BLE SoC with 256 kB Flash — the firmware headroom question
The Texas Instruments CC2541F256RHAR is a single-chip Bluetooth v5.0-compliant transceiver with a 2.4 GHz radio and 256 kB Flash plus 8 kB RAM on a single die. This is the high-density Flash variant of the CC2541 family, which matters when the application code plus BLE stack and OTA update staging area must fit without external memory. The 23 GPIOs give enough headroom for a sensor hub or beacon with a handful of peripherals — I²C, SPI, and USART interfaces are on board for external sensors or displays.
-99 dBm sensitivity at 2 Mbps — what the link budget buys
The receiver sensitivity of -99 dBm at the maximum 2 Mbps data rate is the figure that sets the usable range in a BLE link. At 0 dBm transmit power, the path loss budget runs about 99 dB before the link drops. The modulation options — GFSK and MSK — let you trade off data rate against interference robustness; GFSK is the standard BLE choice for most applications.
Current draw sits at 17.9 mA to 20.2 mA receiving and 16.8 mA to 18.2 mA transmitting.