SainSmart STM32F103RBT6 ARM Cortex-M3 mini Development Board+Code chip board STM32F103RBT6, board JTAG interface and reset button the onboard crystal 32.768KHZ and 8MHZ,with a 5V chip, 3.3V AMS1117-3.3 switch with a RS232 serial port, UART1 and UART2 can be set by jumper all I / O all the leads, and mark the I / O name,supports USB power supply and power supply JLink Power On board size 71 (mm) * 99 (mm)