C8051F02X Datasheet, PDF (23/272 Pages) Silicon Laboratories – 8K ISP FLASH MCU Family

C8051F020/1/2/3
1.1.3. Additional Features
The C8051F020 MCU family includes several key enhancements to the CIP-51 core and peripherals to improve over-
all performance and ease of use in end applications.
The extended interrupt handler provides 22 interrupt sources into the CIP-51 (as opposed to 7 for the standard 8051),
allowing the numerous analog and digital peripherals to interrupt the controller. An interrupt driven system requires
less intervention by the MCU, giving it more effective throughput. The extra interrupt sources are very useful when
building multi-tasking, real-time systems.
There are up to seven reset sources for the MCU: an on-board VDD monitor, a Watchdog Timer, a missing clock
detector, a voltage level detection from Comparator0, a forced software reset, the CNVSTR input pin, and the /RST
pin. The /RST pin is bi-directional, accommodating an external reset, or allowing the internally generated POR to be
output on the /RST pin. Each reset source except for the VDD monitor and Reset Input pin may be disabled by the
user in software; the VDD monitor is enabled/disabled via the MONEN pin. The Watchdog Timer may be perma-
nently enabled in software after a power-on reset during MCU initialization.
The MCU has an internal, stand alone clock generator which is used by default as the system clock after any reset. If
desired, the clock source may be switched on the fly to the external oscillator, which can use a crystal, ceramic reso-
nator, capacitor, RC, or external clock source to generate the system clock. This can be extremely useful in low power
applications, allowing the MCU to run from a slow (power saving) external crystal source, while periodically switch-
ing to the fast (up to 16 MHz) internal oscillator as needed.
Figure 1.6. On-Board Clock and Reset
VDD
(Port
I/O)
CP0+
CP0-
XTAL1
XTAL2
Crossbar
CNVSTR
(CNVSTR
reset
enable)
Comparator0
+
-
(CP0
reset
enable)
Supply
Monitor
+
-
Supply
Reset
Timeout
Internal
Clock
Generator
OSC
Missing
Clock
Detector
(one-
shot)
EN
WDT
EN PRE
System
Clock
Clock Select
CIP-51
Software Reset
Microcontroller
Core
System Reset
Extended Interrupt
Handler
(wired-OR)
Reset
Funnel
/RST
Rev. 1.4
23