Reset Initial Conditions - Holtek HT45F23A Manual

HT45F23A/HT45F24A
TinyPower Flash MCU with OPA & Comparators
TM

Reset Initial Conditions

The different types of reset described affect the reset flags in different ways. These flags, known
as PDF and TO are located in the status register and are controlled by various microcontroller
operations, such as the SLEEP or IDLE Mode function or Watchdog Timer. The reset flags are
shown in the table:
TO
0
u
1
1
The following table indicates the way in which the various components of the microcontroller are
affected after a power-on reset occurs.
Program Counter
Interrupts
WDT
Timer/Event Counter
Input/Output Ports
Stack Pointer
The different kinds of resets all affect the internal registers of the microcontroller in different ways.
To ensure reliable continuation of normal program execution after a reset occurs, it is important to
know what condition the microcontroller is in after a particular reset occurs. The following table
describes how each type of reset affects each of the microcontroller internal registers. Note that
where more than one package type exists the table will reflect the situation for the larger package
type.
Rev. 1.40
PDF
0 Power-on reset
u RES or LVR reset during NORMAL or SLOW Mode operation
u WDT time-out reset during NORMAL or SLOW Mode operation
1 WDT time-out reset during IDLE or SLEEP Mode operation
Item
Reset to zero
All interrupts will be disabled
Clear after reset, WDT begins counting
Timer Counter will be turned off
I/O ports will be setup as inputs
Stack Pointer will point to the top of the stack
57
RESET Conditions
Note: "u" stands for unchanged
Condition After RESET
March 29, 2019