The BT900 provides for multiple hardware interfaces including UART host interface, 18 configurable GPIO lines, I²C interface and SPI (1 each configurable from GPIO total), ADC interface (teo channels configured from GPIO total), and three dedicated pins for Wi-Fi and Bluetooth coexistence. The BT900 module architecture incorporates the CSR 8811 silicon chipset and a low power Cortex M3 microcontroller.