st10f272z2 STMicroelectronics, st10f272z2 Datasheet - Page 48

• Manufacturer Part Number: st10f272z2
• Description: 16-bit Mcu With 256 Kbyte Flash Memory And 20 Kbyte Ram
• Manufacturer: STMicroelectronics

Central processing unit (CPU)
7
Figure 7.
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256K Byte
memory
Flash
Central processing unit (CPU)
The CPU includes a 4-stage instruction pipeline, a 16-bit arithmetic and logic unit (ALU) and
dedicated SFRs. Additional hardware has been added for a separate multiply and divide
unit, a bit-mask generator and a barrel shifter.
Most of the ST10F272Z2 instructions can be executed in one instruction cycle which
requires 31.25 ns at 64 MHz CPU clock. For example, shift and rotate instructions are
processed in one instruction cycle independent of the number of bits to be shifted.
Multiple-cycle instructions have been optimized: branches are carried out in 2 cycles, 16 x
16-bit multiplication in 5 cycles and a 32/16-bit division in 10 cycles.
The jump cache reduces the execution time of repeatedly performed jumps in a loop, from
2 cycles to 1 cycle.
The CPU uses a bank of 16 word registers to run the current context. This bank of General
Purpose Registers (GPR) is physically stored within the on-chip Internal RAM (IRAM) area.
A Context Pointer (CP) register determines the base address of the active register bank to
be accessed by the CPU.
The number of register banks is only restricted by the available Internal RAM space. For
easy parameter passing, a register bank may overlap others.
A system stack of up to 2048 bytes is provided as a storage for temporary data. The system
stack is allocated in the on-chip RAM area, and it is accessed by the CPU via the stack
pointer (SP) register.
Two separate SFRs, STKOV and STKUN, are implicitly compared against the stack pointer
value upon each stack access for the detection of a stack overflow or underflow.
CPU block diagram (MAC Unit not included)
32
Exec. Unit
BUSCON 0
BUSCON 1
BUSCON 2
BUSCON 3
BUSCON 4
Data Pg. Ptrs
Instr. Ptr
STKUN
SYSCON
STKOV
Pipeline
PSW
4-Stage
SP
ADDRSEL 1
ADDRSEL 2
ADDRSEL 3
ADDRSEL 4
Code Seg. Ptr.
Bit-Mask Gen.
Mul./Div.-HW
Barrel-Shift
CPU
16-Bit
MDH
MDL
ALU
CP
Registers
General
Purpose
R15
R0
16
16
2K Byte
Internal
Bank
Bank
Bank
ST10F272Z2
RAM
n
0
i