7906 datasheet(391/531 Pages) RENESAS

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FLASH MEMORY VERSION

7906 Group User’s Manual Rev.2.0

19-14

19.2 Flash memory CPU reprogramming mode

19.2.4 Software commands

Software commands are described below.

Software commands and data must be read from and written into even-numbered addresses in the user

ROM area, 16 bits at a time. At writing of a command code, the high-order 8 bits (D8 to D15) are ignored.

(1) Read array command

Writing command code “FF16” at the 1st bus cycle pushes the microcomputer into the read array mode.

When an address to be read is input at the next and the following bus cycles, the contents at the

specified address are output to the data bus (D0 to D15), 16 bits at a time.

The read array mode is maintained until another software command is written.

(2) Read status register command

Writing command code “7016” at the 1st bus cycle outputs the contents of the status register to the

data bus (D0 to D7) by a read at the 2nd bus cycle. (See Table 19.2.2.)

(3) Clear status register command

Writing command code “5016” at the 1st bus cycle clears two bits (SR.4 and SR.5) of the status register

to “0.” (See Table 19.2.2.)

(4) Programming

This command executes programming, one word

at a time. Write command code “4016” at the

1st bus cycle and then write data at the 2nd

bus cycle, 16 bits at a time. After writing of

one word has been completed, the automatic

programming (programming and verification of

data) operation is initiated. During the automatic

programming operation, be sure not to access

the flash memory or not to execute the next

command. The completion of the automatic

programming can be recognized by the RY/BY

status bit (bit 0 at address 9E16).

After the automatic programming operation has

been completed, the result of it can be

recognized by reading out the status register.

(Refer to section “19.2.5 Full status check.”)

Figure 19.2.3 shows the programming operation

flowchart.

Note that, for the areas having already been

programmed, be sure to program after an erase

(block erase) operation. If the programming

command is executed for the areas having

already been programmed, no programming error

will occur, but the contents of the areas become

undefined.

Fig. 19.2.3 Programming operation flowchart

Full status check

Start

Command code

“4016” is written.

Data is written to an

arbitrary write address.

Programming

operation is completed.

YES

••• See Figure 19.2.6.

RY/BY status bit = “1”?

(bit 0 at address 9E16)

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