PIC18F2450/4450
FIGURE 18-7:
EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
000FFFh
WRTB, EBTRB = 11
001000h
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
TBLPTR = 0008FFh
PC = 003FFEh
001FFFh
002000h
TBLRD*
003FFFh
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
FIGURE 18-8:
EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
Register Values
Program Memory
Configuration Bit Settings
000000h
0007FFh
000FFFh
WRTB, EBTRB = 11
001000h
TBLPTR = 0008FFh
PC = 001FFEh
WRT0, EBTR0 = 10
TBLRD*
001FFFh
002000h
WRT1, EBTR1 = 11
003FFFh
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
DS39760A-page 208
Advance Information
© 2006 Microchip Technology Inc.
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