PIC17C44 Datasheet, PDF (138/241 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM/ROM Microcontroller

PIC17C4X
TABLRD
Table Read
Example1:
TABLRD 1, 1, REG ;
Before Instruction
REG
TBLATH
TBLATL
TBLPTR
MEMORY(TBLPTR)
= 0x53
= 0xAA
= 0x55
= 0xA356
= 0x1234
After Instruction (table write completion)
REG
= 0xAA
TBLATH
= 0x12
TBLATL
= 0x34
TBLPTR
= 0xA357
MEMORY(TBLPTR) = 0x5678
Example2:
TABLRD 0, 0, REG ;
Before Instruction
REG
TBLATH
TBLATL
TBLPTR
MEMORY(TBLPTR)
= 0x53
= 0xAA
= 0x55
= 0xA356
= 0x1234
After Instruction (table write completion)
REG
= 0x55
TBLATH
= 0x12
TBLATL
= 0x34
TBLPTR
= 0xA356
MEMORY(TBLPTR) = 0x1234
TABLWT
Table Write
Syntax:
[ label ] TABLWT t,i,f
Operands:
0 ≤ f ≤ 255
i ∈ [0,1]
t ∈ [0,1]
Operation:
If t = 0,
f → TBLATL;
If t = 1,
f → TBLATH;
TBLAT → Prog Mem (TBLPTR);
If i = 1,
TBLPTR + 1 → TBLPTR
Status Affected: None
Encoding:
1010 11ti ffff ffff
Description:
1. Load value in ’f’ into 16-bit table
latch (TBLAT)
If t = 0: load into low byte;
If t = 1: load into high byte
2. The contents of TBLAT is written
to the program memory location
pointed to by TBLPTR
If TBLPTR points to external
program memory location, then
the instruction takes two-cycle
If TBLPTR points to an internal
EPROM location, then the
instruction is terminated when
an interrupt is received.
Note:
The MCLR/VPP pin must be at the programming
voltage for successful programming of internal
memory.
If MCLR/VPP = VDD
the programming sequence of internal memory
will be executed, but will not be successful
(although the internal memory location may be
disturbed)
3. The TBLPTR can be automati-
cally incremented
If i = 0; TBLPTR is not
incremented
If i = 1; TBLPTR is incremented
Words:
1
Cycles:
2 (many if write is to on-chip
EPROM program memory)
Q Cycle Activity:
Q1
Decode
Q2
Read
register 'f'
Q3
Execute
Q4
Write
register
TBLATH or
TBLATL
DS30412C-page 138
© 1996 Microchip Technology Inc.