Motorola MC68HC908AB32 User Manual

System Integration Module (SIM)
Reset and System Initialization
MC68HC908AB32 — Rev. 1.0 Technical Data
MOTOROLA System Integration Module (SIM) 115
Figure 8-5. Internal reset timing
The COP reset is asynchronous to the bus clock.
Figure 8-6. Sources of Internal Reset
The active reset feature allows the part to issue a reset to peripherals
and other chips within a system built around the MCU.
8.4.2.1 Power-On Reset
When power is first applied to the MCU, the power-on reset module
(POR) generates a pulse to indicate that power-on has occurred. The
external reset pin (RST
) is held low while the SIM counter counts out
4096 CGMXCLK cycles. 64 CGMXCLK cycles later, the CPU and
memories are released from reset to allow the reset vector sequence to
occur.
At power-on, the following events occur:
• A POR pulse is generated
• The internal reset signal is asserted
• The SIM enables CGMOUT
• Internal clocks to the CPU and modules are held inactive for 4096
CGMXCLK cycles to allow the oscillator to stabilize
IRST
RST
RST PULLED LOW BY MCU
IAB
32 CYCLES 32 CYCLES
VECTOR HIGH
CGMXCLK
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
LVI
POR
INTERNAL RESET

Motorola MC68HC908AB32 Specifications

General

Brand	Motorola
Model	MC68HC908AB32
Category	Controller
Language	English