CHAPTER 25 ROM CORRECTION
User’s Manual U16899EJ2V0UD
424
(2) Assemble in advance the initial setting routine as shown in Figure 25-6 to correct the program.
Figure 25-6. Initial Setting Routine
No
Yes
Initial setting
Load the contents of external nonvolatile memory
into internal expansion RAM
Correction address register setting
ROM correction operation enabled
Is ROM
correction used ?
Note
ROM correction
Main program
Note Whether the ROM correction is used or not should be judged by the port input level. For example, when the
P20 input level is high, the ROM correction is used, otherwise, it is not used.
(3) After reset, store the corrected address and program that have been previously stored in the external
nonvolatile memory with initial setting routine for ROM correction of the user to internal expansion RAM (see
Figure 25-6).
Set the start address of the instruction to be corrected to CORAD0 and CORAD1, and set bits 1 and 3
(COREN0, COREN1) of the correction control register (CORCN) to 1.
(4) Set the main program so that the program branches from the specified address of the internal expansion RAM
(F7FDH) to the internal expansion RAM address where the corrected program is stored using the entire space
branch instruction (BR !addr16).
(5) After the main program is started, the fetch address value and the values set in CORAD0 and CORAD1 are
always compared by the comparator in the ROM correction circuit. When these values match, the correction
branch request signal is generated. Simultaneously the corresponding correction status flag (CORST0 or
CORST1) is set to 1.
(6) Branch to the address F7FDH by the correction branch request signal.
(7) Branch to the internal expansion RAM address set in (4) by the entire-space branch instruction of the address
F7FDH.
(8) When one place is corrected, the correction program is executed. When two places are corrected, the
correction status flag is checked with the branch destination judgment program, and branches to the correction
program.
Содержание MuPD78F0132H
Страница 2: ...User s Manual U16899EJ2V0UD 2 MEMO ...