Datasheet

4
4235K–8051–05/08
AT89C51RD2/ED2
3. SFR Mapping
The Special Function Registers (SFRs) of the AT89C51RD2/ED2 fall into the following
categories:
• C51 core registers: ACC, B, DPH, DPL, PSW, SP
• I/O port registers: P0, P1, P2, P3, PI2
• Timer registers: T2CON, T2MOD, TCON, TH0, TH1, TH2, TMOD, TL0, TL1, TL2, RCAP2L,
RCAP2H
• Serial I/O port registers: SADDR, SADEN, SBUF, SCON
• PCA (Programmable Counter Array) registers: CCON, CCAPMx, CL, CH, CCAPxH, CCAPxL
(x: 0 to 4)
• Power and clock control registers: PCON
• Hardware Watchdog Timer registers: WDTRST, WDTPRG
• Interrupt system registers: IE0, IPL0, IPH0, IE1, IPL1, IPH1
• Keyboard Interface registers: KBE, KBF, KBLS
• SPI registers: SPCON, SPSTR, SPDAT
• BRG (Baud Rate Generator) registers: BRL, BDRCON
• Clock Prescaler register: CKRL
• Others: AUXR, AUXR1, CKCON0, CKCON1
Table 3-1. C51 Core SFRs
Mnemonic Add Name 7 6 5 4 3 2 1 0
ACC E0h Accumulator
B F0h B Register
PSW D0h Program Status Word CY AC F0 RS1 RS0 OV F1 P
SP 81h Stack Pointer
DPL 82h Data Pointer Low Byte
DPH 83h Data Pointer High Byte
Table 3-2. System Management SFRs
Mnemonic Add Name 7 6 5 4 3 2 1 0
PCON 87h Power Control SMOD1 SMOD0 - POF GF1 GF0 PD IDL
AUXR 8Eh Auxiliary Register 0 DPU - M0 XRS2 XRS1 XRS0 EXTRAM AO
AUXR1 A2h Auxiliary Register 1 - - ENBOOT - GF3 0 - DPS
CKRL 97h Clock Reload Register - - - - - - - -
CKCKON0 8Fh Clock Control Register 0 - WDTX2 PCAX2 SIX2 T2X2 T1X2 T0X2 X2
CKCKON1 AFh Clock Control Register 1 - - - - - - - SPIX2