title: STM32F4 waveshare xcore407l doesn't work on ubuntu
body: <p>During three days I try to program and flash my STM32F4 waveshare xcore407l development board (bought on amazon) but I cannot do it.It doesn't work I tried to flash it with stm32flash and st-flash but I get some error.
  When I try with stm32flash (stm32flash -w test.bin -v -g 0x8000000 /dev/ttyS0) I get output error like :</p>
  
  <pre><code>Using Parser : Raw BINARY
  Warning: Not a tty: /dev/ttyS0
  Error probing interface "serial_posix"
  Cannot handle device "/dev/ttyS0"
  Failed to open port: /dev/ttyS0
  </code></pre>
  
  <p>with st-flash (st-flash write v1 test.bin  0x8000000) I get this:</p>
  
  <pre><code>2016-04-16T16:47:39 WARN src/stlink-sg.c: Failed to find an stlink v1 by VID:PID
  2016-04-16T16:47:39 ERROR src/stlink-sg.c: Could not open stlink device
  </code></pre>
  
  <p>if someone has already worked on this development board thanks to tell me how you did it. 
  Pending your answers I wish you good day</p>