Set the sleep timer to 1s and sleep 10 times, so you have your required 10s.
Thank you for your question... The sleeptimer is a opcion, but the homework requires a M8C_Sleep instruction, desafortunatly
This shows basics of how to use various resources to control wakeup
If you need extended time in sleep, there are several approaches you could use.
1) Sleep timer set to 1 sec, wake up 10 times, effectively you have slept 10 S.
2) Use RC network and comparator interrupt to generate 10 S wakep interrupt.
3) Digital blocks clcoked by ILO, so use a "wide" timer or counter to generate