参数资料
型号: DS89C440-QNG
厂商: Maxim Integrated Products
文件页数: 31/46页
文件大小: 0K
描述: IC MCU FLASH 32KB 25MHZ 44-PLCC
标准包装: 26
系列: 89C
核心处理器: 8051
芯体尺寸: 8-位
速度: 25MHz
连通性: EBI/EMI,SIO,UART/USART
外围设备: 电源故障复位,WDT
输入/输出数: 32
程序存储器容量: 32KB(32K x 8)
程序存储器类型: 闪存
RAM 容量: 1K x 8
电压 - 电源 (Vcc/Vdd): 4.5 V ~ 5.5 V
振荡器型: 外部
工作温度: -40°C ~ 85°C
封装/外壳: 44-LCC(J 形引线)
包装: 管件
DS89C430/DS89C450 Ultra-High-Speed Flash Microcontrollers
37 of 46
Timer/Counters
The DS89C430 incorporates three 16-bit timers. All three timers can be used as either counters of external events,
where 1-to-0 transitions on a port pin are monitored and counted, or timers that count oscillator cycles. Table 12
summarizes the timer functions.
Timers 0 and 1 both have three modes of operations. They can each be used as a 13-bit timer/counter, a 16-bit
timer/counter, or an 8-bit timer/counter with autoreload. Timer 0 has a fourth operating mode as two 8-bit
timer/counters without autoreload. Each timer can also be used as a counter of external pulses on the
corresponding T0/T1 pin for 1-to-0 transitions. The timer mode (TMOD) register controls the mode of operation.
Each timer consists of a 16-bit register in 2 bytes, which can be found in the SFR map as TL0, TH0, TL1, and TH1.
The timer control (TCON) register enables timers 0 and 1.
Table 12. Timer Functions
FUNCTIONS
TIMER 0
TIMER 1
TIMER 2
Timer/Counter
13/16/8*/2x8 bit
13/16/8* bit
16 bit
Timer with Capture
No
Yes
External Control Pulse Counter
Yes
No
Up/Down Autoreload Timer/Counter
No
Yes
Baud Rate Generator
No
Yes
Timer Output Clock Generator
No
Yes
*8-bit timer/counter includes autoreload feature. 2x8-bit mode does not.
Each timer has a selectable time base (Table 14). Following a reset, the timers default to divide by 12 to maintain
drop-in compatibility with the 8051. If timer 2 is used as a baud rate generator or clock output, its time base is fixed
at divide by 2, regardless of the setting of its timer mode bits.
Timer 2 is a true 16-bit timer/counter that, with a 16-bit capture (RCAP2L and RCAP2H) register, is able to provide
some unique functions like up/down autoreload timer/counter and timer output-clock generation. Timer 2 (registers
TL2 and TH2) is enabled by the T2CON register. Its mode of operation is selected by the T2MOD register.
For operation details, refer to Section 11: Programmable Timers in the Ultra-High-Speed Flash Microcontroller
User’s Guide.
Timed Access
The timed-access function prevents an errant CPU from making accidental changes to certain SFR bits that are
considered vital to proper system operation. This is achieved by using software control when accessing the
following SFR control bits:
SFR
BIT
FUNCTION
WDCON.0
RWT
Reset Watchdog Timer
WDCON.1
EWT
Watchdog Reset Enable
WDCON.3
WDIF
Watchdog Interrupt Flag
WDCON.6
POR
Power-On Reset Flag
EXIF.0
BGS
Bandgap Select
ACON.5
PAGES0
Page Mode Select Bit 0
ACON.6
PAGES1
Page Mode Select Bit 1
ACON.7
PAGEE
Page Mode Enable
ROMSIZE.0
RMS0
Program Memory Size Select Bit 0
ROMSIZE.1
RMS1
Program Memory Size Select Bit 1
ROMSIZE.2
RMS2
Program Memory Size Select Bit 2
ROMSIZE.3
PRAME
Program RAM Enable
FCNTL.0
FC0
Flash Command Bit 0
FCNTL.1
FC1
Flash Command Bit 1
FCNTL.2
FC2
Flash Command Bit 2
FCNTL.3
FC3
Flash Command Bit 3
Before these bits can be altered, the processor must execute the timed-access sequence. This sequence consists
of writing an AAh to the timed access (TA, C7h) register, followed by writing a 55h to the same register within three
machine cycles. This timed sequence of steps allows any of the timed access-protected SFR bits to be altered
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DS89C440-QNL+ 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Ultra-High-Speed Flash Microcontrollers
DS89C440-XXX 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Ultra-High-Speed Flash Microcontrollers
DS89C450 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Ultra-High-Speed Flash Microcontrollers
DS89C450+ENG 制造商:Maxim Integrated Products 功能描述:MCU 8BIT CISC 64KB FLASH 5V 44TQFP - Trays