MC68HC05L28B MOTOROLA [Motorola, Inc], MC68HC05L28B Datasheet - Page 51

• Manufacturer Part Number: MC68HC05L28B
• Description: Flexible general-purpose microcomputer
• Manufacturer: MOTOROLA [Motorola, Inc]

The MC68HC05L28 has a 15-stage ripple counter called the core timer (CTIMER). Features of this
timer are: timer overflow, power-on reset (POR), real time interrupt (RTI) with four selectable
interrupt rates, and a computer operating properly (COP) watchdog timer.
MC68HC05L28
8
8
Overflow
detect
CTOF RTIF CTOFE RTIE
circuit
f
OP
To interrupt logic
Interrupt circuit
/ 2
10
(Core timer control & status)
Figure 5-1 Core timer block diagram
(Core timer counter)
f
OP
$08 CTCSR
CORE TIMER
$09 CTCR
/ 2
17
0
CORE TIMER
RTI select circuit
Internal bus
0
5
RT1
7-bit counter
RT0
8
f
OP
/ 2
f
OP
14
Internal processor clock
/ 2
2
COP watchdog
( 4)
f
OP
timer
reset
( 8)
logic
To
POR
TCBP
MOTOROLA
Clear
COP
TPG
5-1
5