參數(shù)資料
型號(hào)： MC68331CPV20B1
廠商： MOTOROLA INC
元件分類： 微控制器/微處理器
英文描述： 32-BIT, 20 MHz, MICROCONTROLLER, PQFP144
封裝： 20 X 20 MM, 1.40 MM HEIGHT, 0.50 MM PITCH, PLASTIC, LQFP-144
文件頁數(shù)： 62/90頁
文件大?。?/td> 481K
代理商： MC68331CPV20B1
MC68331
MOTOROLA
MC68331TS/D
65
5.5.1 SCI Pins
There are two unidirectional pins associated with the SCI. The SCI controls the transmit data (TXD) pin
when enabled, whereas the receive data (RXD) pin remains a dedicated input pin to the SCI. TXD is
available as a general-purpose I/O pin when the SCI transmitter is disabled. When used for I/O, TXD
can be configured either as input or output, as determined by QSM register DDRQS.
The following table shows SCI pins and their functions.
5.5.2 SCI Registers
The SCI programming model includes QSM global and pin control registers, and four SCI registers.
There are two SCI control registers, one status register, and one data register. All registers can be read
or written at any time by the CPU.
Changing the value of SCI control bits during a transfer operation may disrupt operation. Before chang-
ing register values, allow the transmitter to complete the current transfer, then disable the receiver and
transmitter. Status flags in the SCSR may be cleared at any time.
SCCR0 contains a baud rate selection parameter. Baud rate must be set before the SCI is enabled. The
CPU can read and write this register at any time.
Bits [15:13] — Not Implemented
SCBR — Baud Rate
SCI baud rate is programmed by writing a 13-bit value to BR. The baud rate is derived from the MCU
system clock by a modulus counter.
The SCI receiver operates asynchronously. An internal clock is necessary to synchronize with an in-
coming data stream. The SCI baud rate generator produces a receiver sampling clock with a frequency
16 times that of the expected baud rate of the incoming data. The SCI determines the position of bit
boundaries from transitions within the received waveform, and adjusts sampling points to the proper po-
sitions within the bit period. Receiver sampling rate is always 16 times the frequency of the SCI baud
rate, which is calculated as follows:
SCI Baud Rate = System Clock/(32SCBR)
or
SCBR = System Clock(32SCK)(Baud Rate Desired)
where SCBR is in the range {1, 2, 3, ..., 8191}
Writing a value of zero to SCBR disables the baud rate generator.
The following table lists the SCBR settings for standard and maximum baud rates using 16.78-MHz and
20.97-MHz system clocks.
Pin Names
Mnemonics
Mode
Function
Receive Data
RXD
Receiver Disabled
Receiver Enabled
Not Used
Serial Data Input to SCI
Transmit Data
TXD
Transmitter Disabled
Transmitter Enabled
General-Purpose I/O
Serial Data Output from SCI
SCCR0 — SCI Control Register 0
$YFFC08
15
14
13
12
0
SCBR
RESET:
0
1
0
相關(guān)PDF資料
PDF描述
MC68331CFC25B1 32-BIT, 25 MHz, MICROCONTROLLER, PQFP132
MC68331CPV16B1 32-BIT, 16 MHz, MICROCONTROLLER, PQFP144
MC68331CPV20 32-BIT, 20.97 MHz, MICROCONTROLLER, PQFP144
MC68331CFC25 32-BIT, MICROCONTROLLER, PQFP132
MC68331MFC16 32-BIT, 16.78 MHz, MICROCONTROLLER, PQFP132
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC68331CPV25 制造商:Rochester Electronics LLC 功能描述:32BIT MCU,GPT,SIM,QSM - Bulk
MC68331LPV20 制造商:Motorola Inc 功能描述:
MC68331MEH16 功能描述:32位微控制器 - MCU 32B MCU GPT SIM QSM RoHS:否 制造商:Texas Instruments 核心:C28x 處理器系列:TMS320F28x 數(shù)據(jù)總線寬度:32 bit 最大時(shí)鐘頻率:90 MHz 程序存儲(chǔ)器大小:64 KB 數(shù)據(jù) RAM 大小:26 KB 片上 ADC:Yes 工作電源電壓:2.97 V to 3.63 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:LQFP-80 安裝風(fēng)格:SMD/SMT
MC68331MFC16 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:User’s Manual
MC68331MFC20 制造商:MOTOROLA 制造商全稱:Motorola, Inc 功能描述:User’s Manual
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