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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
RAM Data Memory
Special Function Registers
To ensure successful operation of the microcontroller, certain internal registers, known as Special
Function Registers or SFRs for short, are implemented in the Data Memory area. These registers
ensure correct operation of internal functions such as timers, interrupts, etc., as well as external
functions such as I/O data control. The SFRs are located at the address range 80H to FFH in
the upper section and are addressed directly. All can be addressed by byte but some are also
bit-addressable. The following table shows the SFR register list. Note that some of the registers are
defined by standard 8051 protocol while others are defined by Holtek.
Special Function Register Map
High 5-bit
Address
Low 3-bit Address
0H
1H
2H
3H
4H
5H
6H
7H
F8h
FMCR
FMKEY
FMAR0
FMAR1
FMAR�
FMDR
T�CON1
RSTSRC
F0h
B
ADCR0
ADCR1
ADCR�
ADPGA
ADRL
ADRH
SRST
E8h
SPCON
I�CLK
LVRCR
LVDCR
SCCR
PLLCR
LSOCR
HSOCR
E0h
ACC
SPSTA
FMSR
SPDAT
IP1
IP1H
IP�
IP�H
D8h
I�CCON
P�
I�CDAT
I�CADR
SBRCON
I�CSTA
CP0CR
CP1CR
D0h
PSW
—
—
—
—
—
—
—
C8h
T�CON
IEN3
CRCL
CRCH
TL�
TH�
IP3
IP3H
C0h
IRCON
CCEN
CCL1
CCH1
CCL�
CCH�
CCL3
CCH3
B8h
IP0
IP0H
S0RELH
S1RELH
—
CPHCR
CPICR
IRCON�
B0h
P3
P4
TBCR
DACTRL
DAL
DAH
P3M0
P3M1
A8h
IEN0
IEN1
S0RELL
—
—
—
P�M0
P�M1
A0h
P�
T3CON
TL3
TH3
SRCR
SPPRE
P1M0
P1M1
98h
S0CON
S0BUF
IEN�
S1CON
S1BUF
S1RELL
P0M0
P0M1
90h
P1
P0WAKE
DPS
DPC
—
—
WDTCR
—
88h
TCON
TMOD
TL0
TL1
TH0
TH1
—
TMPRE
80h
P0
SP
DPL
DPH
DPL1
DPH1
WDTREL
PCON
Notes:
“—“: �nimplemented
Most of the Special Function Registers will be described in detail under the function that they
are related to. In this section a register description is provided for those registers which are not
described elsewhere.