Advance Information
UM-TM57PA20&40_E
8 Bit Microcontroller
6
tenx technology, inc.
Preliminary
Rev 1.3, 2009/10/19
FUNCTIONAL DESCRIPTION
1. CPU Core
1.1 Clock Scheme and Instruction Cycle
The system clock is internally divided by two to generate Q1 state and Q2 state for each instruction
cycle. The Programming Counter (PC) is updated at Q1 and the instruction is fetched from program
ROM and latched into the instruction register in Q2. It is then decoded and executed during the
following Q1-Q2 cycle. Branch instructions take two cycles since the fetch instruction is ‘flushed’ from
the pipeline, while the new instruction is being fetched and then executed.
Fetch
Execute
Branch
Instruction
Instruction
Pipeline
Flow
Fetch
Execute
Fetch
Flush
Fetch
Execute
Instruction
Cycle
F
OSC
Q1
Q2
Q1
Q2
Q1
Q2
Q1
Q2
Q1
Q2
Q1
Q2
1.2 Addressing Mode
There are two Data Memory Planes in CPU, R-Plane and F-Plane. The registers in R-Plane are write-
only. The “MOVWR” instruction copy the W-register’s content to R-Plane registers by direct addressing
mode.
The lower locations of F-Plane are reserved for the SFR. Above the SFR is General Purpose Data
Memory, implemented as static RAM. F-Plane can be addressed directly or indirectly. Indirect
Addressing is made by INDF register. The INDF register is not a physical register. Addressing INDF
actually addresses the register whose address is contained in the FSR register (FSR is a pointer). The
first half of F-Plane is bit-addressable, while the second half of F-Plane is not bit-addressable.
R-Plane
F-Plane
00
00
SFR
Bit
Addressable
MOVWR
Instruction
1F
Write
Only 20
RAM
Bit Addressable
27
28
RAMBANK=0
RAMBANK=1
Bit Addressable
Bit Addressable
3F
3F
40
RAMBANK=0
RAMBANK=1
7F