WLAN BLE Power Save#

1. Purpose / Scope#

The example demonstrates how to configure the device in WiSeConnect coex mode with WLAN standby mode and BLE-connected power save running in the RS9116W EVK module. In this coex application, a Silicon Labs BLE device connects with a remote BLE device (for example, a smartphone with an spp pro application) and issues a connected power save command to module.

The application uses both BLE and WLAN tasks to enable communication between a smartphone and a remote PC. Messages from the smartphone are received via BLE and forwarded through WLAN to the PC via an Access Point. Similarly, messages from the PC are sent via WLAN to BLE, enabling seamless bidirectional data transfer.

1.1 WLAN Task#

This application explains how to:

  • Create a Silicon Labs device as a station.

  • Connect a Silicon Labs station to remote access point and get an IP.

  • Enable the appropriate power save mode and then wait in a scheduler for some time.

  • Receive TCP data sent by the connected station and forward it to the BLE task.

  • Send data received by the BLE task to the connected station using TCP over SSL client protocol.

1.2 BLE Task#

This application explains how to:

  • Configure the device in advertise mode.

  • Connect from a smartphone/dongle.

  • Configure a device in power save profile mode 2.

  • Receive data from the WLAN task and send it to the connected remote BLE device via GATT.

  • Send data received from the remote BLE device via GATT to the WLAN task.

2. Prerequisites / Setup Requirements#

The WiSeConnect parts require that the host processor is connected to the WiSeConnect using an SPI, UART, or USB host interface. The host processor firmware needs to properly initialize the selected host interface. The Silicon Labs Wireless SAPI framework provides necessary HAL APIs to enable a variety of host processors.

Before running the application, the user will need the following things to setup.

2.1 Hardware Requirements#

  • Windows / Linux PC with Host interface (UART/ USB-CDC/ SPI/ USB) in case of WiSeConnect.

  • Silicon Labs RS9116 Wi-Fi Evaluation Kit

  • Host MCU Eval Kit. This example has been tested with:

  • Wireless Access point.

  • Windows PC2 with SSL server application (openssl).

  • BLE supported smart phone with GATT client application.

Setup diagram for WLAN BLE Power saveSetup diagram for WLAN BLE Power save

2.2 Software Requirements#

  • RS9116 SDK

  • Embedded Development Environment

  • Download and install OpenSSL from this link OpenSSL to download openssl in remote PC.

  • Download and install the Silicon Labs Simplicity Connect Mobile App in the Android smart phones for testing BLE applications. Users can also use their choice of BLE apps available in Android/iOS smart phones.

3. Application Build Environment#

3.1 Platform#

The Application can be built and executed on below Host platforms

3.2 Host Interface#

  • By default, the application is configured to use the SPI bus for interfacing between Host platforms and the RS9116W EVK.

  • The SAPI driver provides APIs to enable other host interfaces if SPI is not suitable for your needs.

3.3 Project Configuration#

The Application is provided with the project folder containing Keil and Simplicity Studio project files.

  • Keil Project

    • The Keil project is used to evaluate the application on STM32.

    • Project path: <SDK>/examples/snippets/wlan_ble/wlan_ble_power_save/projects/wlan_ble_power_save-nucleo-f411re.uvprojx

  • Simplicity Studio

    • The Simplicity Studio project is used to evaluate the application on EFR32MG21.

    • Project path:

      • If the Radio Board is BRD4180A or BRD4181A, then access the path <SDK>/examples/snippets/wlan_ble/wlan_ble_power_save/projects/wlan_ble_power_save-brd4180a-mg21.slsproj

      • If the Radio Board is BRD4180B or BRD4181B, then access the path <SDK>/examples/snippets/wlan_ble/wlan_ble_power_save/projects/wlan_ble_power_save-brd4180b-mg21.slsproj

      • User can find the Radio Board version as given below

EFR Radio BoardsEFR Radio Boards

Bare Metal Support#

This application supports only bare metal environment. By default, the application project files (Keil and Simplicity Studio) are provided with bare metal configuration.

4. Application Configuration Parameters#

The application can be configured to suit your requirements and development environment. Read through the following sections and make any changes needed.

