Status Register - Renesas M16C/60 Series Hardware Manual

Under development
This document is under development and its contents are subject to change.
M16C/6N5 Group
Data Protect Function
Each block in the flash memory has a nonvolatile lock bit. The lock bit is effective when the FMR02 bit =
0 (lock bit enabled). The lock bit allows each block to be individually protected (locked) against program-
ming and erasure. This helps to prevent data from inadvertently written to or erased from the flash
memory. The following shows the relationship between the lock bit and the block status.
• When the lock bit = 0, the block is locked (protected against programming and erasure).
• When the lock bit = 1, the block is not locked (can be programmed or erased).
The lock bit is set to "0" (locked) by executing the Lock Bit Program command, and is set to "1" (unlocked)
by erasing the block. The lock bit cannot be set to "1" by a command.
The lock bit status can be read using the Read Lock Bit Status command
The lock bit function is disabled by setting the FMR02 bit to "1", with all blocks placed in an unlocked state.
(The lock bit data itself does not change state.) Setting the FMR02 bit to "0" enables the lock bit function
(lock bit data retained).
If the Block Erase or Erase All Unlocked Block command is executed while the FMR02 bit = 1, the target
block or all blocks are erased irrespective of how the lock bit is set. The lock bit for each block is set to "1"
after completion of erasure.
For details about the commands, refer to "Software Commands."

Status Register

The status register indicates the operating status of the flash memory and whether an erase or program-
ming operation terminated normally or in error. The status of the status register can be known by reading
the FMR0 register's FMR00, FMR06, and FMR07 bits.
Table 1.22.5 shows the status register.
In EW0 mode, the status register can be read in the following cases:
(1) When a given even address in the user ROM area is read after writing the Read Status Register
command
(2) When a given even address in the user ROM area is read after executing the Program, Block Erase,
Erase All Unlocked Block, or Lock Bit Program command but before executing the Read Array
command.
Sequencer Status (SR7 and FMR00 Bits)
The sequence status indicates the operating status of the flash memory. SR7 = 0 (busy) during auto
programming, auto erase, and lock bit write, and is set to "1" (ready) at the same time the operation
finishes.
Erase Status (SR5 and FMR07 Bits)
Refer to "Full Status Check".
Program Status (SR4 and FMR06 Bits)
Refer to "Full Status Check".
Rev.1.00 2003.05.30 page 275
Flash Memory