SM39R08A5
8-Bit Micro-controller
with 8KB Flash
& 256B RAM embedded
Function Description
1. General Features
SM39R08A5 is an 8-bit micro-controller. All of its functions and the detailed meanings of SFR will be given in the following
sections.
1.1. Embedded Flash
The program can be loaded into the embedded 8KB Flash memory via its writer. The high-quality Flash has a 100K-write
cycle life, suitable for re-programming and data recording as EEPROM.
1.2. IO Pads
The SM39R08A5 has an I/O port: Port 3. Port 3 is 8-bit port. These are: quasi-bidirectional (standard 8051 port outputs),
push-pull, open drain, and input-only. As described in section 5.
The RESET Pin can be configured as I/O port P3.6, when the user uses on-chip hardware RESET mechanism.
1.3. Instruction timing Selection
The conventional 52-series MCUs are 12T, i.e., 12 oscillator clocks per machine cycle. SM39R08A5 is a 1T to 8T MCU,
i.e., its machine cycle is one-clock to eight-clock. In the other words, it can execute one instruction within one clock to only
eight clocks.
Mnemonic: CKCON
7
6
5
-
ITS
Address: 8Eh
1
0
Reset
CLKOUT
10H
4
3
-
2
-
ITS: Instruction timing select.
ITS [6:4]
Instruction timing
000
1T mode
001
2T mode (default)
010
3T mode
011
4T mode
100
5T mode
101
6T mode
110
7T mode
111
8T mode
The default is in 2T mode, and it can be changed to another Instruction timing mode if CKCON [6:4] (at address 8Eh) is
change any time. Not every instruction can be executed with one machine cycle. The exact machine cycle number for all
the instructions are given in the next section.
1.4. The Clock Output Selection
The SM39R08A5 can generate a clock output signal at P3.5. The CKCON [1:0] (at address 8Eh) can change any time.
CLKOUT: Clock output select.
CKCON [1:0]
Mode.
00
GPIO (P3.5)
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M067
Ver B SM39R08A5 04/22/2013
- 10 -
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
