參數資料
型號: MC68HC11A8BCP2
廠商: MOTOROLA INC
元件分類: 微控制器/微處理器
英文描述: HCMOS Single-Chip Microcontroller
中文描述: 8-BIT, MROM, 2 MHz, MICROCONTROLLER, PDIP48
封裝: DIP-48
文件頁數: 47/158頁
文件大?。?/td> 776K
代理商: MC68HC11A8BCP2
MC68HC11A8
TECHNICAL DATA
SERIAL COMMUNICATIONS INTERFACE
MOTOROLA
5-3
5
Once a valid start bit is detected, the start bit, each data bit, and the stop bit are sam-
pled three times at RT intervals 8 RT, 9 RT, and 10 RT (1 RT is the position where the
bit is expected to start), as shown in
Figure 5-2
. The value of the bit is determined by
voting logic which takes the value of the majority of samples.
Figure 5-2 Sampling Technique Used on All Bits
5.5 Start Bit Detection
When the RxD input is detected low, it is tested for three more sample times (referred
to as the start edge verification samples in
Figure 5-3
). If at least two of these three
verification samples detect a logic zero, 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 zero. A valid start bit could be assumed with a set noise flag present.
If there has been a framing error without detection of a break (10 zeros for 8-bit format
or 11 zeros 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 one, and the three logic one start qualifiers (shown
in
Figure 5-3
) are forced into the sample shift register during the interval when detec-
tion of a start bit is anticipated (see
Figure 5-4
); therefore, the start bit will be accepted
no sooner than it is anticipated.
If the receiver detects that a break produced the framing error, the start bit will not be
artificially induced and the receiver must actually detect a logic one before the start bit
can be recognized. See
Figure 5-5
.
16
R
T
1
R
T
8
R
T
9
R
T
10
R
T
RxD
SCI BIT SAMPLING
PREVIOUS BIT
PRESENT BIT
SAMPLES
NEXT BIT
16
R
T
1
R
T
v
v
v
相關PDF資料
PDF描述
MC68HC11A8BMP2 HCMOS Single-Chip Microcontroller
MC68HC11A8BVP2 HCMOS Single-Chip Microcontroller
MC68HC11A1CFN2 HCMOS Single-Chip Microcontroller
MC68HCP11A1CFN2 HCMOS Single-Chip Microcontroller
MC68HCP11A1CFN3 HCMOS Single-Chip Microcontroller
相關代理商/技術參數
參數描述
MC68HC11A8BMP2 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:HCMOS Single-Chip Microcontroller
MC68HC11A8BVP2 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:HCMOS Single-Chip Microcontroller
MC68HC11A8FN 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:8-Bit Microcontrollers
MC68HC11A8FN1 制造商:Motorola Inc 功能描述:
MC68HC11A8MCFN2 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:HCMOS Single-Chip Microcontroller