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參數(shù)資料
| 型號(hào)： | DS87C530-ENL |
| 英文描述： | EPROM MICRO WITH REAL TIME CLOCK |
| 中文描述： | 微型存儲(chǔ)器與實(shí)時(shí)時(shí)鐘 |
| 文件頁(yè)數(shù)： | 23/40頁(yè) |
| 文件大?。?/td> | 435K |
| 代理商： | DS87C530-ENL |
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DS87C530
022197 23/40
TIMED ACCESS PROTECTION
It is useful to protect certain SFR bits from an accidental
write operation. The Timed Access procedure stops an
errant CPU from accidentally changing these bits. It
requires that the following instructions precede a write
of a protected bit.
MOV
MOV
0C7h, #0AAh
0C7h, #55h
Writing an AAh then a 55h to the Timed Access register
(location C7h) opens a 3 cycle window for write access.
The window allows software to modify a protected bit(s).
If these instructions do not immediately precede the
write operation, then the write will not take effect. The
protected bits are:
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
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
RTCWE RTC Write Enable
RTCE
RTC Oscillator Enable
EPROM PROGRAMMING
The DS87C530 follows standards for a 16K byte
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 program-
mers 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 fix-
ture 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 three 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 pro-
grammer 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. This results
in a true representation of the EPROM while the Encryp-
tion 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.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS87C530-KCL | EPROM MICRO WITH REAL TIME CLOCK |
| DS87C530-QNL | EPROM MICRO WITH REAL TIME CLOCK |
| DS87C550 | EPROM High-Speed Micro with A/D and PWM |
| DS87C550-QCL | EPROM High-Speed Micro with A/D and PWM |
| DS87C550-FCL | EPROM High-Speed Micro with A/D and PWM |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS87C530-ENL+ | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:EPROM/ROM Microcontrollers with Real-Time Clock |
| DS87C530-KCL | 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
| DS87C530-QCL | 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
| DS87C530-QCL+ | 功能描述:8位微控制器 -MCU EPROM MCU w/RTC RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時(shí)鐘頻率:50 MHz 程序存儲(chǔ)器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT |
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