TMP92FD54AI datasheet(25/84 Pages) TOSHIBA

25 / 84 page

2006-01-27

92FD54AI-25

TMP92FD54AI

4.3.2

Single-Boot Mode

This mode involves activation of the internal boot ROM (mask ROM) so that the flash

memory can be rewritten using a program stored in the boot ROM. In this mode the

internal boot ROM is mapped into an area containing the interrupt vector table, in

which the boot ROM program is executed. The flash memory is mapped into an address

space different from the one into which the boot ROM is mapped (see

Figure 4.2.2).

In Single-Boot Mode the flash memory is rewritten by serial transfer of commands and

data.

First, the device’s SIO (SIO1) and the external host are connected and the rewrite

program is copied from the external host into the device’s internal RAM; the rewrite

program is then executed in RAM and the flash memory rewritten. The rewrite routine

is initiated by sending commands and rewrite data from the host. The device must

communicate with the host following the protocol described later. Before the program

can be transferred into RAM, the user password is checked to ensure the security of the

user ROM data. If the password does not match, the program is not transferred into

RAM. Interrupts must be disabled when peripheral functions such as the SIO is

utilized in Single Boot mode. Nonetheless, the code for an interrupt cause is recorded

in the INTES1 register ; thus, for example, data receptions or transmissions in the SIO

can be confirmed by keeping track of value changes of the INTES1 register. The NMI

interrupt must be disabled at this time.

To prevent the contents of flash memory inadvertently rewritten in Single-Chip Mode

(Normal Mode), it is recommended that, on completion of rewriting, write-protect be

set for any blocks which the user wishes to protect. For details of how to program/erase

the flash memory, please refer to Section 4.4, Programming/Erasing Flash Memory

during On-Board Programming.

TMP92FD54AI データシート(PDF) 25 Page - Toshiba Semiconductor