HT98R068-1_13 Datasheet, PDF (41/116 Pages) Holtek Semiconductor Inc – Two Way Radio 8-Bit MCU

HT98R068-1
Two Way Radio 8-Bit MCU
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 Idle/Sleep function or Watchdog Timer. The reset flags are shown in the
table:
TO
PDF
RESET Conditions
0
0
Power-on reset
u
u
RES or LVR reset during Normal or Slow Mode operation
1
u
WDT time-out reset during Normal or Slow Mode operation
1
1
WDT time-out reset during Idle or Sleep Mode operation
Note: “u” stands for unchanged
The following table indicates the way in which the various components of the microcontroller are
affected after a power-on reset occurs.
Item
Program Counter
Interrupts
WDT
Timer/Event Counter
Prescaler
Input/output Ports
Stack Pointer
Condition After RESET
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
I/O ports will be setup as inputs
Stack Pointer will point to the top of the stack
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.
Register
PCL
MP0
MP1
BP
ACC
TBLP
TBHP
TBLH
WDTS
STATUS
INTC0
INTC1
TMR0
TMR0C
Power On
Reset
0000 0000
xxxx xxxx
xxxx xxxx
-- 0- -000
xxxx xxxx
xxxx xxxx
xxxx xxxx
--xx xxxx
-- -- -111
-- 00 xxxx
-000 0000
0000 0000
xxxx xxxx
0000 1000
WDT Time-out
(Normal Operation)
0000 0000
xxxx xxxx
xxxx xxxx
-- 0- -000
uuuu uuuu
uuuu uuuu
uuuu uuuu
-- uu uuuu
-- -- -111
-- 1u uuuu
-000 0000
0000 0000
xxxx xxxx
0000 1000
RES or LVR
(Normal
Operation)
0000 0000
xxxx xxxx
xxxx xxxx
-- 0- -000
uuuu uuuu
uuuu uuuu
uuuu uuuu
--uu uuuu
-- -- -111
-- uu uuuu
-000 0000
0000 0000
xxxx xxxx
0000 1000
RES or LVR Reset WDT Time-out
(Idle/Sleep)
(Idle/Sleep)
0000 0000
xxxx xxxx
xxxx xxxx
-- 0- -000
uuuu uuuu
uuuu uuuu
uuuu uuuu
-- uu uuuu
-- -- -111
-- 01 uuuu
-000 0000
0000 0000
xxxx xxxx
0000 1000
0000 0000
uuuu uuuu
uuuu uuuu
-- u- -uuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
-- uu uuuu
-- -- -uuu
-- 11 uuuu
-uuu uuuu
uuuu uuuu
uuuu uuuu
uuuu uuuu
Rev. 1.10
41
February 13, 2012