[En-Nut-Discussion] Strange slowdown

[Tom Nyström]

Hello all!
 
We are using an Ethernut to control a hydraulic valve. Four Phase and frequency correct PWM signals are
generated (output A and C on Timers 1 and 3). Communication is handled mainly over IP with
some broadcasts over UART for monitoring. This worked fine until recently, when the IP communication
slowed down considerably. We were very confused since we haven't made any major changes in our code.
After some testing it was discovered that if Timer 3 is set to Fast PWM instead, everything works
normally. Timer 1 can operate in any PWM mode. Only the IP communication seems to be affected - 
not the other processes. When a command finally reaches the processor, it is handled without delay.
 
Does anyone know why this happens? I haven't attached our code since its quite large. If anyone wants to
look at it I can mail directly.
 
We are using NutOS 3.01 and avr-gcc 3.3 20030113.
 
Regards
Tom Nyström