Silicon Laboratories C8051F342 Flash Electrical Characteristics, Non-volatile Data Storage

C8051F340/1/2/3/4/5/6/7

Table 12.1. Flash Electrical Characteristics

Parameter	Conditions	Min	Typ	Max	Units
Flash Size	C8051F340/2/4/6*	65536*			Bytes
	C8051F341/3/5/7	32768			Bytes
Endurance		20k	100k		Erase/Write
Erase Cycle Time	25 MHz System Clock	10	15	20	ms
Write Cycle Time	25 MHz System Clock	40	55	70	µs

*Note: 1024 bytes at location 0xFC00 to 0xFFFF are reserved.

12.2. 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.

12.3. 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 software can erase Flash memory. Additional security features prevent proprietary program code and data constants 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 512-byte Flash pages, starting at page 0 (addresses 0x0000 to 0x01FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the page containing the Flash Security Lock Byte is also locked when any other Flash pages are locked. See example below.

Security Lock Byte:	11111101b
1’s Complement:	00000010b
Flash pages locked:	3 (2 + Flash Lock Byte Page)
	First two pages of Flash: 0x0000 to 0x03FF
Addresses locked:	Flash Lock Byte Page: (0xFA00 to 0xFBFF for 64k devices; 0x7E00 to
	0x7FFF for 32k devices)

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