SAB88C166 Datasheet, PDF (14/58 Pages) Siemens Semiconductor Group – 16-Bit CMOS Single-Chip Microcontrollers with/without oscillator prescaler with 32 KByte Flash EPROM

SAB 88C166(W)
Operation Modes of the Flash Memory
There are two basic operation modes for Flash accesses: The standard and the writing mode. Sub-
modes of the writing mode are the programming, the erase and the non-verify mode.
Figure 4
Flash Operating Mode Transitions
In Standard Mode the Flash memory can be accessed from any memory location (external
memory, on-chip RAM or Flash memory) for instruction fetches and data operand reads. Data
operand reads may use both direct 16-bit (mnemonic: mem) and indirect (mnemonic: [Rw])
addressing modes. Standard mode does not allow accesses to the FCR or Flash write operations.
Note: When Flash protection is active, data operands can be accessed only by instructions that are
executed out of the internal Flash memory.
The Flash Writing Modes must be entered for programming or erasing the Flash memory. The
SAB 88C166 enters these modes by a specific key code sequence, called UNLOCK sequence.
In writing mode the used addressing mode decides whether the FCR or a Flash memory location is
accessed. The FCR can be accessed with any direct access to an even address in the active
address space of the Flash memory. Only word operand instructions are allowed for FCR accesses.
Accesses to Flash memory locations must use indirect addressing to even addresses.
direct 16-bit addressing mode: mem -->
indirect addressing mode:
[Rw_n] -->
Access to FCR
Access to Flash location
Semiconductor Group
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