Problem with timeout

Hello everybody,  i have a problem when i use the timeout in a semaphore. I use EVK1100(AVR 32), freertos 1mseg tick, and i have written this code if( xSemaphoreTake(xSemaphoreReceived,1) == pdTRUE )
{
…..
} I have measured this time Timeout and it’s variable, never 1 mili second that i want.The obtained values  are 600microsecond, 400microsecond , 768microsecond anybody can help me? thanks
Oliver

Problem with timeout

A 1 ms tic rate means delays are only accurate to 1ms, and in fact, the way FreeRTOS works, the time out will expire in no more than the specified time, so a 1ms delay is 0-1ms, a 2 ms delay is 1-2ms, and so on. (The task may not start immediately on that next tick if some higher priority task is running). basically time steps in 1 ms intervals, so by its measure anything in “tick 10” is 1 tick before anything in “tick 11”, so a 1 tick delay means until the next tick, which might be almost a full tick in time if the interrupt just happended and might be almost no time if the tick interrupt is about ready to happen.

Problem with timeout

thank you very much Oliver