Datasheet

Table Of Contents
PIC18F2221/2321/4221/4321 FAMILY
DS39689F-page 276 © 2009 Microchip Technology Inc.
FIGURE 24-7: EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED
FIGURE 24-8: EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
TBLRD*
TBLPTR = 0008FFh
PC = 007FFEh
Register Values Program Memory
(1)
Configuration Bit Settings
Boot Block
Block 0
Block 1
Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.
TABLAT register returns a value of ‘0’.
Note 1: See Figure 24-5 for block boundaries.
WRTB, EBTRB = 11
WRT0, EBTR0 = 10
WRT1, EBTR1 = 11
TBLRD*
TBLPTR = 0008FFh
PC = 003FFEh
Register Values Program Memory
(1)
Configuration Bit Settings
Boot Block
Block 0
Block 1
Results: Table reads permitted within Blockn, even when EBTRBn = 0.
TABLAT register returns the value of the data at the location TBLPTR.
Note 1: See Figure 24-5 for block boundaries.