AT80F51-12AI ATMEL [ATMEL Corporation], AT80F51-12AI Datasheet - Page 5

• Manufacturer Part Number: AT80F51-12AI
• Description: 8-Bit Microcontroller with 4K Bytes QuickFlash Memory
• Manufacturer: ATMEL [ATMEL Corporation]

nated. The only exit from power down is a hardware reset.
Reset redefines the SFRs but does not change the on-chip
RAM. The reset should not be activated before V
restored to its normal operating level and must be held
active long enough to allow the oscillator to restart and sta-
bilize.
Program Memory Lock Bits
On the chip are three lock bits which can be left unpro-
grammed (U) or can be programmed (P) to obtain the addi-
tional features listed in the table below:
Lock Bit Protection Modes
Programming/Verifying the QuickFlash
The AT80F51 can only be programmed by Atmel. Cus-
tomer codes should be submitted in duplicate on a floppy
disk or uploaded to Atmel’s bulletin board or Web site. The
code should be in the Intel Hex format. The desired states
of the Lock Bits should be specified. Once programmed,
the code memory and Lock Bits cannot be erased or repro-
grammed.
Please consult the factory or Atmel’s representatives for
details on submitting custom codes.
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
QuickFlash Verification Modes
Mode
Read Code Data
Read Signature Byte
1
2
3
4
Program Lock Bits
LB1
U
P
P
P
LB2
U
U
P
P
LB3
U
U
U
P
RST
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 is disabled.
Same as mode 2, also verify is disabled.
Same as mode 3, also external execution is disabled.
H
H
PSEN
L
L
CC
is
ALE
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. It is nec-
essary that the latched value of EA be in agreement with
the current logic level at that pin in order for the device to
function properly.
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.
H
H
(030H) = 1EH indicates manufactured by Atmel
(031H) = 80H indicates QuickFlash
(032H) = 01H indicates AT80F51
EA
H
H
P2.6
L
L
P2.7
L
L
P3.6
H
L
P3.7
H
L
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