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參數(shù)資料
| 型號： | DS87C520-MCL |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Microcontroller |
| 英文描述： | 8-BIT, OTPROM, MICROCONTROLLER, PDIP40 |
| 封裝： | 0.600 INCH, PLASTIC, DIP-40 |
| 文件頁數(shù)： | 13/42頁 |
| 文件大小： | 832K |
| 代理商： | DS87C520-MCL |
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DS87C520/DS83C520
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Both ports can operate simultaneously but can be at different baud rates or even in different modes. The
second serial port has similar control registers (SCON1 at C0h, SBUF1 at C1h) to the original. The new
serial port can only use Timer 1 for timer generated baud rates.
TIMER RATE CONTROL
There is one important difference between the DS87C520/DS83C520 and 8051 regarding timers. The
original 8051 used 12 clocks per cycle for timers as well as for machine cycles. The
DS87C520/DS83C520 architecture normally uses four clocks per machine cycle. However, in the area of
timers and serial ports, the DS87C520/DS83C520 will default to 12 clocks per cycle on reset. This allows
existing code with real-time dependencies such as baud rates to operate properly.
If an application needs higher speed timers or serial baud rates, the user can select individual timers to run
at the 4-clock rate. The Clock Control register (CKCON;8Eh) determines these timer speeds. When the
relevant CKCON bit is a logic 1, the DS87C520/DS83C520 uses 4 clocks per cycle to generate timer
speeds. When the bit is a 0, the DS87C520/DS83C520 uses 12 clocks for timer speeds. The reset
condition is a 0. CKCON.5 selects the speed of Timer 2. CKCON.4 selects Timer 1 and CKCON.3
selects Timer 0. Unless a user desires very fast timing, it is unnecessary to alter these bits. Note that the
timer controls are independent.
POWER-FAIL RESET
The DS87C520/DS83C520 uses a precision band-gap voltage reference to decide if VCC is out of
tolerance. While powering up, the internal monitor circuit maintains a reset state until VCC rises above the
VRST level. Once above this level, the monitor enables the crystal oscillator and counts 65536 clocks. It
then exits the reset state. This power-on reset (POR) interval allows time for the oscillator to stabilize.
A system needs no external components to generate a power-related reset. Anytime VCC drops below
VRST, as in power failure or a power drop, the monitor will generate and hold a reset. It occurs
automatically, needing no action from the software. Refer to the Electrical Specifications for the exact
value of VRST.
POWER-FAIL INTERRUPT
The voltage reference that sets a precise reset threshold also generates an optional early warning Power-
Fail Interrupt (PFI). When enabled by software, the processor will vector to program memory address
0033h if VCC drops below VPFW. PFI has the highest priority. The PFI enable is in the Watchdog Control
SFR (WDCON-D8h). Setting WDCON.5 to a logic 1 will enable the PFI. Application software can also
read the PFI flag at WDCON.4. A PFI condition sets this bit to a 1. The flag is independent of the
interrupt enable and software must manually clear it.
WATCHDOG TIMER
To prevent software from losing control, the DS87C520/DS83C520 includes a programmable Watchdog
Timer. The Watchdog is a free running timer that sets a flag if allowed to reach a preselected time-out. It
can be (re)started by software.
A typical application is to select the flag as a reset source. When the Watchdog times out, it sets its flag
which generates reset. Software must restart the timer before it reaches its time-out or the processor is
reset.
Software can select one of four time-out values. Then, it restarts the timer and enables the reset function.
After enabling the reset function, software must then restart the timer before its expiration or hardware
will reset the CPU. Both the Watchdog Reset Enable and the Watchdog Restart control bits are protected
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS87C520-QNL | 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, PQCC44 |
| DS87C520-QCL | 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, PQCC44 |
| DS87C520-ECL | 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, PQFP44 |
| DS87C520-MNL | 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, PDIP40 |
| DS87C520-ENL | 8-BIT, OTPROM, 33 MHz, MICROCONTROLLER, PQFP44 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS87C520-MCL+ | 功能描述:8位微控制器 -MCU EPROM/ROM High-Speed 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 最大時鐘頻率:50 MHz 程序存儲器大小: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 安裝風格:SMD/SMT |
| DS87C520-MNL | 功能描述:8位微控制器 -MCU EPROM/ROM High-Speed 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 最大時鐘頻率:50 MHz 程序存儲器大小: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 安裝風格:SMD/SMT |
| DS87C520-MNL+ | 功能描述:8位微控制器 -MCU EPROM/ROM High-Speed 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 最大時鐘頻率:50 MHz 程序存儲器大小: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 安裝風格:SMD/SMT |
| DS87C520-QCL | 功能描述:8位微控制器 -MCU EPROM/ROM High-Speed 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 最大時鐘頻率:50 MHz 程序存儲器大小: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 安裝風格:SMD/SMT |
| DS87C520-QCL/T&R | 制造商:Maxim Integrated Products 功能描述:MICRO,OTP,HI SPD 44PLCC 33MHZ TRL - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC MCU EPROM/ROM 33MHZ HS 44PLCC |
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