4.1 Configuring the WLAN task#

4.1.1 Open the rsi_wlan_app.c file and modify the following macros:

SSID refers to the name of the Access point.

#define SSID                                          "REDPINE_AP"

CHANNEL_NO refers to the channel in which device should scan. If it is 0, device will scan all channels.

#define CHANNEL_NO                                     0

SECURITY_TYPE refers to the type of security. In this application STA supports Open, WPA-PSK, and WPA2-PSK securities.

Valid configuration is:

  • RSI_OPEN - For OPEN security mode

  • RSI_WPA - For WPA security mode

  • RSI_WPA2 - For WPA2 security mode

#define SECURITY_TYPE                                 RSI_OPEN

PSK refers to the secret key if the access point is configured in WPA-PSK/WPA2-PSK security modes.

#define PSK                                           "<psk>"

To Load certificate:

#define LOAD_CERTIFICATE                              1

If LOAD_CERTIFICATE is set to 1, application will load certificate which is included using rsi_wlan_set_certificate API.

By default, the application loads "cacert.pem" certificate if LOAD_CERTIFICATE is enable. In order to load different certificate, user has to follow the following steps:

rsi_wlan_set_certificate API expects the certificate in the form of linear array. So, convert the pem certificate into linear array form using python script provided in the release package "certificate_script.py".

Example: If the certificate is wifi-user.pem, give the command in the following way:

python certificate_to_array.py <input_file> <output_file>
Example: python certificate_to_array.py wifi-user.pem wifiuser.pem

The script will generate wifiuser.pem in which one linear array named wifiuser[] contains the certificate.

After converting the certificate, update the rsi_wlan_app.c source file by including the certificate file and by providing the required parameters to the rsi_wlan_set_certificate API.

Note: Once the certificate loads into the device, it will write into the device flash. So, the user does not need the load certificate for every boot up unless the certificate changes.

Define LOAD_CERTIFICATE as 0 if the certificate is already present in the Device.

Note: All the certificates are given in the release package <SDK>/resources/certificates

DEVICE_PORT port refers to SSL client port number.

#define DEVICE_PORT                                  5001

SERVER_PORT port refers to remote the SSL server port number.

#define SERVER_PORT                                  5001

SERVER_IP_ADDRESS refers to the remote peer IP address to connect with SSL server socket.

#define SERVER_IP_ADDRESS                           "192.168.10.100"

To configure IP address

Enable / Disable: DHCP mode 1-Enables DHCP mode (gets the IP from DHCP server), 0-Disables DHCP mode

#define DHCP_MODE                             1

If user wants to configure module IP address through STATIC IP, then configure the DEVICE_IP, GATEWAY and NETMASK macros as below.

#define   DEVICE_IP                           "192.168.10.101"
#define   GATEWAY                             "192.168.10.1"
#define   NETMASK                             "255.255.255.0"

4.1.2 In the rsi_ble_app.c file, default power save mode configuration is set to low power mode 2 (RSI_SLEEP_MODE_2) with maximum power save (RSI_MAX_PSP) with a message-based hand shake.

#define PSP_MODE  RSI_SLEEP_MODE_2
#define PSP_TYPE  RSI_MAX_PSP

4.1.3 Open the rsi_wlan_config.h file and modify following macros:

#define CONCURRENT_MODE                              RSI_DISABLE
#define RSI_FEATURE_BIT_MAP                          (FEAT_SECURITY_OPEN | FEAT_AGGREGATION | FEAT_ULP_GPIO_BASED_HANDSHAKE | FEAT_DEV_TO_HOST_ULP_GPIO_1)
#define RSI_TCP_IP_BYPASS                            RSI_DISABLE
#define RSI_TCP_IP_FEATURE_BIT_MAP                   (TCP_IP_FEAT_DHCPV4_CLIENT | TCP_IP_FEAT_SSL | TCP_IP_FEAT_EXTENSION_VALID)
#define RSI_CUSTOM_FEATURE_BIT_MAP                   (FEAT_CUSTOM_FEAT_EXTENTION_VALID | CUSTOM_FEAT_SOC_CLK_CONFIG_120MHZ)
#define RSI_EXT_CUSTOM_FEATURE_BIT_MAP               (EXT_FEAT_LOW_POWER_MODE | EXT_FEAT_XTAL_CLK_ENABLE | EXT_FEAT_384K_MODE)
#define RSI_EXT_TCPIP_FEATURE_BITMAP                 EXT_TCP_IP_WINDOW_DIV
#define RSI_BAND                                     RSI_BAND_2P4GHZ

