C8051F120DK Silicon Laboratories Inc, C8051F120DK Datasheet - Page 203

• Manufacturer Part Number: C8051F120DK
• Description: DEVKIT-F120/21/22/23/24/25/26/27
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F120DK

• Contents: Evaluation Board, Power Supply, USB Cables, Adapter and Documentation
• Processor To Be Evaluated: C8051F12x and C8051F13x
• Interface Type: USB
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F120
• Silicon Family Name: C8051F12x
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: C8051F120, 121, 122, 123, 124, 125, 126, 127
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1224

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
15.2. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as prevent the viewing of proprietary program code and constants. The Program Store Write
Enable (PSCTL.0), Program Store Erase Enable (PSCTL.1), and Flash Write/Erase Enable (FLACL.0) bits
protect the Flash memory from accidental modification by software. These bits must be explicitly set to
logic 1 before software can write or erase the Flash memory. Additional security features prevent proprie-
tary program code and data constants from being read or altered across the JTAG interface or by software
running on the system controller.
A set of security lock bytes protect the Flash program memory from being read or altered across the JTAG
interface. Each bit in a security lock-byte protects one 16k-byte block of memory. Clearing a bit to logic 0 in
the Read Lock Byte prevents the corresponding block of Flash memory from being read across the JTAG
interface. Clearing a bit in the Write/Erase Lock Byte protects the block from JTAG erasures and/or writes.
The Scratchpad area is read or write/erase locked when all bits in the corresponding security byte are
cleared to logic 0.
On the C8051F12x and C8051F130/1, the security lock bytes are located at 0x1FBFE (Write/Erase Lock)
and 0x1FBFF (Read Lock), as shown in Figure 15.2. On the C8051F132/3, the security lock bytes are
located at 0x0FFFE (Write/Erase Lock) and 0x0FFFF (Read Lock), as shown in Figure 15.3. The 1024-
byte sector containing the lock bytes can be written to, but not erased, by software. An attempted read of a
read-locked byte returns undefined data. Debugging code in a read-locked sector is not possible through
the JTAG interface. The lock bits can always be read from and written to logic 0 regardless of the security
setting applied to the block containing the security bytes. This allows additional blocks to be protected after
the block containing the security bytes has been locked.
Important Note: To ensure protection from external access, the block containing the lock bytes
must be Write/Erase locked. On the 128 kB devices (C8051F12x and C8051F130/1), the block con-
taining the security bytes is 0x18000-0x1BFFF, and is locked by clearing bit 7 of the Write/Erase
Lock Byte.
On the 64 kB devices (C8051F132/3), the block containing the security bytes is
0x0C000-0x0FFFF, and is locked by clearing bit 3 of the Write/Erase Lock Byte. If the page contain-
ing the security bytes is not Write/Erase locked, it is still possible to erase this page of Flash mem-
ory through the JTAG port and reset the security bytes.
When the page containing the security bytes has been Write/Erase locked, a JTAG full device erase
must be performed to unlock any areas of Flash protected by the security bytes. A JTAG full
device erase is initiated by performing a normal JTAG erase operation on either of the security byte
locations. This operation must be initiated through the JTAG port, and cannot be performed from
firmware running on the device.
Rev. 1.4
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