HT82B40A HOLTEK [Holtek Semiconductor Inc], HT82B40A Datasheet - Page 25

• Manufacturer Part Number: HT82B40A
• Description: I/O MCU with USB Interface
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

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 Power
Down function or Watchdog Timer. The reset flags are
shown in the table:
Note: u stands for unchanged
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 the microcontroller in-
ternal registers.
Rev. 1.10
TO PDF
MP0
MP1
BP
ACC
PCL
TBLP
TBLH
WDTS
STATUS
INTC
TMR0
TMR0C
TMR1H
TMR1L
TMR1C
PA
PAC
PB
PBC
PC
PCC
0
0
0
1
1
Register
0
0
0
u
1
RES reset during power-on
RES wake-up during Power Down
RES or LVR reset during normal operation
WDT time-out reset during normal operation
WDT time-out reset during Power Down
(Power-on)
0000 0000
1000 0111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
xxxx xxxx
--00 xxxx
00-0 1---
00-0 1---
0000H
Reset
RESET Conditions
WDT Time-out
Operation)
0000 0000
uuuu uuuu
uuuu uuuu
uuuu uuuu
1000 0111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
--1u uuuu
xxxx xxxx
xxxx xxxx
xxxx xxxx
(Normal
00-0 1---
00-0 1---
0000H
RES Reset
Operation)
0000 0000
uuuu uuuu
uuuu uuuu
uuuu uuuu
1000 0111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
--00 uuuu
xxxx xxxx
xxxx xxxx
xxxx xxxx
00-0 1---
00-0 1---
(Normal
0000H
25
The following table indicates the way in which the vari-
ous components of the microcontroller are affected after
a power-on reset occurs.
RES Reset
Program Counter
Interrupts
WDT
Timer/Event
Counter
Prescaler
Input/Output Ports I/O ports will be setup as inputs
Stack Pointer
0000 0000
uuuu uuuu
uuuu uuuu
uuuu uuuu
1000 0111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
--00 uuuu
xxxx xxxx
xxxx xxxx
xxxx xxxx
00-0 1---
00-0 1---
(HALT)
0000H
Item
uuuu uuuu
uuuu uuuu
00u0 00uu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
-uuu uuuu
Time-out
--11 uuuu
uu-u u---
uu-u u---
(HALT)*
0000H
WDT
HT82B40R/HT82B40A
Reset to zero
All interrupts will be disabled
Clear after reset, WDT begins
counting
Timer Counter will be turned off
The Timer Counter Prescaler will
be cleared
Stack Pointer will point to the top
of the stack
Condition After RESET
USB Reset
0000 0000
uuuu uuuu
uuuu uuuu
uuuu uuuu
1000 0111
uuuu uuuu
uuuu uuuu
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
--uu uuuu
xxxx xxxx
(Normal)
uu-u u---
uu-u u---
0000H
September 4, 2009
USB Reset
0000 0000
uuuu uuuu
uuuu uuuu
uuuu uuuu
1000 0111
uuuu uuuu
uuuu uuuu
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
1111 1111
-000 0000
xxxx xxxx
xxxx xxxx
--01 uuuu
xxxx xxxx
uu-u u---
uu-u u---
(HALT)
0000H