参数资料
型号: MC9S08AW60MPUE
厂商: FREESCALE SEMICONDUCTOR INC
元件分类: 微控制器/微处理器
英文描述: 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PQFP64
封装: 10 X 10 MM, 1.40 MM HEIGHT, 0.50 MM PITCH, LEAD FREE, PLASTIC, MS-026BCD, LQFP-64
文件页数: 107/324页
文件大小: 3579K
代理商: MC9S08AW60MPUE
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Chapter 11 Serial Communications Interface (S08SCIV2)
MC9S08AW60 Data Sheet, Rev 2
Freescale Semiconductor
195
to Section 11.3.5.1, “8- and 9-Bit Data Modes.” For the remainder of this discussion, we assume the SCI
is congured for normal 8-bit data mode.
After receiving the stop bit into the receive shifter, and provided the receive data register is not already full,
the data character is transferred to the receive data register and the receive data register full (RDRF) status
ag is set. If RDRF was already set indicating the receive data register (buffer) was already full, the overrun
(OR) status ag is set and the new data is lost. Because the SCI receiver is double-buffered, the program
has one full character time after RDRF is set before the data in the receive data buffer must be read to avoid
a receiver overrun.
When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive
data register by reading SCIxD. The RDRF ag is cleared automatically by a 2-step sequence which is
normally satised in the course of the user’s program that handles receive data. Refer to Section 11.3.4,
“Interrupts and Status Flags” for more details about ag clearing.
11.3.3.1
Data Sampling Technique
The SCI receiver uses a 16
× baud rate clock for sampling. The receiver starts by taking logic level samples
at 16 times the baud rate to search for a falling edge on the RxD serial data input pin. A falling edge is
dened as a logic 0 sample after three consecutive logic 1 samples. The 16
× baud rate clock is used to
divide the bit time into 16 segments labeled RT1 through RT16. When a falling edge is located, three more
samples are taken at RT3, RT5, and RT7 to make sure this was a real start bit and not merely noise. If at
least two of these three samples are 0, the receiver assumes it is synchronized to a receive character.
The receiver then samples each bit time, including the start and stop bits, at RT8, RT9, and RT10 to
determine the logic level for that bit. The logic level is interpreted to be that of the majority of the samples
taken during the bit time. In the case of the start bit, the bit is assumed to be 0 if at least two of the samples
at RT3, RT5, and RT7 are 0 even if one or all of the samples taken at RT8, RT9, and RT10 are 1s. If any
sample in any bit time (including the start and stop bits) in a character frame fails to agree with the logic
level for that bit, the noise ag (NF) will be set when the received character is transferred to the receive
data buffer.
The falling edge detection logic continuously looks for falling edges, and if an edge is detected, the sample
clock is resynchronized to bit times. This improves the reliability of the receiver in the presence of noise
or mismatched baud rates. It does not improve worst case analysis because some characters do not have
any extra falling edges anywhere in the character frame.
In the case of a framing error, provided the received character was not a break character, the sampling logic
that searches for a falling edge is lled with three logic 1 samples so that a new start bit can be detected
almost immediately.
In the case of a framing error, the receiver is inhibited from receiving any new characters until the framing
error ag is cleared. The receive shift register continues to function, but a complete character cannot
transfer to the receive data buffer if FE is still set.
11.3.3.2
Receiver Wakeup Operation
Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a
message that is intended for a different SCI receiver. In such a system, all receivers evaluate the rst
相关PDF资料
PDF描述
MC9S08AW60CFGE 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PQFP44
MC9S08AW16MFDE 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, QCC48
MC9S08AW48MFUE 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PQFP64
MC9S08AW48CFUER 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, PQFP64
MC9S08AW60MFDE 8-BIT, FLASH, 40 MHz, MICROCONTROLLER, QCC48
相关代理商/技术参数
参数描述
MC9S08AW60VFGE 功能描述:8位微控制器 -MCU 8B 60K FLASH 4K RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
MC9S08AW8A 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:8-Bit HCS08 Central Processor Unit (CPU)
MC9S08DE32 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC9S08DE60 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Microcontrollers
MC9S08DE60AD 制造商:FREESCALE 制造商全称:Freescale Semiconductor, Inc 功能描述:Addendum to MC9S08DE60 Series Data Sheet