Default configuration of low power save mode 2:

#define RSI_HAND_SHAKE_TYPE GPIO_BASED
#define RSI_SELECT_LP_OR_ULP_MODE RSI_ULP_WITH_RAM_RET
#define RSI_DTIM_ALIGNED_TYPE 0
#define RSI_MONITOR_INTERVAL 50
#define RSI_WMM_PS_ENABLE RSI_DISABLE
#define RSI_WMM_PS_TYPE 0 
#define RSI_WMM_PS_WAKE_INTERVAL 20
#define RSI_WMM_PS_UAPSD_BITMAP 15

4.2 Configuring the BLE task#

4.2.1 Open the rsi_ble_app.c file and modify following macros:

RSI_BLE_NEW_SERVICE_UUID refers to the newly created custom service.

#define RSI_BLE_NEW_SERVICE_UUID                     0xAABB

RSI_BLE_ATTRIBUTE_1_UUID refers to the first characteristic under this custom service (RSI_BLE_NEW_SERVICE_UUID).

#define RSI_BLE_ATTRIBUTE_1_UUID                      0x1AA1

RSI_BLE_ATTRIBUTE_2_UUID refers to the second characteristic under this custom service (RSI_BLE_NEW_SERVICE_UUID).

#define RSI_BLE_ATTRIBUTE_2_UUID                      0x1BB1

RSI_BLE_MAX_DATA_LEN refers to the maximum length of the attribute data.

#define RSI_BLE_MAX_DATA_LEN                         20

RSI_BLE_APP_DEVICE_NAME refers to the name of the Silicon Labs device to appear during scanning by remote devices.

#define RSI_BLE_APP_DEVICE_NAME                       "WLAN_BLE_SIMPLE_CHAT"

Following are the non-configurable macros in the application:

RSI_BLE_CHAR_SERV_UUID refers to the client characteristic declaration.

#define RSI_BLE_CHAR_SERV_UUID                         0x2803

RSI_BLE_CLIENT_CHAR_UUID refers to the client characteristic configuration descriptor.

#define RSI_BLE_CLIENT_CHAR_UUID                       0x2902

RSI_BLE_ATT_PROPERTY_READ is used to set the READ property to an attribute value.

#define RSI_BLE_ATT_PROPERTY_READ                       0x02

RSI_BLE_ATT_PROPERTY_WRITE is used to set the WRITE property to an attribute value.

#define RSI_BLE_ATT_PROPERTY_WRITE                    0x08

RSI_BLE_ATT_PROPERTY_NOTIFY is used to set the NOTIFY property to an attribute value.

#define RSI_BLE_ATT_PROPERTY_NOTIFY                   0x10

4.2.2 Open rsi_ble_config.h file. User can also modify the below parameters as per their needs and requirements.

#define RSI_BLE_PWR_INX                               30
#define RSI_BLE_PWR_SAVE_OPTIONS                      0

5. Testing the Application#

Follow the below steps for the successful execution of the application.

5.1 Loading the RS9116W Firmware#

Refer Getting started with PC to load the firmware into RS9116W EVK. The firmware binary is located in <SDK>/firmware/

5.2 Building the Application on the Host Platform#

5.2.1 Using STM32#

Refer STM32 Getting Started

  • Open the project <SDK>/examples/snippets/wlan_ble/wlan_ble_power_save/projects/wlan_ble_power_save-f411re.uvprojx in Keil IDE.

  • Build and Debug the project

  • Check for the RESET pin:

    • If RESET pin is connected from STM32 to RS9116W EVK, then user need not press the RESET button on RS9116W EVK before free run.

    • If RESET pin is not connected from STM32 to RS9116W EVK, then user need to press the RESET button on RS9116W EVK before free run.

