Flash Memory Control; Flash Memory Command Sequence Execution Control (Flscr<Flsmd>); Flash Memory Bank Select Control (Flscr<Banksel>) - Philips CEM2100/00 Service Manual

19. Flash Memory

19.1 Flash Memory Control

19.1 Flash Memory Control
The flash memory is controlled via the flash memory control register (FLSCR) .
Flash Memory Control Register
FLSCR 7
(0FFFH)
FLSMD
BANKSEL
Note 1: The command sequence of the flash memory can be executed only when FLSMD="0011B". In other cases, any attempts
to execute the command sequence are ineffective.
Note 2: FLSMD must be set to either "1100B" or "0011B".
Note 3: BANKSEL is effective only in the serial PROM mode. In the MCU mode, the flash memory is always accessed with actual
addresses (1000-FFFFH) regardless of BANKSEL.
Note 4: Bits 2 through 0 in FLSCR are always read as don't care.
19.1.1 Flash Memory Command Sequence Execution Control (FLSCR<FLSMD>)
The flash memory can be protected from inadvertent write due to program error or microcontroller misoper-
ation. This write protection feature is realized by disabling flash memory command sequence execution via the
flash memory control register (write protect). To enable command sequence execution, set FLSCR<FLSMD>
to "0011B". To disable command sequence execution, set FLSCR<FLSMD> to "1100B". After reset,
FLSCR<FLSMD> is initialized to "1100B" to disable command sequence execution. Normally,
FLSCR<FLSMD> should be set to "1100B" except when the flash memory needs to be written or erased.
19.1.2 Flash Memory Bank Select Control (FLSCR<BANKSEL>)
In the serial PROM mode, a 2-kbyte BOOTROM is mapped to addresses 7800H-7FFFH and the flash mem-
ory is mapped to 2 banks at 8000H-FFFFH. Flash memory addresses 1000H-7FFFH are mapped to 9000H-
FFFFH as BANK0, and flash memory addresses 8000H-FFFFH are mapped to 8000H-FFFFH as BANK1.
FLSCR<BANKSEL> is used to switch between these banks. For example, to access the flash memory address
7000H, set FLSCR<BANKSEL> to "0" and then access F000H. To access the flash memory address 9000H,
set FLSCR<BANKSEL> to "1" and then access 9000H.
In the MCU mode, the flash memory is accessed with actual addresses at 1000H-FFFFH. In this case,
FLSCR<BANKSEL> is ineffective (i.e., its value has no effect on other operations).
Table 19-1 Flash Memory Access
Serial PROM mode
6 5
FLSMD
Flash memory command sequence exe-
cution control
Flash memory bank select control
(Serial PROM mode only)
FLSCR
Operating Mode
<BANKSEL>
MCU mode Don't care
0
(BANK0)
1
(BANK1)
4 3 2
BANKSEL
1100: Disable command sequence execution
0011: Enable command sequence execution
Others: Reserved
0: Select BANK0
1: Select BANK1
Access Area
1000H-FFFFH
1000H-7FFFH
8000H-FFFFH
Page 224
T5CL8
1 0
(Initial value : 1100 1***)
Specified Address
9000H-FFFFH
R/W
R/W