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CHAPTER 21 ROM CORRECTION FUNCTION
■ If a Program Error Occurs
The original of a patch program and its address is transferred to the MCU via the connector (UART). The
MCU writes the information to E
■ Reset Sequence
After the reset sequence is completed, the MCU reads the value of E
patch program is not 0, the MCU reads the original patch program and writes it to RAM. Then, the MCU
sets the program address to PADR0 or PADR1 and enables the program to run. The first address of the
program written to RAM is saved in RAM as specified for each address detection register.
■ INT9 Interrupt
During execution of an interrupt routine, control checks the interrupt flag for an address in which an
interrupt was enabled, and branches to the corresponding program. The information stacked by the interrupt
is deleted. The interrupt flag is also cleared.
ROM
RAM
580
2
PROM.
Figure 21.5-2 System Configuration Example
FFFFFF
H
(3)
Abnormal program
(1)
Register setting
for ROM correction
Corrected program
(2)
000000
H
MB90460/465 series
2
PROM. If the number of bytes of the
2
External E
PROM
O Number of program byte
O Interrupt trigger address
O Corrected program
Data sent via UART
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