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10 January 2020

STMicro makes LoRa waves with Tencent and Semtech, new SoC

STMicroelectronics, a Swiss silicon specialist, has announced a new partnership with Semtech, to create a System-on-Chip (SoC) that combines one of STMicro’s STM32 microcontrollers (MCU) with a LoRa radio. The single-chip LoRa offering should catch developer attention, and a cooperation partnership with Tencent Cloud won’t hurt its Chinese ambitions either.

Semtech, the owner of the IP behind the LoRa physical layer, was initially the only supplier of LoRa radio silicon. Licensing partnerships with Microchip and STMicro came later, expanding the choice of silicon providers for LoRa adopters – but always ensuring that Semtech got a royalty. Now, STMicro seems to have taken things a step further, in building the STM32WLE5 SoC – combining the application processor (the MCU) with the radio.

STMicro made a big deal out of its 10-year support commitment, which should tick a few boxes for those wanting to use the new SoC. The 5mm x 5mm package has the full integration with the rest of STMicro’s STM32 ecosystem, which is much used in the IoT, as well as the certified LoRaWAN stack – which is powering the radio component that is based on the Semtech SX126x.

The STM32 here is based on Arm’s Cortex-M4 MCU, clocked at 48 MHz, and the SoC can be equipped with 64 KB, 128 KB, or 256 KB of flash memory. STMicro’s STM32LA security features are also provided, including a true random number generator (TRNG) and a public key accelerator (PKA). This should equate to a pretty secure end-device, with enough memory for most standard applications.

The pair say that the radio has both a high-power and low-power transmitter mode, which supports whole of the sub-GHz unlicensed frequency bands from 150 MHz to 960 MHz. To this end, STMicro is billing this as a global proposition, with sensitivity down to -148 dBm, and two sets of power amplifiers (15 dBm and 22 dBm), to maximize range.

“Our new wireless STM32 SoC extends the existing STM32W Wireless and simplifies new-product development while saving bill-of-materials costs and maximizing system reliability and energy efficiency,” said Ricardo De Sa Earp, Microcontroller Division General Manager, STMicroelectronics. “In addition, by leveraging the STM32 MCU architecture, we let developers easily introduce wireless connectivity in existing embedded designs by porting to the STM32WLE5.”

The SoC supports the LoRa ‘chirp’ modulation, as well as GFSK, GMSK, and BPSK modulation, meaning you could run other protocols on it, should you wish. As Haystack Technologies founder JP Norair put it, “you can remove the broken LoRa FEC (forward error correction) entirely, and replace with your own.”

Haystack is somewhat in the business of taking jabs at LoRa. It markets its DASH7-based XR stack as a way to unlock the actual potential of the silicon, and in that barb, Norair said that being able to remove the FEC would provide an additional 20% to the performance of XR2. Haystack says it will be adopting the new STM32WLE5 in its products in 2020.

In its announcement, Haystack digs through the technical details about the new SoC, noting that while it is essentially ‘just a SX1262 and STM32L4 bolted onto the same die, a careful reading of the product manual reveals a few novel features.’

New power routing features in firmware mean that Haystack no longer plans to add silicon to solve LoRa power consumption quirks, and the company says that the design also supports Sigfox and Sony’s mysterious Eltres protocol (currently only promoted in Japan. The third notable feature is the aforementioned ability to ditch the FEC, because users can now disable the Hamming coding, and hardware semaphores and the PKA will allow the likes of Haystack to run a guest RTOS on the SoC – thanks to the availability of extra memory.

Haystack also says that it found that STMicro lists different spreading factor sensitivities to those that Semtech, which are particularly notable at higher sensitivities. As Haystack notes, “it’s uncertain if these figures are due to application of better testing than Semtech had done previously (their lab benchmarks are suspicious and much more optimistic than our own testing), or simply higher noise levels in the integrated package.”

STMicro’s other recent announcement, the Tencent Cloud partnership, is perhaps less exciting, but it could open serious doors in China. Tencent will be integrating its TencentOS Tiny LoRaWAN operating system on STM32 chips, which is tightly integrated with Tencent’s cloud computing platform. The goal is quicker time-to-market for customers, and given Tencent’s position in China, this could spark a nice uptick in sales for STMicro.

“As a market leader in 32-bit MCUs with a powerful ecosystem and IoT-related infrastructure, the STM32 is a natural first choice for the anchor platform for Tencent’s IoT OS,” said Arnaud Julienne, a VP in STMicro’s APAC division. “Combining Tencent’s leading IoT platform with ST’s strong LoRaWAN solutions and support of robust STM32 ecosystem assures best-in-class experience to Chinese IoT developers and customers.”

“ST is the most influential MCU product partner in Tencent Cloud IoT solutions. We will work closely to serve the IoT industry, jointly expand the business ecosystem, and build the industrial IoT New situation,” said Yachen Wang, General Manager of Tencent Cloud Network.