C8051F52x-53x
Performance
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, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 25 MHz, it has a peak throughput of 25 MIPS. 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
2/4
5
3
3/5
7
4
5
5
2
4/6
1
6
2
8
1
Number of Instructions
26
50
10
Programming and Debugging Support
In-system programming of the Flash program memory and communication with on-chip debug support
logic is accomplished via the Silicon Labs 2-Wire (C2) interface. Note that the re-programmable Flash can
also be read and written a single byte at a time by the application software using the MOVC and MOVX
instructions. This feature allows program memory to be used for non-volatile data storage as well as updat-
ing program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints, starting, stopping and single stepping through program execution (including interrupt service
routines), examination of the program's call stack, and reading/writing the contents of registers and mem-
ory. This method of on-chip debugging is completely non-intrusive, requiring no RAM, Stack, timers, or
other on-chip resources.
The CIP-51 is supported by development tools from Silicon Laboratories, Inc. and third party vendors. Sili-
con Laboratories provides an integrated development environment (IDE) including editor, evaluation com-
piler, assembler, debugger and programmer. The IDE's debugger and programmer interface to the CIP-51
via the on-chip debug logic to provide fast and efficient in-system device programming and debugging.
Third party macro assemblers and C compilers are also available.
9.1. Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc-
tion set. Standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the stan-
dard 8051.
9.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take two less clock
cycles to complete when the branch is not taken as opposed to when the branch is taken. Table 9.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
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SILICON [ SILICON ]
