at89lv55 ATMEL Corporation, at89lv55 Datasheet - Page 18

• Manufacturer Part Number: at89lv55
• Description: At89lv55 8-bit Microcontroller With 20k Bytes Flash
• Manufacturer: ATMEL Corporation

18
AT89LV55
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 ver-
ified directly. Verification of the lock bits is achieved by observing that their features are enabled.
Figure 17-1. Programming the Flash Memory
Chip Erase: The entire Flash array is erased electrically by using the proper combination of
control signals and by holding ALE/PROG low for 10 ms. The code array is written with all 1s.
The chip erase operation must be executed before the code memory can be reprogrammed.
Reading the Signature Bytes: The signature bytes are read by the same procedure as a nor-
mal verification of locations 030H, and 031H, except that P3.6 and P3.7 must be pulled to a logic
low. The values returned are as follows:
(030H) = 1EH indicates manufactured by Atmel
(031H) = 65H indicates 89LV55
(032H) = FFH indicates 12V programming
PROGRAMMING
MODES TABLE
*Programming address line A14 (P3.0) is not the same
as the external memory address line A14 (P2.6)
SEE FLASH
3-12 MHz
0000H/4FFFH
ADDR.
A8 - A13
A14*
A0 - A7
P1.0 - P1.7
P2.0 - P2.5
P3.0
P2.6
P2.7
P3.6
P3.7
XTAL2
XTAL1
GND
AT89LV55
PSEN
RST
ALE
V
EA
P0
CC
+5V
PGM
DATA
PROG
V /V
V
I H
I H
PP
0811D–MICRO–3/06