
4
8
6
10
3
5
9
7
12
13
14
11
1516
17
18
20 19
VMCU
SPI_MOSI / SDIO_DAT1
SPI_MISO / SDIO_DAT0
SPI_SCLK / SDIO_CMD
SPI_CS / SDIO_CLK
SPI_WIRQ / SDIO_DAT3
SDIO_DAT2
Not Connected (NC)
5V
3V3
GND
GPIO_WUP
Not Connected (NC)
RESETn
HIF_SEL_CTRL
Not Connected (NC)
Not Connected (NC)
Not Connected (NC)
BOARD_ID_SDA
BOARD_ID_SCL
Reserved (Board Identification)
WFM200S I/O Pin
Figure 4.2. Expansion Header
4.1.1 Pass-through EXP Header
The WFM200S Wi-Fi Expansion Kit features a footprint for a secondary EXP header. All signals from the EXP header, including those
that are not connected to any features on the WFM200S Wi-Fi Expansion Kit, are directly tied to the corresponding pins in the footprint,
allowing daisy-chaining of additional expansion boards if a connector is soldered in.
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Connectors
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4.1.2 EXP Header Pinout
The table below shows the pin assignments of the EXP header.
Table 4.1. EXP Header Pinout
EXP Header
Pin Function
2 WFM200S voltage domain (power switch set to EXP VMCU)
4 SPI_MOSI / SDIO_DAT1
6 SPI_MISO / SDIO_DAT0
8 SPI_SCLK / SDIO_CMD
10 SPI_CS / SDIO_CLK
12 SPI_WIRQ / SDIO_DAT3
14 SDIO_DAT2
16 Not Connected
18 Board 5 V supply. Used to supply LDO regulator.
20 Board 3V3 supply. Only used for board identification.
1 Ground
3 GPIO (WFM200S WUP)
5 Not Connected
7 GPIO (WFM200S RESETn)
9 GPIO (HIF_SEL_CTRL read access)
11 Not Connected
13 Not Connected
15 Not Connected
17 Identification of expansion boards.
19 Identification of expansion boards.
UG407: WFM200S Wi-Fi® Expansion Kit User's Guide
Connectors
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