Datasheet

MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
Freescale Semiconductor 111
Chapter 9
System Integration Module (SIM)
9.1 Introduction
This chapter describes the system integration module (SIM), which supports up to 32 external and/or
internal interrupts. Together with the central processor unit (CPU), the SIM controls all MCU activities. A
block diagram of the SIM is shown in Figure 9-1. Figure 9-2 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