 Hello, and welcome to this presentation of the SIGFOX protocol. SIGFOX is using the free, unlicensed spectrum below 1 GHz. It uses an ultra-narrow band. The signal transmitted by a SIGFOX object requires only 100 Hz of band, 600 Hz for FCC regions. Its main characteristics are bi-directional, half-duplex, TX, then RX. It can deliver small messages up to 12 bytes with a maximum of 144 messages per day. With a large link budget of 140 dB, the achievable range is over 10 kmS. The network architecture is shown in this picture. SIGFOX IoT objects, which may run on battery, are wirelessly connected to the SIGFOX network. The SIGFOX network is composed of SIGFOX base station, relaying messages to the SIGFOX back-end server. Messages are forwarded to third-party application servers that may be used to manage a fleet of devices. The European, North American, and Asian markets have different spectrum allocations and regulatory requirements. SIGFOX has split requirements in various region configurations called RC. Seven region configurations are available and are depicted in this picture. SIGFOX uses ultra-narrowband modulated signals to send information to the SIGFOX network, enabling many devices to send data concurrently to the SIGFOX network. SIGFOX is using 192 kHz of the publicly available band to exchange messages over the air. Each message is 100 Hz wide and transferred with a data rate of 100 bits per second, or 600 Hz wide with a data rate of 600 Hz depending on the region. SIGFOX RF specifications for medium access are depicted in this table. Frequencies, data rates, output power, and medium access depend on the region where the device is operating. Three main groups of RF specifications can be highlighted which feature same data rates. For example, duty cycle, regions RC1, RC6, and RC7, frequency hopping, regions RC2 and RC4, and LBT, regions RC3 and RC5. Duty cycle is 1% of the time per hour. For 8-12 bytes payload, this means 6 messages per hour leading to 140 messages per day. Regarding frequency hopping, the device broadcasts each message three times on three different frequencies, maximum on time 400 milliseconds per channel, no new emission before 20 seconds, listen before talk or LBT. Devices must verify that the SIGFOX operated 200 kHz channel is free of any single stronger than minus 80 dBm during 5 milliseconds before transmitting. When the channel is free, the device starts a transmission. The transmission is not started otherwise. The end device transmits data to the network in an asynchronous manner, as transmission data is only sent per device report event. The figures below depict the timing sequences with and without a downlink. The three transmissions, TX1, TX2, and TX3 contain the same payload information. These consecutive transmissions only maximize the probability of a correct reception by the network. When the device observes a good link quality to the network, it may decide to send only TX1 to save power consumption, only if downlink frame is requested. Note that TX periods depend on the number of bytes sent and on the RC zone. It takes 10 milliseconds to send a bit in RC1 and RC3C. It takes 1.66 milliseconds to send a bit in RC2 and RC4. A message can be 26 bytes long at the most, including sync word, header and payload data. Therefore, for RC1, a TX period can be maximum 26 by 8 by 10 milliseconds, equals 2.08 seconds. The device transmits a message on a random frequency and then sends two replicas on different frequencies and time slots. The SIGFOX base stations monitor the full 192 kHz spectrum and look for any ultra-narrow band or UNB signals to demodulate at any time and any frequency. Monarch is a SIGFOX beacon emitted from a point of interest or POI. The Monarch beacon is emitted at a frequency allowed by the region the POI belongs to. The beacon contains region configuration or RC information that a Monarch capable device can demodulate. Upon reception of this information, the Monarch capable device is able to switch automatically to the right region configuration and can send information to the network. The Monarch feature allows a SIGFOX IoT device to roam seamlessly around the world. The Monarch signal is sent at POI every 5 minutes plus a random back-off period of 10 seconds. The frequency of the beacon is region-specific. The beacon lasts in total 400 milliseconds. If a device clock is set, it is hence possible to open a scan window only when the Monarch signal is present to reduce current consumption of the end device. The SIGFOX ecosystem integrates the security by default, authentication and integrity, anti-replay on messages propagated on the network, sequence number, cryptography based on advanced encryption standard or AES with no key over-the-air transmission, payload encryption as an option to ensure the confidentiality of the data. There are three different levels of security. Medium level. The security credentials are stored in the device. High level. The security credentials are stored in an SW-based protected area using the key management system or KMS. And very high level. The security credentials can be stored in a secure element. Two types of SIGFOX applications are provided in the STM32 Cube WL firmware package. Both applications are available for single-core devices and dual-core devices. Only single-core SIGFOX application architecture is depicted here. The HAL uses STM32 Cube APIs to drive the hardware required by the application. The RTC provides a centralized time unit that continues to run even in the low-power stop mode. The RTC alarm is used to wake up the system at specific times managed by the timer server. The SIGFOX core library embeds the medium access controller or MAC as well as some security functions. The application is built around an infinite loop including a scheduler. The scheduler processes tasks and events. When nothing remains to be done, the scheduler transitions to idle state and calls the low-power manager. Any SIGFOX device must pass the SIGFOX certification to communicate on the SIGFOX network. The SIGFOX delivers the SIGFOX verified certificate to acknowledge compliance to SIGFOX RF and protocol specifications of a modular design and development solution. SIGFOX Ready certification is mandatory for any device to be connected to the SIGFOX network. A device candidate for SIGFOX Ready certification must comply to all SIGFOX certification specifications. SIGFOX RF and protocol and SIGFOX radiated performance. More info can be found at build.sigfox.com slash certification. The system including the Nucleo WL55JC board and the STM32CUBWL Firmware Modem application has been verified by the SIGFOX test lab and passed the SIGFOX verified certification. All test modes are available via AT commands. The coming slides describe the successive steps to make a communication with the SIGFOX network. First, compile and load a SIGFOX AT Slave project from the STM32WL firmware package. Then, start the STM32CUBWL programmer and connect to the STM32WL. A button labeled SIGFOX Credentials is added on the main menu on the left-hand side. After opening the SIGFOX Credentials window, the chip certificate is extracted automatically with 136-byte size and displayed in the chip certificate area. This certificate can be saved in a binary file and copied to the clipboard. ST provides a web interface on my.st.com where the user can get the SIGFOX trial credentials. Go to my.st.com slash sfxp and register on my.st.com to create a specific user account, if not yet done. Then, paste the certificate extracted with STM32CUBWL programmer into the form. If the certificate is valid, click on the download button and the zip file is automatically downloaded on the user computer. Once unzipped, the credentials can be loaded in the STM32WL device using the SIGFOX Credential Provisioning Area in the STM32CUBWL programmer. Use the proper AT commands to get the SIGFOX ID and SIGFOX PAC. Log in on by.sigfox.com slash activate, paste the device ID and PAC into the activate and click Next, and the device will be activated. To see the message, log on back-end.sigfox.com and browse to the device list where the device should be visible. Data can be sent using the AT dollar sign SF command on the terminal. The device sends data to the SIGFOX network and messages are visible on the back-end. Click on the device ID and the Go on the messages tab. More information can be found in AN5480 regarding the way to build a SIGFOX application with STM32CUBWL.