HT45R38
Program Memory
-
ROM
The program memory is used to store the program in-
structions which are to be executed. It also contains
data, table, and interrupt entries, and is organized into
4096´15 bits, addressed by the program counter and ta-
ble pointer.
Certain locations in the program memory are reserved
for special usage:
·
Location 000H
·
Location 00CH
This location is reserved for the Timer/Event Counter
0 interrupt service program. If a Timer 0 interrupt re-
sults from a Timer/Event Counter 0 overflow, and the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at this location.
·
Location 010H
This area is reserved for program initialisation. After a
device reset, the program always begins execution at
location 000H.
·
Location 004H
This location is reserved for the external RC oscilla-
tion converter interrupt service program. If an external
RC oscillation converter interrupt results from an ex-
ternal RC oscillation converter interrupt is activated,
and the interrupt is enabled and the stack is not full,
the program begins execution at this location.
·
Location 014H
This location is reserved for the external interrupt 0
service program. If the INT0 input pin is activated, the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at this location.
·
Location 008H
This location is reserved for the Timer/Event Counter
1 interrupt service program. If a Timer 1 interrupt re-
sults from a Timer/Event Counter 1 overflow, and the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at this location.
·
Location 018H
This location is reserved for the external interrupt 1
service program. If the INT1 input pin is activated, the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at this location.
0 0 0 H
0 0 4 H
0 0 8 H
0 0 C H
D e v ic e In itia liz a tio n P r o g r a m
E x te rn a l In te rru p t 0
E x te rn a l In te rru p t 1
T im e r /E v e n t C o u n te r 0 O v e r flo w
This location is reserved for the A/D converter inter-
rupt service program. If an A/D converter interrupt re-
sults from an end of A/D conversion, and if the
interrupt is enabled and the stack is not full, the pro-
gram begins execution at this location.
·
Table location
0 1 0 H
E x te r n a l R C O s c illa tio n C o n v e r te r In te r r u p t
0 1 4 H
0 1 8 H
T im e r /E v e n t C o u n te r 1 O v e r flo w
A /D
C o n v e rte r In te rru p t
P ro g ra m
M e m o ry
n 0 0 H
n F F H
F 0 0 H
F F F H
L o o k - u p T a b le ( 2 5 6 w o r d s )
L o o k - u p T a b le ( 2 5 6 w o r d s )
1 5 - B its
N o te : n ra n g e s fro m 0 to F
Program Memory
Any location in the program memory can be used as a
look-up table. The instructions
²TABRDC
[m]² (the
current page, 1 page=256 words) and
²TABRDL
[m]²
transfer the contents of the lower-order byte to the
specified data memory, and the higher-order byte to
TBLH (08H). Only the destination of the lower-order
byte in the table is well-defined, the other bits of the ta-
ble word are transferred to the lower portion of TBLH,
and the remaining 1 bit is read as
²0².
The table
higher-order byte register (TBLH) is read only. The ta-
ble pointer (TBLP) is a read/write register (07H),
which indicates the table location. Before accessing
the table, the location must be placed in TBLP. The
TBLH is read only and cannot be restored. If the main
routine and the ISR (Interrupt Service Routine) both
employ the table read instruction, the contents of the
TBLH in the main routine are likely to be changed by
the table read instruction used in the ISR. Errors may
Table Location
Instruction
TABRDC [m]
TABRDL [m]
*11
P11
1
*10
P10
1
*9
P9
1
*8
P8
1
*7
@7
@7
*6
@6
@6
*5
@5
@5
*4
@4
@4
*3
@3
@3
*2
@2
@2
*1
@1
@1
*0
@0
@0
Table Location
Note: *11~*0: Table location bits
@7~@0: Table pointer bits
Rev. 1.00
8
December 13, 2006
P11~P8: Current program counter bits
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
