UART1 with RX interrupts that send the received byte back through UART TX
RX interrupt working
printf working
Added FIFO and associated functions
USARTs 1 and 6 both working
Added printf.c for mapping to our host_send_char function
Make USART6 (to host) TX only, USART1 (to Piksi) RX only
Add libswiftnav as submodule
Changes to work with -std=gnu99
Keep linker from barfing on multiple definitions of _impure_ptr with gnu99. This is probably not a good way of doing this, should be changed in the future.
Receiving SBP messages from Piksi on UART1 and reporting sender id and length through UART6.
Change printf to use syscalls _write
Receiving and printing 5 messages
Add sbp_tutorial.h/.c for functions that are implementation specific, to keep main.c simple.
Rename sbp_tutorial to tutorial_implementation. Add more comments.
Add copyright and license headers
Add LGPL license file
Clean up comments