參數(shù)資料
型號： MC68HC705C9ACP
廠商： MOTOROLA INC
元件分類： 微控制器/微處理器
英文描述： Microcontrollers
中文描述： 8-BIT, OTPROM, 2.1 MHz, MICROCONTROLLER, PDIP40
封裝： PLASTIC, DIP-40
文件頁數(shù)： 93/160頁
文件大?。?/td> 2076K
代理商： MC68HC705C9ACP
Serial Communications Interface (SCI)
Start Bit Detection
MC68HC705C9A — Rev. 4.0
Advance Information
MOTOROLA
Serial Communications Interface (SCI)
For More Information On This Product,
Go to: www.freescale.com
93
9.12 Start Bit Detection
When the input (idle) line is detected low, it is tested for three more
sample times (referred to as the start edge verification samples in
Figure 9-4
). If at least two of these three verification samples detect a
logic 0, a valid start bit has been detected; otherwise, the line is assumed
to be idle. A noise flag is set if all three verification samples do not detect
a logic 0. Thus, a valid start bit could be assumed with a set noise flag
present.
If a framing error has occurred without detection of a break (10 0s for
8-bit format or 11 0s for 9-bit format), the circuit continues to operate as
if there actually was a stop bit, and the start edge will be placed
artificially. The last bit received in the data shift register is inverted to a
logic 1, and the three logic 1 start qualifiers (shown in
Figure 9-4
) are
forced into the sample shift register during the interval when detection of
a start bit is anticipated (see
Figure 9-6
); therefore, the start bit will be
accepted no sooner than it is anticipated.
If the receiver detects that a break (RDRF = 1, FE = 1, receiver data
register = $003B) produced the framing error, the start bit will not be
artificially induced and the receiver must actually detect a logic 1 before
the start bit can be recognized (see
Figure 9-7
).
Figure 9-6. SCI Artificial Start Following a Frame Error
DATA
EXPECTED STOP
DATA SAMPLES
a) Case 1: Receive line low during artificial edge
ARTIFICIAL EDGE
START BIT
DATA
RDI
DATA
EXPECTED STOP
DATA SAMPLES
START EDGE
START BIT
DATA
RDI
b) Case 2: Receive line high during expected start edge
F
Freescale Semiconductor, Inc.
n
.
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參數(shù)描述
MC68HC705C9ACPE 制造商:Freescale Semiconductor 功能描述:
MC68HC705C9AFNE 功能描述:8位微控制器 -MCU 8B MCU 352 BYTES RAM 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(fēng)格:SMD/SMT
MC68HC705C9AVFNE 功能描述:8位微控制器 -MCU 8B MCU 352 BYTES RAM 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(fēng)格:SMD/SMT
MC68HC705E6CDW 制造商:Motorola Inc 功能描述: 制造商:MOTOROLA 功能描述:
MC68HC705G1B 制造商:Rochester Electronics LLC 功能描述:- Bulk
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