Hi Knud
Any sleep timer interrupts that are generated while the STIE or EA are disabled will not be seen by the CPU. The interrupt flags in the WOR register will be set, but STIF flag in the CPU will not be set and the ISR will never be run. It is therefore important not to disable interrupts while waiting for the sleep timer interrupt.
The reason we recommend not to use the sleep timer in active mode is that some compilers (IAR for example) will introduce code sequences, from its own low-level library, which disable global interrupts.
As long as you have full control over the code your compiler generates, and are sure that global interrupts are never disabled, you can use the SLEEP timer also in active mode.
BR
Siri
