DS87C550 Datasheet, PDF (31/50 Pages) Dallas Semiconductor – EPROM High-Speed Micro with A/D and PWM

DS87C550
apply addresses in demultiplexed fashion to Ports 1 and 2 with data on Port 0. Waveforms and timing are
provided in the Electrical Specifications.
Program the DS87C550 as follows:
1. Apply the address value.
2. Apply the data value.
3. Select the programming option from Table 10 using the control signals.
4. Increase the voltage on V_PP from 5V to 12.75V if writing to the EPROM.
5. Pulse the ^PROG signal 5 times for EPROM array and 25 times for encryption table, lock bits, and
other EPROM bits.
6. Repeat as many times as necessary.
EPROM PROGRAMMING MODES Table 10
MODE
Program Code Data
RST PSEN
H
L
ALE/
PROG
PL5*
EA/
V_PP
12.75
V
Verify Code Data
H
L
H
H
Program Encryption Array H
L
Address 0-3Fh
Program Lock Bits LB1 ^H
L
PL25*
PL25*
12.75
V
12.75
V
LB2 ^H
L
PL25*
12.75
V
LB3 ^H
L
PL25*
12.75
V
Program Option Register
H
L
Address FCh
PL25*
12.75
V
Read Signature or Option H
L
H
H
Register 30, 31, 60, FCh
*PLn indicates pulse to a logic low n times
P2.6 P2.7 P3.3 P3.6 P3.7
L
H
H
H
H
L
L
L
H
H
L
H
H
L
H
H
H
H
H
H
H
H
H
L
L
H
L
H
H
L
L
H
H
L
L
L
L
L
L
L
EPROM LOCK BITS Table 11
Level
Lock Bits
Protection
LB1 LB2 LB3
1
U
U
U No program lock. Encrypted; verify if Encryption table was programmed.
Prevent MOVC instructions in external memory from reading program
2
P U U bytes in internal memory. EA is sampled and latched on reset. Allow
no further programming of EPROM.
3
P
P
U
Level 2 plus no verify operation. Also, prevents MOVX instructions in external
memory from reading SRAM (MOVX) in internal memory.
4
P
P
P Level 3 plus no external execution.
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