tmp89fm42 TOSHIBA Semiconductor CORPORATION, tmp89fm42 Datasheet - Page 329

• Manufacturer Part Number: tmp89fm42
• Description: 8 Bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

RA003
21.5 Access to the Flash Memory Area
21.5.1 Flash memory control in serial PROM mode
the flash memory, if data in flash memory is being erased or if a security setting is being made in the flash memory.
When performing these operation on the flash memory area, the flash memory cannot be directly accessed by using
a program in the flash memory; the flash memory must be accessed using a program in the BOOTROM area or the
RAM area.
erased in units of 4 kbytes, and all data in the flash memory can be erased at one stroke. A read can be performed
using one memory transfer instruction. A write or erase, however, must be performed using more than one memory
transfer instruction because the command sequence method is used. For information on the command sequence,
refer to Table 21-1.
21.5.1.1 How to transfer and write a control program to the RAM area in RAM loader mode of
A read or a program fetch cannot be performed on the whole of the flash memory area if data is being written to
Data can be written to and read from the flash memory area in units of one byte. Data in the flash memory can be
Note 1: To allow a program to resume control on the flash memory area that is rewritten, it is recommended that you let
Note 2: Do not reset the MCU (including a reset generated due to internal factors) when data is being written to the flash
BOOTROM area. Since almost all operations relating to access to the flash memory can be controlled simply
using data supplied through the serial interface (UART or SIO), it is not necessary to operate the control regis-
ter for the user. For details of the serial PROM mode, see "Serial PROM Mode".
other than UART and SIO, it is necessary to execute a control program in the RAM area by using the RAM
loader command of the serial PROM mode. How to execute this control program is described in "21.5.1.1 How
to transfer and write a control program to the RAM area in RAM loader mode of the serial PROM mode".
The serial PROM mode is used to access the flash memory by using a control program provided in the
To access the flash memory in serial PROM mode by using a user-specific program or peripheral functions
the program jump (return) after verifying that the program has been written properly.
memory, data is being erased from the flash memory or the security command is being executed. If a reset
occurs, there is the possibility that data in the flash memory may be rewritten to an unexpected value.
the serial PROM mode
program to be executed in the RAM area must be generated in the Intel-Hex format and be transferred
using the RAM loader of the serial PROM mode.
trolled by a program transferred to the RAM area. The following procedure is linked with a program
example to be explained later.
How to execute a control program in the RAM area in serial PROM mode is described below. A control
Steps 1 and 2 shown below are controlled by a program in the BOOTROM, and other steps are con-
1. Transfer the write control program to the RAM area in RAM loader mode.
2. Jump to the RAM area.
3. Set a nonmaskable interrupt vector in the RAM area.
4. Set FLSCR1<FLSMD> to "0y101", and specify the area to be erased by making the appropriate
5. Execute the erase command sequence.
6. Read the same flash memory address twice consecutively.
7. Specify the area (area erased in step 5 above) to which data is written by making the appropriate
8. Execute the write command sequence.
9. Read the same flash memory address twice consecutively.
FLSCR1<FAREA> setting. (Make the appropriate FLSCR1<ROMSEL> setting as required.)
Then set "0xD5" on FLSCR2<CR1EN>.
(Repeat step 6 until the read values become the same.)
FLSCR1<FAREA> setting. (Make the appropriate FLSCR1<ROMSEL> setting as required.)
Then set "0xD5" on FLSCR2<CR1EN>.
(Repeat step 9 until the read values become the same.)
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