STM32 Architecture STM32F401RE, mbed-Enabled Development Nucleo-64 STM32F4 ARM® Cortex®-M4 MCU 32-Bit Embedded Evaluation Board 3x USARTs running at up to 10.5 Mbit/s, 4x SPI running at up to 42 Mbit/s, 3x I²C, 1x SDIO, 1x USB 2.0 OTG full speed, 2x full duplex I²S up to up to 32-bit/192KHz, 12-bit ADC reaching 2.4 MSPS, 10 timers, 16- and 32-bit, running at up to 84 MHz