SM39R08A5
8-Bit Micro-controller
with 8KB Flash
& 256B RAM embedded
01
10
11
Fosc
Fosc/2
Fosc/4
1.5. RESET
1.5.1. Hardware RESET function
SM39R08A5 provides on-chip hardware RESET mechanism,，the reset duration is programmable by writer or ICP。
on-chip hardware RESET duration
25ms (default)
200ms
100ms
50ms
16ms
8ms
4ms
1.5.2. Software RESET function
SM39R08A5 provides one software reset mechanism to reset whole chip. To perform a software reset, the firmware must
write three specific values 55h, AAh and 5Ah sequentially to the TAKEY register to enable the Software Reset register
(SWRES) write attribute. After SWRES register obtain the write authority, the firmware can write FFh to the SWRES
register. The hardware will decode a reset signal that “OR” with the other hardware reset. The SWRES register is
self-reset at the end of the software reset procedure.
Mnemonic
TAKEY
SWRES
Description
Time Access Key register
Software Reset register
Direct Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
Software Reset function
F7h
TAKEY [7:0]
E7h
SWRES [7:0]
Bit 1
Bit 0
RESET
00H
00H
1.5.3. Reset status
Mnemonic: RSTS
7
6
-
-
5
-
4
PDRF
3
WDTF
2
SWRF
1
LVRF
Address: A1h
0
Reset
PORF
00H
PDRF: Pad reset flag.
When MCU is reset by reset pad, PDRF flag will be set to one by hardware. This flag
clear by software.
WDTF: Watchdog timer reset flag.
When MCU is reset by watchdog, WDTF flag will be set to one by hardware. This flag
clear by software.
SWRF: Software reset flag.
When MCU is reset by software, SWRF flag will be set to one by hardware. This flag
clear by software.
LVRF: Low voltage reset flag.
When MCU is reset by LVR, LVRF flag will be set to one by hardware. This flag clear by
software.
PORF: Power on reset flag.
When MCU is reset by POR, PORF flag will be set to one by hardware. This flag clear
by software.
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M067
Ver B SM39R08A5 04/22/2013
- 11 -
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
