AT87F52-12AI ATMEL Corporation, AT87F52-12AI Datasheet - Page 12

• Manufacturer Part Number: AT87F52-12AI
• Description: 8-Bit Microcontroller with 8K Bytes QuickFlash
• Manufacturer: ATMEL Corporation

Program Memory Lock Bits
The AT87F52 has three lock bits that can be left unpro-
grammed (U) or can be programmed (P) to obtain the addi-
tional features listed in the following table.
Lock Bit Protection Modes
When lock bit 1 is programmed, the logic level at the EA pin
is sampled and latched during reset. If the device is pow-
ered 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.
Programming the QuickFlash
The AT87F52 is shipped with the on-chip QuickFlash mem-
ory array ready to be programmed. The programming inter-
face needs a high-voltage (12-volt) program enable signal
and is compatible with conventional third-party Flash or
EPROM programmers.
The AT87F52 code memory array is programmed byte-by-
byte.
12
1
2
3
4
Program Lock Bits
LB1
U
P
P
P
LB2
U
U
P
P
LB3
U
U
U
P
AT87F52
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 QuickFlash memory is
disabled.
Same as mode 2, but verify is
also disabled.
Same as mode 3, but external
execution is also disabled.
Programming Algorithm: Before programming the
AT87F52, the address, data, and control signals should be
set up according to the QuickFlash programming mode
table and Figures 9 and 10. To program the AT87F52, take
the following steps:
1. Input the desired memory location on the address
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 Quick-
Data Polling: The AT87F52 features Data Polling to indi-
cate the end of a write cycle. During a write cycle, an
attempted read of the last byte written will result in the com-
plement of the written data on PO.7. Once the write cycle
has been completed, true data is valid on all outputs, and
the next cycle may begin. Data Polling may begin any time
after a write cycle has been initiated.
Ready/Busy: The progress of byte programming can also
be monitored by the RDY/BSY output signal. P3.4 is pulled
low after ALE goes high during programming to indicate
BUSY. P3.4 is pulled high again when programming is
done to indicate READY.
Program Verify: If lock bits LB1 and LB2 have not been
programmed, the programmed code data can be read back
via the address and data lines for verification. The lock bits
cannot be verified directly. Verification of the lock bits is
achieved by observing that their features are enabled.
Reading the Signature Bytes: The signature bytes are
read by the same procedure as a normal verification of
locations 030H, 031H, and 032H, except that P3.6 and
P3.7 must be pulled to a logic low. The values returned are
as follows.
lines.
Flash array or the lock bits. The byte-write cycle is self-
timed and typically takes no more than 1.5 ms. Repeat
steps 1 through 5, changing the address and data for
the entire array or until the end of the object file is
reached.
(030H) = 1EH indicates manufactured by Atmel
(031H) = 87H indicates 87F family
(032H) = 02H indicates 87F52
PP
to 12V.