#52 UART buffer overruns

[Matthias Dyer]

We still have serious problems getting a reliable UART
communication when our system is under stress.

Symptomatic:
- Uart receive buffer overrun on Uart1

Reasons:
- ISR latency too large
. Uart0 (debug terminal) has higher priority than
Uart0 (BTmodule)
. long critical sections disable Interrupts too long
. ISR too time consuming/too complex

This Bug is also reported in this list as:
1063795 BT HCI UART Buffer Overrun @ 115200 baud
https://sourceforge.net/tracker/index.php?func=detail&aid=1063795&group_id=81773&atid=563977

1205562 reproducing (UART) buffer overruns with TestCase
https://sourceforge.net/tracker/index.php?func=detail&aid=1205562&group_id=81773&atid=563977

The bug relates to the UART driver in NutOS
(http://sourceforge.net/projects/ethernut/)