PIC17C752-08/CL MICROCHIP [Microchip Technology], PIC17C752-08/CL Datasheet - Page 62

• Manufacturer Part Number: PIC17C752-08/CL
• Description: High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC17C7XX
8.3
The table read allows the program memory to be read.
This allows constants to be stored in the program
memory space, and retrieved into data memory when
needed.
gram memory address TBLPTR. After the dummy
byte has been read from the TABLATH, the TABLATH
is loaded with the 16-bit data from program memory
address TBLPTR, and then increments the TBLPTR
value. The first read loads the data into the latch, and
can be considered a dummy read (unknown data
loaded into 'f'). INDF0 should be configured for either
auto-increment or auto-decrement.
FIGURE 8-7:
FIGURE 8-8:
DS30289A-page 62
AD15:AD0
Instruction
fetched
Instruction
executed
Table Reads
Example 8-2
WR
ALE
OE
AD15:AD0
Instruction
fetched
Instruction
executed
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
'1'
TABLRD TIMING
TABLRD TIMING (CONSECUTIVE TABLRD INSTRUCTIONS)
INST (PC-1)
TABLRD1
ALE
PC
reads the 16-bit value at pro-
WR
OE
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
'1'
TABLRD1 cycle1 TABLRD1 cycle2 TABLRD2 cycle1 TABLRD2 cycle2
INST (PC-1)
TABLRD
TABLRD2
PC
PC+1
TABLRD cycle1
Data read cycle
INST (PC+1)
PC+1
TBL1 Data in 1
EXAMPLE 8-2:
MOVLW
MOVWF
MOVLW
MOVWF
TABLRD
TLRD
TABLRD
INST (PC+2)
Data read cycle
TABLRD cycle2
PC+2
TBL
HIGH (TBL_ADDR) ; Load the Table
TBLPTRH
LOW (TBL_ADDR)
TBLPTRL
0, 1, DUMMY
1, INDF0
0, 1, INDF0
Data in
Data read cycle
TABLE READ
TBL2 Data in 2
INST (PC+2)
INST (PC+1)
1998 Microchip Technology Inc.
PC+2
; Dummy read,
;
;
; Read HI byte
;
; Read LO byte
;
;
;
;
;
;
Updates TABLATH
Increments TBLPTR
of TABLATH
of TABLATL and
Update TABLATH
Increment TBLPTR
INST (PC+3)
address
INST (PC+2)
PC+3