Advance Information
UM-TM57PA20&40_E
8 Bit Microcontroller
9
tenx technology, inc.
Preliminary
Rev 1.3, 2009/10/19
2. Chip Operation Mode
2.1 Reset
The device can be RESET in four ways.
-
Power-On-Reset
-
Low Voltage Reset (LVR)
-
External Pin Reset(PA7)
-
Watchdog Reset (WDT)
After Power-On-Reset, all system and peripheral control registers are then set to their default hardware
Reset values. And the clock source, LVR level and chip operation mode are selected by the SYSCFG
register value.
The Low Voltage Reset features static reset when supply voltage is below a threshold level. There are
two threshold levels can be selected. The LVR’s operation mode is defined by the SYSCFG register.
The External Pin Reset and Watchdog Reset can be disabled or enabled by the SYSCFG register. These
two resets also set all the control registers to their default reset value. The TO/PD flag is not affected by
these resets.
2.2 System Configuration Register (SYSCFG)
The System Configuration Register (SYSCFG) is located at ROM address FFCh. The SYSCFG
determines the option for initial condition of MCU. It is written by PROM Writer only. User can select clock
source, LVR threshold voltage and chip operation mode by SYSCFG register. The 13th bit of SYSCFG is
code protection selection bit. If this bit is 0, the data in PROM will be protected, when user read PROM.
Bit 13~0
Default Value
11_1111_111x_xxxx
Bit Description
13
nPROTECT
: Code Protection Selection
1
No
protect
0
Code
protection
12
nREUSE
: PROM Re-use Control
1
Not
Re-use
0
Re-use (TM57PA20 do not support)
11-10
LVR
: LV reset mode
11
LVR threshold is 2.1V, always enable
10
LVR threshold is 2.1V, disable in sleep mode
01
LVR threshold is 3.1V, always enable
00
LVR
disable
9-8
CLKS
: Clock Source Selection
11
Fast Xtal (455KHz~24MHz)
10
Slow Xtal (32KHz)
01
Internal RC (4MHz)
00
External
RC
7
XRESETE
: External pin Reset Enable
1
Enable External pin Reset
0
Disable External pin Reset
6
WDTE
: WDT Reset Enable
1
Enable WDT Reset, Disable WKT Timer
0
Disable WDT Reset, Enable WKT Timer
4-0
IRCF
: Internal RC Frequency adjustment control