Unlocking the Potential of the SR08 Smart Ring: A Deep Dive into Custom Firmware Flashing
0:00:02 Introduction to the SR08 Smart Ring: The SR08 is a Bluetooth Low Energy (BLE) enabled smart ring designed for fitness tracking, heart rate monitoring, and time display.
0:00:28 Hardware Specifications: It features a Dialog DA14584 microcontroller with 96KB of OTP memory and an external 1MB flash memory for firmware storage and over-the-air (OTA) updates.
0:01:38 Challenges of Custom Firmware Development: Flashing custom firmware is complex due to the Dialog DA14584's development cycle and the need for a specific development board. The presenter broke three rings attempting this. Debug access within the ring is also not readily available.
0:02:28 Development Board Recommendation: For custom firmware development, a Dialog DA14584 development board (now Renesas, costing around 35 euros) is recommended. The presenter had to replace the stock 256KB SPI flash on the board with a 1MB version to match the ring's hardware.
0:03:16 Custom Firmware Resources: A GitHub repository is available with pre-compiled demo firmware, stock firmware, data sheets, pinout information, and tools for creating OTA headers and flashing the modified bootloader.
0:03:55 OTA Update Process: Using the Renesas "SUOTA" app, users can connect to the ring, select the desired firmware (stock or custom), and initiate the update process.
0:05:05 CRC Error Workaround: The ring manufacturer modified the OTA update process, causing a CRC error in the SUOTA app. This error can be safely ignored.
0:05:41 Custom Firmware Functionality: The custom firmware enables basic display and touch sensor control, drawing 3mA when active and 18-19Β΅A in sleep mode.
0:06:56 Restoring Stock Firmware: The stock firmware can be restored using the SUOTA app and selecting the original firmware file.
0:08:33 Conclusion: While the presenter is excited about the potential of custom firmware, the challenging development process led them to halt further development and encourage others to continue the work.
0:08:51 Call to Action: Developers interested in creating custom firmware are encouraged to obtain a development board and explore the possibilities.