
CPU Rewrite Mode
191
Specifications in this manual are tentative and subject to change
Rev. E
MITSUBISHI MICROCOMPUTERS
M30245 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Figure 1.143. Page program flowchart
n = FE16
Start
Write 4116
n = 0
Write address n and
data n
RY/BY status flag
= 1?
Check full status
Page program
completed
n = n + 2
NO
YES
NO
YES
1. Read Array Command (FF16)
The read array mode is entered by writing the command code “FF16” in the first bus cycle.
When an even address that is to be read is input in one of the bus cycles that follow, the
content of the specified address is read out at the data bus (D0–D15), 16 bits at a time.
The read array mode is retained until another command is written.
2. Read Status Register Command (7016)
When the command code “7016” is written in the first bus cycle, the content of the status
register is read out at the data bus (D0–D7) by a read in the second bus cycle.
3. Clear Status Register Command (5016)
This command clears the bits SR3 to SR5 of the status register after being set. These bits
indicate that operation has ended in an error. To use this command, write the command
code “5016” in the first bus cycle.
4. Page Program Command (4116)
Page program allows for high-speed programming in units of 256 bytes. Page program
operation starts when the command code “4116” is written in the first bus cycle. In the
second bus cycle through the 129th bus cycle, the write data is sequentially written 16 bits at
a time. At this time, the addresses A0-A7 need to be incremented by 2 from “0016” to “FE16.”
When the system finishes loading the data, it starts an auto write operation (data program
and verify operation). Figure 1.143 shows an example of a page program flowchart.
The completed auto write operation can be confirmed by reading the status register or the
flash memory control register 0. At the same time the auto write operation starts, the read
status register mode is automatically entered, so the content of the status register can be
read out. The status register bit 7 (SR7) is set to 0 at the same time the auto write operation
starts and is returned to 1 when the auto write operation has been completed. In this case,
the read status register mode remains active until the Read Array command (FF16) or Read
Lock Bit Status command (7116) is written or the flash memory is reset using its reset bit.
The RY/BY status flag of the flash memory control register 0 is “0” during auto write opera-
tion and “1” when the auto write operation and status register bit 7 have been completed.
After the auto write operation is completed, the status register can read out the results of the
auto write operation. Refer to the status register section for more details.
Each block of the flash memory can be write protected by using a lock bit. Refer to the data
protect function section for more details. Additional writes to the pages previously pro-
grammed are prohibited.