HT46R74D-1 Holtek Semiconductor, HT46R74D-1 Datasheet - Page 17

• Manufacturer Part Number: HT46R74D-1
• Description: Dual Slope A/D Type MCU
• Manufacturer: Holtek Semiconductor

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Reset
There are three ways in which a reset may occur.
The WDT time-out during a HALT or IDLE differs from other
reset conditions, as it performs a warm reset that resets
only the program counter and SP and leaves the other cir-
cuits in their original state. Some registers remain unaf-
fected during any other reset conditions. Most registers are
reset to their initial conditions once the reset conditions are
met. By examining the PDF and TO flags, the program can
distinguish between different reset types.
Note: u stands for unchanged
To guarantee that the system oscillator has started and has
stabilised, the SST (System Start-up Timer) provides an
extra-delay of 1024 system clock pulses when the system
awakes from the Power-down mode or during power-up.
When awakening from the Power-down mode or during a
system power-up, the SST delay is added.
The functional unit chip reset status is shown below.
Rev. 1.10
Program Counter
Interrupt
Prescaler, Divider
WDT
Timer/Event Counter
Input/output Ports
Stack Pointer
TO PDF
RES is reset during a normal operation
RES is reset during Power-down
WDT time-out is reset during normal operation
0
u
0
1
1
0
u
1
u
1
RES reset during power-up
RES reset during normal operation
RES Wake-up HALT
WDT time-out during normal operation
WDT Wake-up HALT
RESET Conditions
000H
Disabled
Cleared
Cleared. After master reset,
WDT starts counting
Off
Input mode
Points to the top of the stack
17
Note:
nected to the RES pin as short as possible, to
avoid noise interference.
* Make the length of the wiring, which is con-
Reset Configuration
Reset Timing Chart
Reset Circuit
HT46R74D-1
January 11, 2007