Registers 8051 family

name	description		adress
---	-----------		------
ACC	acummulator		E0		
B	B register		F0		
DPTR	datapointer 				
DPH	datapointer highbyte	83		
DPL	datapointer lowbyte	82		
IE	interrupt enable	A8	
IP	interrupt priority	B8
P0	port 0			80
P1	port 1			90
P2	port 2			A0
P3	port 3			B0
PCON	power control		87
PSW	program status word	D0
SBUF	serial databuffer	99
SCON	serial controller	98
SP	stack pointer		81
TCON 	timer control		88
TH0	timer high 0		8C
TH1	timer high 1		8D
TL0	timer low  0		8A
TL1	timer low  1		8B
TMOD	timer mode		89


bit description symbol --- ----------- ------ B7 reserved B6 reserved B5 reserved B4 priority of serial port interrupt PS B3 priority of timer 1 interrupt PT1 B2 priority of external interrupt 1 PX1 B1 priority of timer 0 interrupt PT0 B0 priority of external interrupt 0 PX0


bit description symbol --- ----------- ------ B7 enable all interrupts EA B6 reserved B5 reserved B4 enable serial port interrupt ES B3 enable timer 1 interrupt ET1 B2 enable external interrupt 1 EX1 B1 enable timer 0 interrupt ET0 B0 enable external interrupt 0 EX0


bit description symbol --- ----------- ------ B7 carry flag CY B6 auxiliary carry flag AC B5 general purpose status flag F0 B4 register bank select bit 1 RS1 B3 register bank select bit 0 RS0 B2 overflow flag OV B1 user definable B0 parity of accumulator P


bit description symbol --- ----------- ------ B7 serial port mode SM0 B6 serial port mode SM1 B5 enable multiprocessorfeature in SM2 modes 2 & 3, RI will not be activated if RB8=0 & SM2=1 in mode 1 RI will not be activated if stop bit was invalid & SM2=1 SM2 should be 0 in mode 0 B4 enable reception REN B3 in modes 2&3 9-th bit tx TB8 B2 in modes 2&3 9-th bit rx RB8 mode1 ; if SM2=0 RB8=stop bit value mode0 ; not used B1 tx interrupt flag TI mode0 : set by 8-th bit time other modes : set by beginning of stop bit B0 rx interrupt flag RI Modes descr. Baudrate 00 shift register f_osc/1201 8-bit UART variable10 9-bit UART f_osc/64 of f_osc/3211 9-bit UART variable


bit description symbol --- ----------- ------ B7 timer 1 overflow flag TF1 B6 timer 1 on/off control TR1 B5 timer 0 overflow flag TF0 B4 timer 0 on/off control TR0 B3 interrupt 1 edge flag IE1 B2 interrupt 1 triggercontrol bit IT1 B1 interrupt 0 edge flag IE0 B0 interrupt 0 triggercontrol bit IT0


bit description symbol --- ----------- ------ B7 0 = t/c 1 enabled via TR1 GATE 1 = t/c enabled via INT1 + TR1 B6 timer = 0, counter = 1 T/C B5 operating modes t/c 1 M1 B4 operating modes t/c 1 M0 B3 idem for t/c 0B2 idem for t/c 0 B1 idem for t/c 0B0 idem for t/c 0 Modes 00 TLx serves as 5-bit prescaler 01 16-bit t/c THx & TLx are cascaded 10 8-bit reloader, valTHx is loaded in TLx when TLx overflows 11 TL0 is an 8-bit t/c controlled by Timer 0 controlbits TH0 is an 8-bit t/c controlled by Timer 1 controlbits t/c 1 stopped