STM8S datasheet(47/467 Pages) STMICROELECTRONICS

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Flash program memory and data EEPROM

However, the programming time can be fixed by setting the FIX bit of the FLASH_CR1

(see Section 4.8.1: Flash control register 1 (FLASH_CR1)). The programming time is

consequently fixed and equal to the sum of the erase and write time (see tPROG in Table

“Flash program memory” in the datasheet).

Note:

To write a byte fast (no erase), the whole word (4 bytes) into which it is written must be

erased beforehand. Consequently, It is not possible to do two fast writes to the same word

(without an erase before the second write): The first write will be fast but the second write to

the other byte will require an erase.

4.6.3

Word programming

A word write operation allows an entire 4-byte word to be programmed in one shot, thus

minimizing the programming time.

As for byte programming, word operation is available both for the main program memory

and data EEPROM. On some devices, the read-while-write (RWW) capability is also

available when a word programming operation is performed on the data EEPROM. Refer to

the datasheets for additional information.

•

In the main program memory:

The application stops for the duration of the byte program operation.

•

In DATA area

–

Devices with RWW capability: Program execution does not stop, and the byte

program operation is performed using the read-while-write (RWW) capability in

IAP mode.

–

Devices without RWW capability: The application stops for the duration of the byte

program operation.

To program a word, the WPRG/NWPRG bits in the FLASH_CR2 and FLASH_NCR2

registers must be previously set/cleared to enable word programming mode (see

Section 4.8.2: Flash control register 2 (FLASH_CR2) and Section 4.8.2: Flash control

starting with the first address. The programming cycle starts automatically when the 4 bytes

have been written.

As for byte operation, the EOP and the WR_PG_DIS control flags of FLASH_IAPSR,

together with the Flash interrupt, can be used to determine if the operation has been

correctly completed.

4.6.4

Block programming

Block program operations are much faster than byte or word program operations. In a block

program operation, a whole block is programmed or erased in a single programming cycle.

Refer to Table 5 for details on the block size according to the devices.

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