C8051F303-GSR Silicon Labs, C8051F303-GSR Datasheet - Page 91

• Manufacturer Part Number: C8051F303-GSR
• Description: 8-bit Microcontrollers - MCU 8KB 14Pin MCU
• Manufacturer: Silicon Labs

Specifications of C8051F303-GSR

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit

The lock bits can always be read and cleared to logic 0 regardless of the security settings.
Important note: The only means of removing a lock (write or read/write) once set is to erase the
entire program memory space via a C2 Device Erase command.
The level of Flash security depends on the Flash access method. The three Flash access methods that
can be restricted are reads, writes, and erases from the C2 debug interface, user firmware executing on
unlocked pages, and user firmware executing on locked pages.
Accessing Flash from the C2 debug interface:
1. Any unlocked page may be read, written, or erased.
2. Locked pages cannot be read, written, or erased.
3. The page containing the Lock Byte may be read, written, or erased if it is unlocked.
4. Reading the contents of the Lock Byte is always permitted only if no pages are locked.
5. Locking additional pages (changing ‘1’s to ‘0’s in the Lock Byte) is not permitted.
6. Unlocking Flash pages (changing ‘0’s to ‘1’s in the Lock Byte) requires the C2 Device Erase com-
7. The Reserved Area cannot be read, written, or erased.
organized in 512-byte
mand, which erases all Flash pages including the page containing the Lock Byte and the Lock
Byte itself.
C8051F300/1/2/3
FLASH memory
Lock Byte
Reserved
pages
Bits
7–4
3–0
Figure 10.1. Flash Program Memory Map
0x1E00
0x1DFF
0x1DFE
0x0000
Write Lock: Clearing any of these bits to logic 0 prevents all Flash
memory from being written or page-erased across the C2 interface
Read/Write Lock: Clearing any of these bits to logic 0 prevents all
Flash memory from being read, written, or page-erased across the
C2 interface.
Table 10.2. Security Byte Decoding
organized in 512-byte
FLASH memory
C8051F304
Lock Byte
Reserved
pages
Rev. 2.9
Description
0x1000
0x0FFF
0x0FFE
0x0000
C8051F300/1/2/3/4/5
organized in 512-byte
FLASH memory
C8051F305
Lock Byte
Reserved
pages
0x0800
0x07FF
0x07FE
0x0000
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