You can manipulate the register values directly from BASIC.
They are also reserved words. The internal registers are :
BIT addressable registers
TCON |
Timer/counter control |
P1 |
Port 0 latch |
SCON |
Serial port control |
IE |
Interrupt enable |
P3 |
Port 3 latch |
IP |
Interrupt priority control |
PSW |
Program status word |
ACC |
Accumulator |
B |
B register |
BYTE addressable register
SP |
Stack pointer |
DPL |
Data pointer low word |
DPH |
Data pointer high word |
PCON |
Power control |
TMOD |
Timer/counter mode control |
TL0 |
Timer/counter 0 low byte |
TL1 |
Timer/counter 1 low byte |
TH0 |
Timer/counter 0 high byte |
TH1 |
Timer/counter 1 high byte |
SBUF |
Serial data port |
P1 |
Port 1 latch |
P3 |
Port 3 latch |
The registers and their addresses are defined in the REG51.DAT file which
is placed in the BASCOM application directory.
You can use an other file for other uPs.
You can select the appropriate register file with the Options Compiler settings.
Take care when you are directly manipulating registers!
The ACC and B register are frequently used by BASCOM.
Also the SP register is better to be left alone.
Altering SP will certainly crash your application!
Bit addressable registers can be used with the SET/RESET statements and as bit-variables.
Byte addressable registers can be used as byte variables.
P1 = 40 will place a value of 40 into port 40.
Please note that internal registers are reserved words.
This means that they can't be dimensioned as BASCOM variables!
So you can't use the statement DIM B as Byte because B is an internal register.
You can however manipulate the register with the B = value statement.
Making your own register file is very simple:
| • | copy the 8052.DAT file to a new DAT file for example myproc.DAT |
DOS c:\bascom copy 8052.dat myproc.dat
| • | edit the registerfile with BASCOM |
A register file has a few sections. The following example shows only a few items under each section.
The [BIT] section contains all SFR's which are bit addressable. A bit addressable SFR ends with 0 or 8.
After the SFR name you can write the hexadecimal address.
An optional initial value for the simulator can also be specified. Separate the values by a comma.
Acc = E0 , 00
The [BYTE] section contains all the other SFR's.
The [MISC] section has a few items:
| • | up : here you can enter a short name for the uP. |
| • | IRAM : the amount of available internal memory (128 or 256 bytes) |
| • | org : the hexadecimal address where the code can start. This is 3 bytes after the last interrupt entry address, because the last interrupt will have a LJMP to an ISR and a LJMP needs 3 bytes. |
| • | I_xxx : where xxx is the name of the additional interrupt. The name must be no longer than 6 characters. As you can see in the example below the last interrupt T2 has an entry address of 73 (hex). So the org is set to 73+3 = 76 (hex). |
You only need to specify the additional interrupts. The interrupts for INT0,INT1, TIMER0, TIMER1 and SERIAL are already handled by the compiler.
| • | CLOCKDIV : The division factor of the oscillator. By default this is 12 and when you don't specify it, 12 will be used. Some micro processors have a division factor of 6 or 4. |
EXAMPLE
[BIT]
ACC = E0
B = F0
[BYTE]
ADCH = C6
ADCON = C5
CTCON = EB
[MISC]
up = 80552
I_TIMER2 = 2B
I_CT0 = 33
I_CT1 = 3B
I_CT2 = 43
I_CT3 = 4B
I_ADC = 53
I_CM0 = 5B
I_CM1 = 63
I_CM2 = 6B
I_T2 = 73
org = 76
IRAM = 256
CLOCKDIV = 12