SST89V516RD2-33-C-NJE Просмотр технического описания (PDF) - Microchip Technology
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SST89V516RD2-33-C-NJE Datasheet PDF : 94 Pages
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FlashFlex MCU
SST89E516RD2 / SST89E516RD
SST89V516RD2 / SST89V516RD
Data Sheet
Program Memory Block Switching
The program memory block switching feature of the device allows either Block 1 or the lowest 8 KByte of
Block 0 to be used for the lowest 8 KByte of the program address space. SFCF[1:0] controls program
memory block switching.
Table 2: SFCF Values for Program Memory Block Switching
SFCF[1:0]
01, 10, 11
00
Program Memory Block Switching
Block 1 is not visible to the program counter (PC).
Block 1 is reachable only via in-application programming from 0000H - 1FFFH.
Block 1 is overlaid onto the low 8K of the program address space; occupying address locations 0000H -
1FFFH.
When the PC falls within 0000H - 1FFFH, the instruction will be fetched from Block 1 instead of Block 0.
Outside of 0000H - 1FFFH, Block 0 is used. Locations 0000H - 1FFFH of Block 0 are reachable through
in-application programming.
T0-0.0 25093
Reset Configuration of Program Memory Block Switching
Program memory block switching is initialized after reset according to the state of the Start-up Config-
uration bit SC0. The SC0 bit is programmed via an external host mode command or an IAP Mode com-
mand. See Table 14.
Once out of reset, the SFCF[0] bit can be changed dynamically by the program for desired effects.
Changing SFCF[0] will not change the SC0 bit.
Caution must be taken when dynamically changing the SFCF[0] bit. Since this will cause different
physical memory to be mapped to the logical program address space. The user must avoid executing
block switching instructions within the address range 0000H to 1FFFH.
Table 3: SFCF Values Under Different Reset Conditions
SC01
U (1)
P (0)
Power-on
or
External
Reset
00
(default)
01
State of SFCF[1:0] after:
WDT Reset
or
Brown-out
Reset
x0
x1
1. P = Programmed (Bit logic state = 0),
U = Unprogrammed (Bit logic state = 1)
Software
Reset
10
11
T0-0.0 25093
Data RAM Memory
The data RAM has 1024 bytes of internal memory. The RAM can be addressed up to 64KB for external
data memory.
©2013 Silicon Storage Technology, Inc.
12
DS25093B
02/13
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