HT85F2270 datasheet(3/226 Pages) HOLTEK

3 / 226 page

Rev. 1.00

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Standard 8051 8-Bit Flash MCU

HT85F2260/HT85F2270/HT85F2280

Program �emor� Protection ............................................................................................. 4�

�emor� Protection Control B�tes................................................................................................. 4�

19 RAM Data Memory.............................................................................................. 46

Structure............................................................................................................................ 46

Register Banks.................................................................................................................. �0

Bit Addressable Space ...................................................................................................... �0

Special Function Registers................................................................................................ ��

ACC Register – Accumulator........................................................................................................ ��

B Register .................................................................................................................................... ��

SP Register – Stack Pointer......................................................................................................... ��

DPL� DPH� DPL1� DPH1 Registers – Data Pointer Registers...................................................... ��

Data Pointer Select Registers ...................................................................................................... �4

Data Pointer Control Register....................................................................................................... �4

Program Status Word................................................................................................................... �6

20 Oscillators ........................................................................................................... 57

S�stem Oscillator Overview .............................................................................................. �7

System Clock Configuration.............................................................................................. �7

External High Speed Cr�stal Oscillator – HXT ............................................................................. �7

Internal High Speed RC Oscillator – HIRC................................................................................... �8

External Low Speed Cr�stal Oscillator – LXT............................................................................... �8

Internal Low Speed RC Oscillator – LIRC .................................................................................... �9

21 Operating Modes and System Clocks .............................................................. 60

S�stem Clocks Description................................................................................................ 60

Phase Locked Loop – PLL ................................................................................................ 64

Changing the PLL Frequenc�....................................................................................................... 64

Operation �odes............................................................................................................... 66

NOR�AL �ode ............................................................................................................................ 66

IDLE �ode.................................................................................................................................... 66

Power-Down �ode....................................................................................................................... 66

Power Control Register ..................................................................................................... 67

Standb� Current Considerations ....................................................................................... 67

Wake-up ............................................................................................................................ 68

22 Watchdog Timer.................................................................................................. 69

Watchdog Registers .......................................................................................................... 70

Watchdog Timer Clock Source.......................................................................................... 7�

Watchdog Timer Operation ............................................................................................... 7�

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