MC68HC908LB8_05 Datasheet, PDF (171/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Chapter 17
System Integration Module (SIM)
17.1 Introduction
This section describes the system integration module (SIM). Together with the central processor unit
(CPU), the SIM controls all microcontroller unit (MCU) activities. A block diagram of the SIM is shown in
Figure 17-1. Table 17-1 is a summary of the SIM input/output (I/O) registers. The SIM is a system state
controller that coordinates CPU and exception timing.
The SIM is responsible for:
• Bus clock generation and control for CPU and peripherals:
– Stop/wait/reset/break entry and recovery
– Internal clock control
• Master reset control, including power-on reset (POR) and computer operating properly (COP)
timeout
• Interrupt control:
– Acknowledge timing
– Arbitration control timing
– Vector address generation
• CPU enable/disable timing
• Modular architecture expandable to 128 interrupt sources
Table 17-1 shows the internal signal names used in this section.
MC68HC908LB8 Data Sheet, Rev. 1
Freescale Semiconductor
171