Pebble switches from Nordic to SiFli bluetooth MCU: https://www.cnx-software.com/2025/05/14/sifli-sf32lb52j-big-little-arm-cortex-m33-bluetooth-mcu-powers-the-core-time-2-smartwatch/
Honestly it's an eye-opener about how quickly that chinese fabless semiconductor companies are moving. The SF32 SDK is pretty impressive at a glance. I'm still seeing a chunk of the bluetooth stack buried in a binary blob, but almost everything else is open source.
SiFli SF32LB52J big.LITTLE Arm Cortex-M33 Bluetooth MCU powers the Core Time 2 smartwatch
SiFli SF23LB52J is a Bluetooth 5.3 microcontroller part of the SF32LB52x family with two Cortex-M33 in big.LITTLE configuration with a 240 MHz high-performance core for user application/GUI and a 24 MHz low-power core to manage the Bluetooth part. A few months ago, Eric Migicovsky, the founder of the smartwatch company Pebble, and now Core Devices, introduced the Core 2 Duo and Core Time 2 smartwatches running PebbleOS open-source firmware that were mostly relaunches of the never-released Pebble 2 and Pebble Time 2 with some tweaks. We already knew the Core 2 Duo would be based on a Nordic nRF52840 Arm Cortex-M4F microcontroller, however, the one for the Core Time 2 was kept secret. That's until today, as Eric has just announced that the Core Time 2 would be based on the SiFli SF23LB52J MCU, since the smartwatch required an MCU with more RAM and processing power, and SiFli also offers