PIC18F2420/2520/4420/4520
FIGURE 23-7:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Program Memory Configuration Bit Settings
Register Values
000000h
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
0007FFh
000800h
TBLPTR = 0008FFh
001FFFh
002000h
TBLRD*
PC = 003FFEh
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
003FFFh
004000h
005FFFh
006000h
WRT3, EBTR3 = 11
007FFFh
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
FIGURE 23-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
WRTB, EBTRB = 11
0007FFh
000800h
TBLPTR = 0008FFh
PC = 001FFEh
WRT0, EBTR0 = 10
TBLRD*
001FFFh
002000h
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
003FFFh
004000h
005FFFh
006000h
007FFFh
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
© 2008 Microchip Technology Inc.
DS39631E-page 265
MICROCHIP [ MICROCHIP ]
