mc68hc705v12 Freescale Semiconductor, Inc, mc68hc705v12 Datasheet - Page 89

• Manufacturer Part Number: mc68hc705v12
• Description: M68hc05-based Mcu Hc05 Freescale Semiconductor
• Manufacturer: Freescale Semiconductor, Inc

8.3 Core Timer Status and Control Register
MC68HC705V12
—
Rev. 3.0
Address:
The core timer status and control register (CTSCR) contains:
Figure 8-2
of reset.
CTOF — Core Timer Overflow Bit
RTIF — Real Time Interrupt Flag
Reset:
Read:
Write:
Figure 8-2. Core Timer Status and Control Register (CTSCR)
•
•
•
CTOF is a read-only status bit set when the 8-bit ripple counter rolls
over from $FF to $00. Clearing the CTOF is done by writing a 1 to
TOFC. Writing to this bit has no effect. Reset clears CTOF.
The real-time interrupt circuit consists of a 3-stage divider and a
1-of-4 selector. The clock frequency that drives the RTI circuit is
E/2**11 (or E/2048) with three additional divider stages giving a
maximum interrupt period of 7.8 milliseconds at a bus rate of 2.1 MHz.
RTIF is a clearable, read-only status bit and is set when the output of
the chosen (1-of-4 selection) stage goes active. Clearing the RTIF is
done by writing a 1 to RTFC. Writing has no effect on this bit. Reset
clears RTIF.
Freescale Semiconductor, Inc.
For More Information On This Product,
Timer interrupt flag
Timer interrupt enable bits
Real-time interrupt rate select bits
$0008
CTOF
Bit 7
0
shows the value of each bit in the CTSCR when coming out
Go to: www.freescale.com
= Unimplemented
RTIF
6
0
Core Timer
TOFE
5
0
RTIE
4
0
Core Timer Status and Control Register
TOFC
3
0
0
RTFC
2
0
0
Advance Information
RT1
1
1
Core Timer
Bit 0
RT0
1