AN1176 STMicroelectronics, AN1176 Datasheet - Page 21

• Manufacturer Part Number: AN1176
• Description: 68HC11/PSD813F1 DESIGN GUIDE
• Manufacturer: STMicroelectronics

3.2.2 Memory Map Configuration During Normal Application
Figure 6 shows the memory map after the 68HC11 has set the SWAP bit to logic one. At this
point, the 68HC11 can download new ISP loader code to EEPROM segments EES0/EES1 if
needed. The 68HC11 must first set the UNLOCK bit to logic one before updating ISP loader
code. The UNLOCK bit is another one of the eight internal PSD page register bits. In this final
configuration, the 68HC11 has available:
Each time this 68HC11 system gets reset or goes through a power-on cycle, the PSD presents the
memory map of Figure 5 to the MCU, and the boot sequence is repeated.
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48K bytes of main flash memory in the common area (9000h-FFFFh)
96K bytes of main flash across three pages of lower memory (0000h-7FFFh)
2K bytes of SRAM in addition to the SRAM that resides on the 68HC11
16K bytes of EEPROM for general data storage on memory page 3
16K bytes of EEPROM for ISP loader code.
(any page )
C O M M O N
Figure 6 – Memory Map, Enhanced Design, Normal Operation
R EG IO N
R EG IO N
PAG ED
F FF F
C 00 0
8A00
820 0
800 0
400 0
000 0
8B00
900 0
RS O , 2K bytes S R A M
CS IO P, P S D C ontrol
68H C11 Regs/RAM
MEMO RY MAP AFT ER SW APPING ISP LOADER COD E
SYS T EM I/O
16K bytes
12K bytes
16K bytes
16K bytes
FS7
FS0
FS2
FS1
000 0
F inal con figuration after M C U sets S W AP bit = 1
F lash
F lash
F lash
F lash
PAG E 0
000 0
16K bytes
16K bytes
FS4
FS3
F lash
F lash
1) S W A P b it = 1.
2) N ow th e M C U boo t area is occupied by
3) M C U can do wnloa d n ew IS P loade r code
4) M C U can use E E S2 /E E S 3 for gene ral
PAG E 1
m ain fla sh m em ory inste ad of E E PR O M .
d ata storage .
in to E E S0 /E E S 1 a fter se tting the
U N LO C K b it = 1.
800 0
16K bytes
16K bytes
FS6
FS5
F lash
F lash
PAG E 2
800 0
EES1
EES2
E E P R O M
E E P R O M
EES0
E E P R O M
8K bytes
EES3
8K bytes
E E P R O M
8K bytes
8K bytes
PAG E 3
800 0
400 0
200 0
000 0