TMP92FD54AI datasheet(17/84 Pages) TOSHIBA

17 / 84 page

2006-01-27

92FD54AI-17

TMP92FD54AI

User Boot Mode

(1-A) Example procedure in which the rewrite routine is stored in the internal flash memory

(Step 1)

First, the conditions (e.g. the pin status) under which the program will enter User Boot Mode must be

set and the I/O bus which the program will use to transfer data must be selected. Then a circuit must be

designed and a corresponding program written. Before mounting this device on the board, the following

four programs must be written into one of the blocks of the flash memory using a programmer or similar

device.

(a) Mode judgment routine:

code to determine when rewriting of the device will commence

(b) Flash rewrite routine:

code to read the rewrite data from an external source and then

rewrite the flash memory

code to copy (a) to (d) into the internal RAM or to external

memory

(d) Copy routine-2:

code to copy (a) to (d) to the flash memory from the internal RAM

or the external memory.

(Step 2)

The following explanation of the proceeding step assumes that the routines described above have

been included in the Reset-processing program.

After a Reset the Reset-processing program must first determine whether or not the device should

enter User Boot Mode. If the condition for entering User Boot Mode is true, the program must put the

device into User Boot Mode, the mode in which the flash memory can be rewritten. (Once the device

has entered User Boot Mode, no interrupts ⎯ not even NMIs ⎯ should be used.)

(TMP92FD54AI)

Flash memory

RAM

[Reset-processing program]

Old user application

program

(Controller)

New user

application program

(I/O)

(a) Mode judgment routine

(b) Flash rewrite routine

(d) Copy routine-2

(TMP92FD54AI)

Flash memory

RAM

[Reset-processing program]

Old user application

program

(Controller)

New user

application program

(I/O)

→ 1 RESET

Condition for

determining

whether or not the

device should be

put into User Boot

Mode (set by the

user)

(a) Mode judgment routine

(b) Flash rewrite routine

(d) Copy routine-2

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