Registers 8052AH-BASIC

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
T2CON   timer 2 control         C8
TH0     timer high 0            8C
TH1     timer high 1            8D
TL0     timer low  0            8A
TL1     timer low  1            8B
TMOD    timer mode              89

IE

bit             description                             symbol
---             -----------                             ------
76543210
0-------        disable all interrupts                  EA
1-------        enable all interrupt control bits       EA
-x------        reserved
--0-----        timer 2 interrupt disabled              ET2
--1-----        timer 2 interrupt enabled               ET2
---0----        disable serial port interrupt           ES
---1----        enable serial port interrupt            ES
----0---        disable timer 1 interrupt               ET1
----1---        enable timer 1 interrupt                ET1
-----0--        disable external interrupt 1            EX1
-----1--        enable external interrupt 1             EX1
------0-        disable timer 0 interrupt               ET0
------1-        enable timer 0 interrupt                ET0
-------0        disable external interrupt 0            EX0
-------1        enable external interrupt 0             EX0

IP

bit             description                             symbol
---             -----------                             ------
76543210
x-------        reserved
-x------        reserved
--1-----        priority of timer 2                     PT2
---1----        priority of serial port interrupt       PS
----1---        priority of timer 1 interrupt           PT1
-----1--        priority of external interrupt 1        PX1
------1-        priority of timer 0 interrupt           PT0
-------1        priority of external interrupt 0        PX0

PSW

bit             description                             symbol
---             -----------                             ------
76543210
x-------        carry flag                              CY
-x------        auxiliary carry flag                    AC
--x-----        general purpose status flag             F0
---x----        register bank select bit 1              RS1
----x---        register bank select bit 0              RS0
-----x--        overflow flag                           OV
------x-        user definable
-------x        parity of accumulator                   P

SCON

bit             description                             symbol
---             -----------                             ------
76543210
x-------        serial port mode                        SM0
-x------        serial port mode                        SM1
00------        mode 0 : shift register         f_osc/1201
01------        mode 1 : 8-bit UART             variable10
10------        mode 2 : 9-bit UART             f_osc/64 of f_osc/3211
11------        mode 3 : 9-bit UART             variable
--x-----        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
---0----        disable reception                       REN
---1----        enable reception                        REN
----x---        in modes 2&3 9-th bit tx                TB8
-----x--        in modes 2&3 9-th bit rx                RB8
                mode1 ; if SM2=0 RB8=stop bit value
                mode0 ; not used
------x-        tx interrupt flag                       TI
                mode0 : set by 8-th bit time
                other modes : set by beginning of
                stop bit, clear by software .
-------x        rx interrupt flag                       RI
                hardware set at the end of 8th bit
                time in mode 0, halfway trough the
                stop bit time in other modes (see SM2)
                clear by software.

TCON

bit             description                             symbol
---             -----------                             ------
76543210
x-------        timer 1 overflow flag                   TF1
-0------        timer 1 off                             TR1
-1------        timer 1 on                              TR1
--0-----        timer 0 overflow flag                   TF0
                set on overflow, reset on jump
                to interrupt routine
---0----        timer 0 off                             TR0
---1----        timer 0 on                              TR0
----x---        interrupt 1 edge flag                   IE1
                set on external interrupt detect
                reset after interrupt processed
-----0--        interrupt 1 low level trigger           IT1
-----1--        interrupt 1 falling edge trigger        IT1
------x-        interrupt 0 edge flag (see IE1)         IE0
-------x        interrupt 0 triggercontrol (see IT1)    IT0

T2CON

bit             description                             symbol
---             -----------                             ------
76543210
x-------        timer 2 overflow flag                   TF2
-x------        timer 2 external flag                   EXF2
--x-----        receive clock flag                      RCLK
---x----        transmit clock flag                     TCLK
----x---        timer 2 external enable flag            EXEN2
-----0--        stop timer                              TR2
-----1--        start timer
------0-        internal timer                          C/T2
------1-        external timer
-------x        capture / reload flag                   CP/RL2

TMOD

bit             description                             symbol
---             -----------                             ------
76543210
0-------|       t/c enabled via TR1                     GATE
1-------|t      t/c enabled via  INT1 + TR1
-0------|i      timer                                   T/C
-1------|m      counter                                 T/C
--00----|e      TL1 serves as 5-bit prescaler           M1,M0
--01----|r      16-bit t/c TH1 & TL1 are cascaded
--10----|1      8-bit reloader, valTH1 is loaded in TL1 when TL1 overflows
--11----|       t/c 1 is stopped

0-------|       t/c enabled via TR0                     GATE
1-------|t      t/c enabled via  INT0 + TR0
-0------|i      timer                                   T/C
-1------|m      counter                                 T/C
--00----|e      TL0 serves as 5-bit prescaler           M1,M0
--01----|r      16-bit t/c TH0 & TL0 are cascaded
--10----|0      8-bit reloader, valTH0 is loaded in TL0 when TL0 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

950419

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mgeysken@innet.be