PIC18F4550-IP Datasheet, PDF (312/438 Pages) Microchip Technology – 28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PIC18F2455/2550/4455/4550
FIGURE 25-7:
EXTERNAL BLOCK TABLE READ (EBTRx) DISALLOWED
Register Values
TBLPTR = 0008FFh
PC = 003FFEh
Program Memory
000000h
0007FFh
000800h
TBLRD*
001FFFh
002000h
003FFFh
004000h
Configuration Bit Settings
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
005FFFh
006000h
007FFFh
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
Results: All table reads from external blocks to Blockn are disabled whenever EBTRx = 0.
TABLAT register returns a value of ‘0’.
FIGURE 25-8:
EXTERNAL BLOCK TABLE READ (EBTRx) ALLOWED
Register Values
TBLPTR = 0008FFh
PC = 001FFEh
Program Memory
000000h
0007FFh
000800h
TBLRD*
001FFFh
002000h
003FFFh
004000h
005FFFh
006000h
007FFFh
Configuration Bit Settings
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
WRT2, EBTR2 = 11
WRT3, EBTR3 = 11
Results: Table reads permitted within Blockn, even when EBTRBx = 0.
TABLAT register returns the value of the data at the location TBLPTR.
DS39632E-page 310
© 2009 Microchip Technology Inc.