C8051F321-GMR Datasheet, PDF (18/250 Pages) Silicon Laboratories – Full Speed USB, 16 k ISP FLASH MCU Family

C8051F320/1
1.1. CIP-51™ Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051F320/1 family utilizes Silicon Labs' proprietary CIP-51 microcontroller core. The CIP-51 is fully
compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used
to develop software. The CIP-51 core offers all the peripherals included with a standard 8052, including
four 16-bit counter/timers, a full-duplex UART with extended baud rate configuration, an enhanced SPI
port, 2304 bytes of on-chip RAM, 128 byte Special Function Register (SFR) address space, and 25/21 I/O
pins.
1.1.2. Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the stan-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core exe-
cutes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than
four system clock cycles.
The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that
require each execution time.
Clocks to Execute
1
2
2/3
3
3/4
4
4/5
5
8
Number of Instructions 26
50
5
14
7
3
1
2
1
1.1.3. Additional Features
The C8051F320/1 SoC family includes several key enhancements to the CIP-51 core and peripherals to
improve performance and ease of use in end applications.
The extended interrupt handler provides 16 interrupt sources into the CIP-51 (as opposed to 7 for the stan-
dard 8051), allowing 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.
Nine reset sources are available: power-on reset circuitry (POR), an on-chip VDD monitor (forces reset
when power supply voltage drops below V_RST as given in Table 10.1 on page 105), the USB controller
(USB bus reset or a VBUS transition), a Watchdog Timer, a Missing Clock Detector, a voltage level detec-
tion from Comparator0, a forced software reset, an external reset pin, and an errant Flash read/write pro-
tection circuit. Each reset source except for the POR, Reset Input Pin, or Flash error may be disabled by
the user in software. The WDT may be permanently enabled in software after a power-on reset during
MCU initialization.
The internal oscillator is factory calibrated to 12 MHz ±1.5%, and the internal oscillator period may be user
programmed in ~0.25% increments. A clock recovery mechanism allows the internal oscillator to be used
with the 4x Clock Multiplier as the USB clock source in Full Speed mode; the internal oscillator can also be
used as the USB clock source in Low Speed mode. External oscillators may also be used with the 4x Clock
Multiplier. An external oscillator drive circuit is also included, allowing an external crystal, ceramic resona-
tor, capacitor, RC, or CMOS clock source to generate the system clock. The system clock may be config-
ured to use the internal oscillator, external oscillator, or the Clock Multiplier output divided by 2. If desired,
the system clock source may be switched on-the-fly between oscillator sources. An external oscillator can
be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) exter-
nal clock source, while periodically switching to the internal oscillator as needed.
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Rev. 1.4