mc68hc05pl4b Freescale Semiconductor, Inc, mc68hc05pl4b Datasheet - Page 14

• Manufacturer Part Number: mc68hc05pl4b
• Description: Low-cost Single-chip Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

GENERAL RELEASE SPECIFICATION
1.4
1.4.1 VDD, VSS
1.4.2 OSC1, OSC2
1.4.3 RESET
1.4.4 LED/IRQ
1-4
PIN DESCRIPTIONS
The following paragraphs give a description of each functional pin.
Power is supplied to the MCU using these pins. VDD is the positive supply and
VSS is the ground pin.
OSC2 is only available on MC68HC05PL4B.
The OSC1 and OSC2 pins are the connections for the on-chip oscillator — the
following con gur ations are available:
The external oscillator clock frequency, f
internal operating frequency, f
This active low input-only pin is used to reset the MCU to a known start-up state.
The RESET pin has an Schmitt trigger circuit as part of its input to improve noise
immunity.
This pin has two functions, con gured b y the IRQEN bit in the Miscellaneous Con-
trol and Status Register, at $1C (MISCR).
When this pin is IRQ, it drives the asynchronous IRQ interrupt function of the
CPU. The IRQ interrupt function uses the IRQS bit in the MISCR to provide either
only negative edge-sensitive triggering or both negative edge-sensitive and low
level-sensitive triggering. If the MISCR bit is set to enable level-sensitive
1. A crystal or ceramic resonator as shown in Figure 1-4(a).
2. An external clock signal as shown in Figure 1-4(b).
(a) Crystal or
OSC1
Ceramic Resonator
Connections
2 M
MCU
Freescale Semiconductor, Inc.
OSC2
For More Information On This Product,
Figure 1-4. Oscillator Connections
Go to: www.freescale.com
GENERAL DESCRIPTION
OP
April 30, 1998
.
OSC
, is divided by two to produce the
OSC1
(c) External
EXTERNAL CLOCK
MCU
UNCONNECTED
Clock Source
Connection
OSC2
MC68HC05PL4
REV 2.0