NXP Semiconductors MC9S08QL4, Reference Manual

Page: 164 / 240

Modulo Timer (S08MTIMV1)
MC9S08QL8 MCU Series Reference Manual, Rev. 1
164 NXP Semiconductors
12.1.3 Features
Timer system features include:
• 8-bit up-counter
— Free-running or 8-bit modulo limit
— Software controllable interrupt on overflow
— Counter reset bit (TRST)
— Counter stop bit (TSTP)
• Four software selectable clock sources for input to prescaler:
— System bus clock — rising edge
— Fixed frequency clock (XCLK) — rising edge
— External clock source on the TCLK pin — rising edge
— External clock source on the TCLK pin — falling edge
• Nine selectable clock prescale values:
— Clock source divide by 1, 2, 4, 8, 16, 32, 64, 128, or 256
12.1.4 Modes of Operation
This section defines the MTIM’s operation in stop, wait and background debug modes.
12.1.4.1 MTIM in Wait Mode
The MTIM continues to run in wait mode if enabled before executing the WAIT instruction. Therefore,
the MTIM can be used to bring the MCU out of wait mode if the timer overflow interrupt is enabled. For
lowest possible current consumption, the MTIM should be stopped by software if not needed as an
interrupt source during wait mode.
12.1.4.2 MTIM in Stop Modes
The MTIM is disabled in all stop modes, regardless of the settings before executing the STOP instruction.
Therefore, the MTIM cannot be used as a wakeup source from stop modes.
Waking from stop1 and stop2 modes, the MTIM will be put into its reset state. If stop3 is exited with a
reset, the MTIM will be put into its reset state. If stop3 is exited with an interrupt, the MTIM continues
from the state it was in when stop3 was entered. If the counter was active upon entering stop3, the count
will resume from the current value.
12.1.4.3 MTIM in Active Background Mode
The MTIM suspends all counting until the microcontroller returns to normal user operating mode.
Counting resumes from the suspended value as long as an MTIM reset did not occur (TRST written to a 1
or MTIMMOD written).