The STM32 connectivity line is available in two variants. The features common to both variants include: up to 256kB of Flash; multiple communication peripherals - USART, SPI, and I2C; multiple 16-bit timers; two 12-bit DACs; an Embedded Trace Module that provides comprehensive debug and trace facilities for ARM processors; a 3 ~ 25MHz main oscillator and internal 8MHz and 40kHz RC oscillators; Real Time Clock; two Watchdog timers; reset circuitry; two 12-bit ADCs; PWM timer; DMA with up to 12 channels; and an 80% GPIO ratio.