EYE on NPI – STM32WLE5C8U6 32-Bit Wireless Long-Range MCU #EyeOnNPI #DigiKey @ST_World @DigiKey
56This week's EYE ON NPI is going looooooooong with new ST chips that have embedded long range radios inside. That's right, we're talking about the STM32WLE5x series of 32-bit Wireless Long Range MCUs (https://www.digikey.com/en/product-highlight/s/stmicroelectronics/stm32wlex-32-bit-wireless-long-range-mcus).
We like LoRa here at Adafruit - we have breakouts, Bonnets, even Feathers with microcontrollers + LoRa radio modules added on for easy radio projects. (https://www.adafruit.com/?q=lora&sort=BestMatch) Now seeing this all-in-one chip from ST is pretty exciting - it combines a powerful-but-low-power ST microcontroller and a sub-GHz radio chip all in one package, and at the same price we'd normally pay for just the radio module or chip. (https://www.digikey.com/en/products/detail/semtech-corporation/SX1276IMLTRT/4259565) What a good deal!
LoRa is one of our favorite wireless protocols, alongside cellular, Bluetooth LE and WiFi. All four are common for 'last-mile' connectivity. And of them, LoRa gives you the low power of BLE, with better range than WiFi and without the cost of cellular.
LoRa/SigFox and other 'sub-GHz protocols' are usually called LPWAN (low power wide area networks). LPWAN devices are not new technology, in fact, cellular is essentially a national-sized version of one. But for people who don’t want to tie into the cellular network, and don’t need the bandwidth, LPWANs can give you excellent range for very little power and not very much money!
These networks can reach for many miles outdoors, even in high-density cities. They’re perfect in country-sides, rural and semi-urban spots, especially if you have the ability to set up a directional antenna in a high spot. What’s great about all of them is there’s no complex pairing, connection or authentication overhead (unless you want it) so you can wake up your setup and start transmitting within milliseconds. (https://learn.adafruit.com/alltheiot-transports/lora-sigfox)
The only 'downside' to LoRa is that you do have to manage the network and create a gateway to the greater internet if you want to send/receive data from servers, say for data logging or alerts.
Compare this to WiFi and cellular which have internet capability baked in.
That said, there's a grass-roots effort by The Things Network to create a free/open gateway network for LoRaWAN with low cost gateways for both indoor and outdoor use. And there are literally hundreds of development kits, boards and modules you can use to add LoRaWAN support, so even though you do have to manage your devices, there's a lot of support available. Note that LoRa is the underlying radio protocol and LoRaWAN is a higher level protocol on top. Thankfully you get a royalty-free LoRaWAN library support with the STM32WL series of chips.
Note that you don't have to use LoRa if you don't want (but we do suggest it, it's a great protocol!) You also get (G)FSK, (G)MSK and
BPSK - so you can communicate with 'basic' radio devices. Here's the radio deets
Frequency range: 150 MHz to 960 MHz
Modulation: LoRa, (G)FSK, (G)MSK, and BPSK
Transmitter high output power, programmable up to +22 dBm
Transmitter low output power, programmable up to +15 dBm
The frequency is 'programmable' from 150 to 960 MHz, but note that you have to have a front end for the radio where you tune the antenna section so you won't be able to change frequencies willy-nilly, you'll get the best performance at a narrow band range based on the available frequencies in your country!
Other nice things we saw in this chip: great low power numbers with 1uA draw with the RTC running, some hardware encryption support to help keep your data transmissions secret, RTC backup RAM, and a built in step-down/LDO to really squeeze that battery life. This chip would make an excellent LoRa node and at a really good price!
In particular, we liked the STM32WLE5C8U6 (https://www.digikey.com/en/products/detail/stmicroelectronics/STM32WLE5C8U6/13557439) in QFN which has 64Kb of FLASH and 20Kb of SRAM, which makes it easy to assemble, just enough capability to read some sensors and then send it over LoRaWAN and then go back to sleep, all for about $4 in qty (https://www.digikey.com/en/products/detail/stmicroelectronics/STM32WLE5C8U6/13557439) It's all based on the STM32L4 low-power series, so if you're familiar with the Cortex M4's from ST, you'll be able to slip into working with these chips fast.
Digi-Key has these chips in stock right now for immediate shipment, so you can order STM32WLE5C8U6 today and get started with your wireless product design tomorrow. (https://www.digikey.com/short/4tqtcj)