extern unsigned char uart_getchar_isr_noblock(char *returnval); // get a char from buffer if available
extern void uart_sendchar(char c); // blocking, no buffer
extern void uart_sendstr(char *s); // blocking, no buffer
extern unsigned char uart_getchar_isr_noblock(char *returnval); // get a char from buffer if available
extern void uart_sendchar(char c); // blocking, no buffer
extern void uart_sendstr(char *s); // blocking, no buffer