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Reading the Signature Bytes
Parallel Programming
Characteristics
AT90S2313
68
The algorithm for reading the signature bytes is as follows (refer to "Programming the
Flash" on page 64 for details on command and address loading):
1. A: Load Command "0000 1000".
2. C: Load Address Low Byte ($00 - $02).
Set OE to "0", and BS to "0". The selected signature byte can now be read at DATA.
3. Set OE to "1".
Figure 52. Parallel Programming Timing
XTAL1
t
DVXH
Data & Contol
(DATA, XA0/1, BS)
WR
RDY/BSY
OE
DATA
Table 26. Parallel Programming Characteristics, T
Symbol
Parameter
V
Programming Enable Voltage
PP
I
Programming Enable Current
PP
t
Data and Control Setup before XTAL1 High
DVXH
t
XTAL1 Pulse Width High
XHXL
t
Data and Control Hold after XTAL1 Low
XLDX
t
XTAL1 Low to WR Low
XLWL
t
BS Valid to WR Low
BVWL
t
BS Hold after RDY/BSY High
RHBX
t
WR Pulse Width Low
WLWH
t
WR High to RDY/BSY Low
WHRL
t
WR Low to RDY/BSY High
WLRH
t
XTAL1 Low to OE Low
XLOL
t
OE Low to DATA Valid
OLDV
t
OE High to DATA Tri-stated
OHDZ
t
WR Pulse Width Low for Chip Erase
WLWH_CE
WR Pulse Width Low for Programming the Fuse
t
Bits
WLWH_PFB
Notes:
1. Use t
for chip erase and t
WLWH_CE
2. If t
is held longer than t
WLWH
t
XLWL
t
XHXL
t
t
XLDX
BVWL
t
WLWH
t
XLOL
t
OLDV
= 25°C ± 10%, V
A
(1)
(2)
(2)
for programming the Fuse bits.
WLWH_PFB
, no RDY/BSY pulse will be seen.
WLRH
t
RHBX
t
WHRL
t
WLRH
t
OHDZ
= 5V ± 10%
CC
Min
Typ
Max
11.5
12.5
250.0
67.0
67.0
67.0
67.0
67.0
67.0
67.0
20.0
0.5
0.7
0.9
67.0
20.0
20.0
5.0
10.0
15.0
1.0
1.5
1.8
0839G–08/01
Units
V
µA
ns
ns
ns
ns
ns
ns
ns
ns
ms
ns
ns
ns
ms
ms
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