ST10F272 datasheet(29/179 Pages) STMICROELECTRONICS

29 / 179 page

ST10F272

Internal Flash memory

29/179

5.3

Write operation

The Flash module have one single register interface mapped in the memory space of the

IBUS (0x08 0000 to 0x08 0015). All the operations are enabled through four 16-bit control

registers: Flash Control Register 1-0 High/Low (FCR1H/L-FCR0H/L). Eight other 16-bit

registers are used to store Flash Address and Data for Program operations (FARH/L and

FDR1H/L-FDR0H/L) and Write Operation Error flags (FERH/L). All registers are accessible

with 8 and 16-bit instructions (since operates in 16-bit mode when in read/ write).

Before accessing the IFlash module (and consequently also the Flash register to be used for

program/erasing operations), bit ROMEN in SYSCON register shall be set.

During a Flash write operation any attempt to read the flash itself, that is under modification,

will output invalid data (software trap 009Bh). This means that the Flash is not fetchable

when a programming operation is active: the write operation commands must be executed

from another memory (internal RAM or external memory), as in ST10F269 device. In fact,

due to IBUS characteristics, it is not possible to perform a write operation on IFLASH, when

fetching code from IFLASH.

Direct addressing is not allowed for write accesses to IFLASH Control Registers.

During a Write operation, when bit LOCK of FCR0 is set, it is forbidden to write into the

Flash Control Registers.

Power supply drop

If during a write operation the internal low voltage supply drops below a certain internal

voltage threshold, any write operation running is suddenly interrupted and the module is

reset to Read mode. At following Power-on, the interrupted Flash write operation must be

repeated.

ST10F272 数据表(PDF) 29 Page - STMicroelectronics