@wwh1260051266 @ia2018
There is an interesting blog about BLE and the M5Stack as well as some code for the M5Stack at the links below.
I haven't had a chance to try the code but it works for the writer.
Similarly, this code uses 75% of the flash memory. BLE must be greedy.
Blog: https://kongduino.wordpress.com/2018/01/17/basic-ble-functionality-on-the-m5stack/
Github: https://github.com/Kongduino/M5_BMP280