TMP86FS28DFG datasheet(227/272 Pages) TOSHIBA

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Page 215

TMP86FS28DFG

17.4 Access to the Flash Memory Area

When the write, erase and read protections are set in the flash memory, read and fetch operations cannot be per-

formed in the entire flash memory area. Therefore, to perform these operations in the entire flash memory area,

access to the flash memory area by the control program in the BOOTROM or RAM area. (The flash memory pro-

gram cannot write to the flash memory.) The serial PROM or MCU mode is used to run the control program in the

BOOTROM or RAM area.

Note 1: The flash memory can be written or read for each byte unit. Erase operations can be performed either in the entire

area or in units of 4 kbytes, whereas read operations can be performed by an one transfer instruction. However,

the command sequence method is adopted for write and erase operations, requiring several-byte transfer instruc-

tions for each operation.

Note 2: To rewrite data to Flash memory addresses at which data (including FFH) is already written, make sure to erase

the existing data by "sector erase" or "chip erase" before rewriting data.

17.4.1 Flash Memory Control in the Serial PROM Mode

The serial PROM mode is used to access to the flash memory by the control program provided in the

BOOTROM area. Since almost of all operations relating to access to the flash memory can be controlled sim-

ply by the communication data of the serial interface (UART), these functions are transparent to the user. For

the details of the serial PROM mode, see “Serial PROM Mode.”

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