参数资料
型号: MT80C51-12R
厂商: TEMIC SEMICONDUCTORS
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 12 MHz, MICROCONTROLLER, PQFP44
文件页数: 125/170页
文件大小: 4133K
代理商: MT80C51-12R
58
ATtiny4/5/9/10 [DATASHEET]
8127F–AVR–02/2013
clock cycles. Note that the input of the noise canceler and edge detector is always enabled unless the Timer/Coun-
ter is set in a Waveform Generation mode that uses ICR0 to define TOP.
An Input Capture can be triggered by software by controlling the port of the ICP0 pin.
11.5.2
Noise Canceler
The noise canceler improves noise immunity by using a simple digital filtering scheme. The noise canceler input is
monitored over four samples, and all four must be equal for changing the output that in turn is used by the edge
detector.
The noise canceler is enabled by setting the Input Capture Noise Canceler (ICNC0) bit in Timer/Counter Control
Register B (TCCR0B). When enabled the noise canceler introduces additional four system clock cycles of delay
from a change applied to the input, to the update of the ICR0 Register. The noise canceler uses the system clock
and is therefore not affected by the prescaler.
11.5.3
Using the Input Capture Unit
The main challenge when using the Input Capture unit is to assign enough processor capacity for handling the
incoming events. The time between two events is critical. If the processor has not read the captured value in the
ICR0 Register before the next event occurs, the ICR0 will be overwritten with a new value. In this case the result of
the capture will be incorrect.
When using the Input Capture interrupt, the ICR0 Register should be read as early in the interrupt handler routine
as possible. Even though the Input Capture interrupt has relatively high priority, the maximum interrupt response
time is dependent on the maximum number of clock cycles it takes to handle any of the other interrupt requests.
Using the Input Capture unit in any mode of operation when the TOP value (resolution) is actively changed during
operation, is not recommended.
Measurement of an external signal’s duty cycle requires that the trigger edge is changed after each capture.
Changing the edge sensing must be done as early as possible after the ICR0 Register has been read. After a
change of the edge, the Input Capture Flag (ICF0) must be cleared by software (writing a logical one to the I/O bit
location). For measuring frequency only, the clearing of the ICF0 flag is not required (if an interrupt handler is
used).
11.6
Output Compare Units
The 16-bit comparator continuously compares TCNT0 with the Output Compare Register (OCR0x). If TCNT equals
OCR0x the comparator signals a match. A match will set the Output Compare Flag (OCF0x) at the next timer clock
cycle. If enabled (OCIE0x = 1), the Output Compare Flag generates an Output Compare interrupt. The OCF0x flag
is automatically cleared when the interrupt is executed. Alternatively the OCF0x flag can be cleared by software by
writing a logical one to its I/O bit location. The Waveform Generator uses the match signal to generate an output
according to operating mode set by the Waveform Generation mode (WGM03:0) bits and Compare Output mode
(COM0x1:0) bits. The TOP and BOTTOM signals are used by the Waveform Generator for handling the special
cases of the extreme values in some modes of operation (“Modes of Operation” on page 61).
A special feature of Output Compare unit A allows it to define the Timer/Counter TOP value (i.e., counter resolu-
tion). In addition to the counter resolution, the TOP value defines the period time for waveforms generated by the
Waveform Generator.
Figure 11-6 on page 59 shows a block diagram of the Output Compare unit. The small “n” in the register and bit
names indicates the device number (n = 0 for Timer/Counter 0), and the “x” indicates Output Compare unit (A/B).
The elements of the block diagram that are not directly a part of the Output Compare unit are gray shaded.
相关PDF资料
PDF描述
MF280C51C-25D 8-BIT, MROM, 25 MHz, MICROCONTROLLER, PQFP44
MV80C51-30D 8-BIT, MROM, 30 MHz, MICROCONTROLLER, PQFP44
MF180C31-36R 8-BIT, 36 MHz, MICROCONTROLLER, PQFP44
MF280C51-20D 8-BIT, MROM, 20 MHz, MICROCONTROLLER, PQFP44
MF180C51-25D 8-BIT, MROM, 25 MHz, MICROCONTROLLER, PQFP44
相关代理商/技术参数
参数描述
MT80C51BH 制造商:ROCHESTER 制造商全称:ROCHESTER 功能描述:CMOS SINGLE - CHIP 8-BIT MICROCOMPUTER 64K program Memory Space
MT80C51FB 制造商:Rochester Electronics LLC 功能描述:- Bulk
MT80C51FB/B 制造商:Intel 功能描述:
MT80GB 制造商:Datak Corporation 功能描述:
MT80JSF1G72NDY-1G1F1A2 制造商:Micron Technology Inc 功能描述:8GB 1GX72 DDR3 SDRAM MODULE PBF DIMM 1.5V REGISTERED - Trays