C8051F961-A-GM Silicon Labs, C8051F961-A-GM Datasheet - Page 247

• Manufacturer Part Number: C8051F961-A-GM
• Description: 8-bit Microcontrollers - MCU 128KB, DC-DC, LCD AES, QFN40
• Manufacturer: Silicon Labs

Specifications of C8051F961-A-GM

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 25 MHz
• Program Memory Size: 128 KB
• Data Ram Size: 8448 B
• On-chip Adc: Yes
• Operating Supply Voltage: 2.5 V to 3.3 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: QFN-40
• Mounting Style: SMD/SMT
• Number Of Programmable I/os: 34
• Number Of Timers: 4

18.2. Non-volatile Data Storage
The flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written using the MOVX
write instruction and read using the MOVC instruction. Note: MOVX read instructions always target XRAM.
18.3. Security Options
The CIP-51 provides security options to protect the flash memory from inadvertent modification by soft-
ware as well as to prevent the viewing of proprietary program code and constants. The Program Store
Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register
PSCTL) bits protect the flash memory from accidental modification by software. PSWE must be explicitly
set to 1 before software can modify the flash memory; both PSWE and PSEE must be set to 1 before soft-
ware can erase flash memory. Additional security features prevent proprietary program code and data con-
stants from being read or altered across the C2 interface.
A Security Lock Byte located at the last byte of flash user space offers protection of the flash program
memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The flash security
mechanism allows the user to lock n 1024-byte flash pages, starting at page 0 (addresses 0x0000 to
0x03FF), where n is the 1s complement number represented by the Security Lock Byte. The page con-
taining the Flash Security Lock Byte is unlocked when no other flash pages are locked (all bits of
the Lock Byte are 1) and locked when any other flash pages are locked (any bit of the Lock Byte is
0). See example in Figure 18.1
The 128 kB flash devices (C8051F960/1/2/3) do not have a reserved area. The lock byte is at the top of
the flash area (0x1FFFF). Writing 0x80 to the lock byte of the 128 kB devices will lock the entire flash. Writ-
ing 0x00 to the 128 kB flash devices will prevent future erases.
Flash pages locked:
Security Lock Byte:
ones Complement:
any other FLASH
pages are locked
according to the
Access limit set
FLASH security
Locked when
lock byte
Figure 18.1. Flash Security Example
3 (First two flash pages + Lock Byte Page)
Unlocked FLASH Pages
Rev. 0.5
Locked Flash Pages
Lock Byte Page
Reserved Area
Lock Byte
00000010b
11111101b
C8051F96x
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