TS87C54X2-VCB Atmel, TS87C54X2-VCB Datasheet - Page 36

• Manufacturer Part Number: TS87C54X2-VCB
• Description: IC MCU 8BIT 16K OTP 40MHZ 44PLCC
• Manufacturer: Atmel
• Series: 87Cr

Specifications of TS87C54X2-VCB

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 40/30MHz
• Connectivity: UART/USART
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: OTP
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Data Converters: -

16. TS80C54/58X2 ROM
16.1
16.2
16.2.1
16.2.2
16.2.3
16.2.4
36
ROM Structure
ROM Lock System
AT/TS8xC54/8X2
Signature bytes
Verify Algorithm
Encryption Array
Program Lock Bits
The TS80C54/58X2 ROM memory is in three different arrays:
The program Lock system, when programmed, protects the on-chip program against software
piracy.
Within the ROM array are 64 bytes of encryption array that are initially unprogrammed (all FF’s).
Every time a byte is addressed during program verify, 6 address lines are used to select a byte
of the encryption array. This byte is then exclusive-NOR’ed (XNOR) with the code byte, creating
an encrypted verify byte. The algorithm, with the encryption array in the unprogrammed state,
will return the code in its original, unmodified form.
When using the encryption array, one important factor needs to be considered. If a byte has the
value FFh, verifying the byte will produce the encryption byte value. If a large block (>64 bytes)
of code is left unprogrammed, a verification routine will display the content of the encryption
array. For this reason all the unused code bytes should be programmed with random values.
This will ensure program protection.
The lock bits when programmed according to Table 16-1. will provide different level of protection
for the on-chip code and data.
Table 16-1.
U: unprogrammed
P: programmed
The TS80C54/58X2 contains 4 factory programmed signatures bytes. To read these bytes, per-
form the process described in section 8.3.
Refer to 17.3.4
Security
• the code array:16/32 Kbytes.
• the encryption array:64 bytes.
• the signature array:4 bytes.
level
1
2
Program Lock Bits
LB1
U
P
Program Lock bits
LB2
U
U
LB3
U
U
No program lock features enabled. Code verify will still be encrypted by
the encryption array if programmed. MOVC instruction executed from
external program memory returns non encrypted data.
MOVC instruction executed from external program memory are disabled
from fetching code bytes from internal memory, EA is sampled and
latched on reset.
Protection Description
4431E–8051–04/06