Toshiba TLCS-870/C1 Series, Manual

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21. Flash Memory
21.4 Toggle Bit (D6)
TMP89FM42
RA003
21.3.4 Product ID entry
This command activates the product ID mode. If an instruction to read the flash memory is executed in Prod-
uct ID mode, the vendor ID, flash ID and security status can be read from the flash memory.
21.3.5 Product ID exit
This command is used to exit the Product ID mode.
21.3.6 Security program
If the security program is enabled, the flash memory is write and read protected in parallel PROM mode, and
the flash memory overwrite command and the RAM loader command cannot be executed in serial PROM
mode.
To disable the security program, the chip erase must be performed. To check whether the security program is
enabled or disabled, read 0xFF7F in product ID mode. Refer to Table 21-4 for further details. The time needed
to enable or disable the security program is 40
µ
s maximum. The next command sequence cannot be executed
until the security program setting is completed. To check the completion of the security program setting, per-
form read operations twice on the same address in the flash memory, and perform polling until the same data is
read. When the security program setting is being made, bit 6 is reversed each time a read is performed.
21.4 Toggle Bit (D6)
After the flash memory write, the chip erase, and the security program command sequence are executed, the value
of the 6th bit (D6) in data read by a read operation is reversed each time a read is performed. This bit reversal can be
used as a software mechanism for checking the completion of each operation. Normally, perform read operations
twice on the same address in the flash memory, and perform polling until the same data is read from the flash mem-
ory.
After the flash memory write, the chip erase, and the security program command sequence are executed, the toggle
bit read by the first read operation is always "1".
Note 1: If FLSCR1<FLSMD> is set to "disable", the toggle bit is not reversed.
Note 2: Do not read the toggle bit by using a 16-bit transfer instruction. If the toggle bit is read using a 16-bit transfer
instruction, the toggle bit does not function properly.
Note 3: Because the instruction cycle is longer than the write time in SLOW mode, the value is not reversed, even if the
toggle bit is read right after the Byte Program is performed.
Table 21-4 Values to Be Read in Product ID Mode
Address Meaning Read value
0xF000 Vendor ID 0x98
0xF001 Flash ID 0x4D
0xFF7F Security status
0xFF: Security program disabled
Other than 0xFF: Security program enabled