MC68HC908GT16_07 Datasheet, PDF (179/292 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 15
System Integration Module (SIM)
15.1 Introduction
This section describes the system integration module (SIM). Together with the central processor unit
(CPU), the SIM controls all microconroller unit (MCU) activities. A block diagram of the SIM is shown in
Figure 15-1. Table 15-1 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 arbitration
Table 15-1 shows the internal signal names used in this section.
Signal Name
CGMXCLK
CGMOUT
IAB
IDB
PORRST
IRST
R/W
Table 15-1. Signal Name Conventions
Description
Selected clock source from internal clock generator module (ICG)
Clock output from ICG module
(Bus clock = CGMOUT divided by two)
Internal address bus
Internal data bus
Signal from the power-on reset module to the SIM
Internal reset signal
Read/write signal
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
Freescale Semiconductor
179