Motorola MC68HC908AB32 - Introduction

System Integration Module (SIM)
Technical Data MC68HC908AB32 — Rev. 1.0
110 System Integration Module (SIM) MOTOROLA
8.8 SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
8.8.1 SIM Break Status Register. . . . . . . . . . . . . . . . . . . . . . . . .127
8.8.2 SIM Reset Status Register. . . . . . . . . . . . . . . . . . . . . . . . .128
8.8.3 SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . .129
8.2 Introduction
This section describes the system integration module (SIM), which
supports up to 24 external and/or internal interrupts. Together with the
CPU, the SIM controls all MCU activities. A block diagram of the SIM is
shown in Figure 8-1. Figure 8-2 is a summary of the SIM 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 COP
timeout
• Interrupt control:
– Acknowledge timing
– Arbitration control timing
– Vector address generation
• CPU enable/disable timing
• Modular architecture expandable to 128 interrupt sources
Table 8-1 shows the internal signal names used in this section.