DS87C530_1 Datasheet, PDF (27/44 Pages) Dallas Semiconductor – EPROM/ROM Micro with Real Time Clock

DS87C530/DS83C530
This results in a true representation of the EPROM while the Encryption is unprogrammed (FFh). Once
the Encryption Array is programmed in a non-FFh state, the verify value will be encrypted.
For encryption to be effective, the Encryption Array must be unknown to the party that is trying to verify
memory. The entire EPROM also should be a non-FFh state or the Encryption Array can be discovered.
The Encryption Array is programmed as shown in Table 10. Note that the programmer can not read the
array. Also note that the verify operation always uses the Encryption Array. The array has no impact
while FFh. Simply programming the array to a non-FFh state will cause the encryption to function.
OTHER EPROM OPTIONS
The DS87C530 has user selectable options that must be set before beginning software execution. These
options use EPROM bits rather than SFRs.
Program the EPROM selectable options as shown in Table 10. The Option Register sets or reads these
selections. The bits in the Option Control Register have the following function:
Bit 7 -4 Reserved, program to a 1.
Bit 3 Watchdog POR default. Set=1; Watchdog reset function is disabled on power-up. Set=0; Watchdog
reset function is enabled automatically.
Bit 2-0 Reserved. Program to a 1.
SIGNATURE
The Signature bytes identify the product and programming revision to EPROM programmers. This
information is at programming addresses 30h, 31h, and 60h. This information is as follows::
Address
30h
31h
60h
Value
DAh
30h
01h
Meaning
Manufacturer
Model
Extension
EPROM PROGRAMMING MODES Table 10
MODE
RST PSEN ALE/ PROG EA/VPP P2.6 P2.7 P3.3 P3.6 P3.7
Program Code Data H
L
PL
12.75V L H H H H
Verify Code Data
H
L
H
H
L L LHH
Program Encryption H
L
Array Address 0-3Fh
PL
12.75V L H H L H
Program Lock LB1 H
L
Bits
LB2 H
L
PL
12.75V H H H H H
PL
12.75V H H H L L
LB3 H
L
PL
12.75V H L H H L
Program Option
H
L
Register Address FCh
PL
12.75V L H H L L
Read Signature or
H
L
H
Option Registers 30,
31, 60, FCh
H
LLLLL
* PL indicates pulse to a logic low.
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