AT89LS52-16SC ATMEL [ATMEL Corporation], AT89LS52-16SC Datasheet - Page 21

• Manufacturer Part Number: AT89LS52-16SC
• Description: 8-bit Low-Voltage Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

17. Program Memory Lock Bits
18. Programming the Flash – Parallel Mode
2601B–MICRO–03/05
Table 16-1.
The AT89LS52 has three lock bits that can be left unprogrammed (U) or can be programmed (P)
to obtain the additional features listed in
Table 17-1.
When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset.
If the device is powered up without a reset, the latch initializes to a random value and holds that
value until reset is activated. The latched value of EA must agree with the current logic level at
that pin in order for the device to function properly.
The AT89LS52 is shipped with the on-chip Flash memory array ready to be programmed. The
programming interface needs a high-voltage (12-volt) program enable signal and is compatible
with conventional third-party Flash or EPROM programmers.
The AT89LS52 code memory array is programmed byte-by-byte.
Programming Algorithm: Before programming the AT89LS52, the address, data, and control
signals should be set up according to the Flash programming mode table
ure 20-1
Mode
Idle
Idle
Power-down
Power-down
1. Input the desired memory location on the address lines.
2. Input the appropriate data byte on the data lines.
3. Activate the correct combination of control signals.
4. Raise EA/V
5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The byte-
1
2
3
4
write cycle is self-timed and typically takes no more than 50 µs. Repeat steps 1
through 5, changing the address and data for the entire array or until the end of the
object file is reached.
Program Lock Bits
and
LB1
U
P
P
P
Figure
Status of External Pins During Idle and Power-down Modes
Lock Bit Protection Modes
Program Memory
Internal
External
Internal
External
PP
LB2
U
U
P
P
to 12V.
20-2. To program the AT89LS52, take the following steps:
LB3
U
U
U
P
Protection Type
No program lock features
MOVC instructions executed from external program memory are
disabled from fetching code bytes from internal memory, EA is
sampled and latched on reset, and further programming of the
Flash memory is disabled
Same as mode 2, but verify is also disabled
Same as mode 3, but external execution is also disabled
ALE
1
1
0
0
Table
PSEN
17-1.
1
1
0
0
PORT0
Float
Float
Data
Data
PORT1
Data
Data
Data
Data
(Table
AT89LS52
Address
PORT2
Data
Data
Data
20-1) and
PORT3
Data
Data
Data
Data
Fig-
21