C8051F02X Datasheet, PDF (141/272 Pages) Silicon Laboratories – 8K ISP FLASH MCU Family

C8051F020/1/2/3
Figure 15.1. FLASH Program Memory Map and Security Bytes
Read and Write/Erase Security Bits.
(Bit 7 is MSB.)
Bit Memory Block
7 0xE000 - 0xFDFD
6 0xC000 - 0xDFFF
5 0xA000 - 0xBFFF
4 0x8000 - 0x9FFF
3 0x6000 - 0x7FFF
2 0x4000 - 0x5FFF
1 0x2000 - 0x3FFF
0 0x0000 - 0x1FFF
SFLE = 0
Reserved
Read Lock Byte
Write/Erase Lock Byte
0xFFFF
0xFE00
0xFDFF
0xFDFE
0xFDFD
SFLE = 1
Scratchpad Memory
(Data only)
0x007F
0x0000
Program/Data
Memory Space
Software Read Limit
0x0000
FLASH Read Lock Byte
Bits7-0: Each bit locks a corresponding block of memory. (Bit7 is MSB).
0: Read operations are locked (disabled) for corresponding block across the JTAG interface.
1: Read operations are unlocked (enabled) for corresponding block across the JTAG interface.
FLASH Write/Erase Lock Byte
Bits7-0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG interface.
1: Write/Erase operations are unlocked (enabled) for corresponding block across the JTAG interface.
NOTE: When the highest block is locked, the security bytes may be written but not erased.
FLASH access Limit Register (FLACL)
The content of this register is used as the high byte of the 16-bit software read limit address. This 16-
bit read limit address value is calculated as 0xNN00 where NN is replaced by content of this register
on reset. Software running at or above this address is prohibited from using the MOVX and MOVC
instructions to read, write, or erase FLASH locations below this address. Any attempts to read loca-
tions below this limit will return the value 0x00.
The lock bits can always be read and cleared to logic 0 regardless of the security setting applied to the block contain-
ing the security bytes. This allows additional blocks to be protected after the block containing the security bytes has
been locked. Important Note: The only means of removing a lock once set is to erase the entire program mem-
ory space by performing a JTAG erase operation (i.e. cannot be done in user firmware). Addressing either
security byte while performing a JTAG erase operation will automatically initiate erasure of the entire pro-
gram memory space (except for the reserved area). This erasure can only be performed via JTAG. If a non-
security byte in the 0xFBFF-0xFDFF page is addressed during the JTAG erasure, only that page (including the
security bytes) will be erased.
The FLASH Access Limit security feature (see Figure 15.1) protects proprietary program code and data from being
read by software running on the C8051F020/1/2/3. This feature provides support for OEMs that wish to program the
Rev. 1.4
141