DS87C530_1 Datasheet, PDF (26/44 Pages) Dallas Semiconductor – EPROM/ROM Micro with Real Time Clock

EXIF.0
WDCON.6
WDCON.1
WDCON.0
WDCON.3
ROMSIZE.2
ROMSIZE.1
ROMSIZE.0
TRIM.7-0
RTCC.2
RTCC.0
BGS
POR
EWT
RWT
WDIF
RMS2
RMS1
RMS0
RTCWE
RTCE
Band-gap Select
Power-on Reset flag
Enable Watchdog Reset
Restart Watchdog
Watchdog Interrupt Flag
ROM size select 2
ROM size select 1
ROM size select 0
All RTC trim functions
RTC Write Enable
RTC Oscillator Enable
DS87C530/DS83C530
EPROM PROGRAMMING
The DS87C530 follows standards for a 16-kbyte EPROM version in the 8051 family. It is available in a
UV erasable, ceramic windowed package and in plastic packages for one-time user-programmable
versions. The part has unique signature information so programmers can support its specific EPROM
options.
PROGRAMMING PROCEDURE
The DS87C530 should run from a clock speed between 4 and 6 MHz when programmed. The
programming fixture should apply address information for each byte to the address lines and the data
value to the data lines. The control signals must be manipulated as shown in Table 10. The diagram in
Figure 5 shows the expected electrical connection for programming. Note that the programmer must
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 DS87C530 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 five times for EPROM array and 25 times for encryption table, lock bits, and
other EPROM bits,
6. Repeat as many times as necessary.
SECURITY OPTIONS
The DS87C530 employs a standard three-level lock that restricts viewing of the EPROM contents. A 64-
byte Encryption Array allows the authorized user to verify memory by presenting the data in encrypted
form.
Lock Bits
The security lock consists of 3 lock bits. These bits select a total of 4 levels of security. Higher levels
provide increasing security but also limit application flexibility. Table 11 shows the security settings.
Note that the programmer cannot directly read the state of the security lock. User software has access to
this information as described in the Memory section.
Encryption Array
The Encryption Array allows an authorized user to verify EPROM without allowing the true memory to
be dumped. During a verify, each byte is Exclusive NORed (XNOR) with a byte in the Encryption Array.
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