  • Free run the project

  • Then continue the common steps from Section 5.3

5.2.2 Using EFX32#

Refer EFx32 Getting Started

  • Import the project from <SDK>/examples/snippets/wlan_ble/wlan_ble_power_save/projects

  • Select the appropriate .slsproj as per Radio Board type mentioned in Section 3.3

  • Compile and flash the project in to Host MCU

  • Debug the project

  • Check for the RESET pin:

    • If RESET pin is connected from EFX32 to RS9116W EVK, then user need not press the RESET button on RS9116W EVK before free run

    • If RESET pin is not connected from EFX32 to RS9116W EVK, then user need to press the RESET button on RS9116W EVK before free run

  • Free run the project

  • Then continue the common steps from Section 5.3

5.3 Common Steps#

  1. Configure the access point in OPEN/WPA-PSK/WPA2-PSK mode to connect Silicon Labs device in STA mode.

  2. On Windows PC2, which is connected to the AP through LAN. Download the Openssl package from above mentioned link and run SSL server by giving following command:

Openssl.exe s_server -accept <SERVER_PORT> –cert <server_certificate_file_path> -key <server_key_file_path> -tls<tls_version>
Example: openssl.exe s_server –accept 5001 –cert server-cert.pem -key server-key.pem –tls1

OpenSSL server WindowOpenSSL server Window

  1. After the program gets executed, Silicon Labs BLE is in Advertising state and WLAN connects to the Access Point and establishes SSL connectivity with SSL server opened on Windows PC2. The following image illustrates the connection establishment at Windows PC2.

OpenSSL server log WindowOpenSSL server log Window

  1. Open Simplicity Connect app in the smartphone and perform the Scan.

  2. In the App, the Silicon Labs module device will appear with the name configured in the macro RSI_BLE_APP_DEVICE_NAME (Ex: "WLAN_BLE_APP") or sometimes observed as a RS9116W EVK as internal name "SimpleBLEPeripheral".

WLAN_BLE_APP Mobile screenshotWLAN_BLE_APP Mobile screenshot

  1. Initiate the BLE connection from the app.

BLE connection Mobile screenshotBLE connection Mobile screenshot

  1. Once the connection is established, the SiConnect app displays all services supported by the Silicon Labs module.

  2. After the BLE connection is set up, the device enters the configured coex power-save mode.

  3. Select the custom service which is added RSI_BLE_NEW_SERVICE_UUID (for example, 0xAABB) and enable Notification for attribute UUID RSI_BLE_ATTRIBUTE_2_UUID (for example, 0x1BB1) to receive data sent by Wi-Fi STA.

Enable Read Notification Mobile screenshotEnable Read Notification Mobile screenshot

  1. From SSL server (Windows PC2), send a message (for example, Hello from WiFi STA) to the Silicon Labs device. The Silicon Labs device forwards the received message from SSL server to remote BLE device which is connected to Silicon Labs BLE device over BLE protocol. User can observe the message notification on attribute UUID RSI_BLE_ATTRIBUTE_2_UUID (for example, 0x1BB1) in the SiConnect app.

Message Notification WindowMessage Notification Window

Attribute UUID Mobile screenshotAttribute UUID Mobile screenshot

Note: The rsi_wlan_app_send_to_ble() function defined in rsi_ble_app.c sends a message from the WLAN task to BLE task.

  1. Now send a message (for example, Hello from BLE) from GATT client (from the smartphone SiConnect app) using attribute RSI_BLE_ATTRIBUTE_1_UUID (for example, 0x1AA1) to Silicon Labs device. Silicon Labs device forwards the received message from BLE remote device to SSL server over Wi-Fi protocol. The user can observe the message on SSL socket application.

Enable Write Notification Mobile screenshotEnable Write Notification Mobile screenshot

Send Message Mobile screenshotSend Message Mobile screenshot

Message on SSL socket WindowMessage on SSL socket Window

Note: rsi_bt_app_send_to_wlan() function is defined in rsi_wlan_app.c to send message from BLE task to WLAN task.

  1. Note down the power measurement by connecting Module to Agilent Power meter setup.

Compressed Debug Logging#

To enable the compressed debug logging feature please refer to Logging User Guide