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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Reset and Initialisation
Reset and Initialisation
ROM Code Check Reset
ID block addresses 0xF0~0xFF can be written into ROM codes such as the following table shows,
or a value of FFH which means no ROM codes are written into these addresses. When reading the
option table, the hardware will automatically compare with the ROM code pattern, if any one of the
ID block addresses has a mismatch, the MCU will automatically reset and re-read the option table
until all the ID block addresses are matched.
ID block address
ROM code
0xF0
01H/FFH
0xF1
�3H/FFH
0xF�
4�H/FFH
0xF3
67H/FFH
0xF4
89H/FFH
0xF�
ABH/FFH
0xF6
CDH/FFH
0xF7
EFH/FFH
0xF8
FEH/FFH
0xF9
DCH/FFH
0xFA
BAH/FFH
0xFB
98H/FFH
0xFC
76H/FFH
0xFD
�4H/FFH
0xFE
3�H/FFH
0xFF
10H/FFH
Reset Initial Conditions
The different types of reset described affect the reset flags in different ways. The following table
indicates the way in which the various components of the microcontroller are affected after a
power-on reset occurs.
Item
Condition After RESET
P�og�am Co�nte�
Reset to ze�o
Inte���pts
All inte���pts will be disabled
WDT
Clea� afte� �eset� WDT begins co�nting
Time�/Even Co�nte�s
Time�/Even Co�nte�s will be t��ned off
Inp�t/O�tp�t Po�ts
I/O po�ts will be set�p as a q�asi-bidi�ection st��ct��e
Stack Pointe�
Set to 007H val�e
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.