MITSUBISHI MICROCOMPUTERS
M37905F8CFP, M37905F8CSP
16-BIT CMOS MICROCOMPUTER
Software Commands
Table 2 lists the software commands.
Start
By writing a software command after the CPU reprogramming mode
select bit has been set to “1”, erasing, programming, etc. can be
specified. Note that, at software commands’ input, the high-order
byte (D8–D15) is ignored. (Except for the write data at the 2nd cycle
of a programming command.)
Single-chip mode,
Memory expansion mode,
or Boot mode
Software commands are explained as below.
Read Array Command (FF16)
The processor mode register 1 is set (Note 1).
Flag I is set to “1”.
By writing command code “FF16” at the 1st bus cycle, the microcom-
puter enters the read array mode. If an address to be read is input in
the next or the following bus cycles, the contents at the specified ad-
dress are output to the data bus (D0 to D15) in a unit of 16 bits.
The read array mode is maintained until writing of another software
command.
The user-original reprogramming control software
for the CPU reprogramming mode is transferred to
the internal RAM.
Jump to the above software in the internal RAM.
(The operations shown below will be executed by
the above software in this RAM.)
Read Status Register Command (7016)
Writing command code “7016” at the 1st bus cycle outputs the con-
tents of the status register to the data bus (D0-D7) by a read at the
2nd bus cycle.
(Only in the boot mode.)
The user ROM area select bit is set to “1”.
The status register is explained later.
Clear Status Register Command (5016)
This command clears two status bits (SR.4, 5) each of which is set
to “1” to indicate that the operation has been terminated by an error.
To clear these bits, write command code “5016” at the 1st bus cycle.
Writing of “1” to the CPU reprogramming mode select bit.
(Writing of “0” → Writing of “1”)
Programming Command (4016)
Operations such as erasing, programming are
executed by using software commands.
This command facilitates programming of 1 word (2 bytes) at a time.
To initiate programming, write command code “4016” at the 1st bus
cycle; when write data is written in a unit of 16 bits at the 2nd bus
cycle, the address is specified at the same time. Upon completion of
data writing, automatic programming (data programming and verifi-
cation) operation is started.
Read array command is executed, or reset is
performed by setting the flash memory reset bit.
(Writing of “1” → Writing of “0”) (Note 2)
The completion of the automatic programming operation is con-
firmed by a read of the flash memory control register. The RY/BY sta-
tus bit of the flash memory control register goes “0” during the
automatic programming operation; and also, it goes “1” after the
end of it.
Writing of “0” to the CPU reprogramming mode
select bit.
(Only in the boot mode.)
Writing of “0” to user ROM area select bit (Note 3).
Before execution of the next command, be sure to confirm that the
RY/BY status bit is set to “1” (READY). During the automatic pro-
gramming operation, writing of commands and access to the flash
memory must not be performed.
Completed
When programming continuously, the programming command can
be executed with the read status register mode kept if there is no
programming error. Simultaneously with start of the automatic pro-
gramming, the read status register mode is automatically active. In
this case, the read status register mode is retained until the next read
array command (FF16) is written or until the reset is performed by
using the flash memory reset bit.
Notes 1: The processor mode register 1’s bit 7 (address 5F16, the
internal ROM bus cycle select bit) must be “0” (bus cycle
= 3φ).
2: To terminate the CPU reprogramming mode after the
erase and programming operations have been
completed, be sure to execute the read array command
or perform the flash memory reset operation.
3: This bit may remain “1”. However, if this bit is “1”, the
user ROM area access is specified.
Reading out the status register after the automatic programming op-
eration is completed reports the result of it. For details, refer to the
section on the status register.
Figure 9 shows an example of the programming flowchart.
Additional programming to any word that has already been pro-
grammed is prohibited.
Fig. 8 CPU reprogramming mode set/termination flowchart
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