參數(shù)資料
型號(hào): MC68HC05P3
廠商: Motorola, Inc.
元件分類: DC/DC變換器
英文描述: RS3-S_D(Z) Series - Econoline Regulated DC-DC Converters; Input Voltage (Vdc): 12V; Output Voltage (Vdc): 05V; Power: 3W; 2:1 and 3:1 Wide Input Voltage Ranges; 1kVDC, 2kVDC & 3kVDC Isolation; UL94V-0 Package Material; Continuous Short Circuit Protection; Low Ripple and Noise; Remote On/Off Control; Efficiency to 83%
中文描述: 微機(jī)單位的16位可編程定時(shí)器
文件頁數(shù): 42/96頁
文件大?。?/td> 3045K
代理商: MC68HC05P3
MC68HC05SR3
Freescale
6-1
TIMER
6
TIMER
This section describes the operation of the 8-bit count-down timer in the MC68HC05SR3.
6.1
Timer Overview
The MC68HC05SR3 timer block diagram is shown in Figure 6-1. The timer contains a single 8-bit
software programmable count-down counter with a 7-bit software selectable prescaler. The
counter may be preset under software control and decrements towards zero. When the counter
decrements to zero, the timer interrupt flag (TIF bit in Timer Control Register, TCR) is set. Once
timer interrupt flag is set, an interrupt is generated to the CPU only if the TIM bit in the TCR and
I-bit in the CCR are cleared. When a interrupt is recognized, after completion of the current
instruction, the processor proceeds to store the appropriate registers on the stack and then
fetches the timer interrupt vector from locations $1FF6 and $1FF7.
The counter continues to count after it reaches zero, allowing the software to determine the
number of internal or external clocks since the timer interrupt flag was set. The counter may be
read at any time by the processor without disturbing the count. The contents of the counter
become stable prior to the read portion of a cycle and do not change during the read. The timer
interrupt flag remains set until cleared by the software. If a write occurs before the timer interrupt
is served, the interrupt is lost. The timer interrupt flag may also be used as a scanned status bit in
a non-interrupt mode of operation.
The prescaler is a 7-bit divider which is used to extend the maximum length of the timer. Bit 0, 1,
2 (PR0, PR1, PR2) of TCR are programmed to choose the appropriate prescaler output which is
used as the 8-bit counter clock input. The processor cannot write into or read from the prescaler;
however, its contents can be cleared to all zeros by writing to the PRER bit in the TCR. This will
allow for truncation-free counting.
The input clock for the timer sub-system is selectable from internal, external, or a combination of
internal and external sources. The TCEX and TINE bits in the Timer Control Register selects the
timer input clock.
TPG
45
05SR3.Book Page 1 Thursday, August 4, 2005 1:08 PM
相關(guān)PDF資料
PDF描述
MC78L05 5.0 AMP POSITIVE VOLTAGE REGULATOR
MC100EP16D Differential Receiver
MC33984 Dual Intelligent High-Current Self-Protected Silicon High-Side Switch (4.0 mз)
MC33689 Single Output LDO, 400mA, Fixed(2.85V), Low Noise, Fast Transient Response 8-MSOP -40 to 85
MC33689DWB Single Output LDO, 400mA, Fixed(2.85V), Low Noise, Fast Transient Response 8-MSOP -40 to 85
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC68HC05P4 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNIT
MC68HC05P4A 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC68HC05P4DW 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNIT
MC68HC05P4P 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNIT
MC68HC05P6 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNIT