Active Bluetooth 4.0 SoC with integrated MCU
The Texas Instruments CC2540F128RHAT is a single-chip Bluetooth 4.0 solution combining a 2.4 GHz transceiver with an integrated 8051-compatible MCU core. The radio delivers a -93 dBm receiver sensitivity and a +4 dBm maximum output power, supporting a 1 Mbps data rate over the Bluetooth v4.0 protocol.
Memory and I/O budget for BLE firmware
The 128 kB Flash must host both the BLE protocol stack and the application firmware. With a typical BLE 4.0 stack occupying 30–40 kB, roughly 90 kB remains for application code. The 8 kB SRAM handles stack data buffers and application variables; designs with large data arrays or multiple simultaneous connections should budget carefully. The 21 GPIO lines include serial interface pins shared with SPI, USART, and USB peripherals. When using USB, the D+ and D- pins consume two GPIOs, leaving 19 for general-purpose use. The SPI and USART interfaces share additional pins, so the actual free GPIO count depends on the peripheral configuration chosen.
The QFN is reworkable with hot air if the pad is properly tinned and the board has a solder mask defined pad; orientation is marked by a pin 1 chamfer on the package corner.