參數(shù)資料
型號: MC68HC05BS8FB
廠商: MOTOROLA INC
元件分類: 微控制器/微處理器
英文描述: 8-BIT, MROM, 2.2 MHz, MICROCONTROLLER, PQFP44
封裝: QFP-44
文件頁數(shù): 100/128頁
文件大小: 752K
代理商: MC68HC05BS8FB
MC68HC05BS8
MOTOROLA
8-13
M-BUS SERIAL INTERFACE
8
LAMAR
BSET
3,MCR
; LAST SECOND, DISABLE ACK
; TRANSMITTING
BRA
NXMAR
ENMASR BCLR
5,MCR
; LAST ONE, GENERATE 'STOP'
; SIGNAL
NXMAR
LDA
MDR
; READ DATA AND STORE
STA
RXBUF
RTI
8.4.5
Generation of a Repeated START Signal
At the end of data transfer, if the master still wants to communicate on the bus, it can generate
another START signal followed by another slave address without rst generating a STOP signal.
A program example is as shown.
RESTART
BCLR
5,MCR
; ANOTHER START (RESTART) IS
BSET
5,MCR
; GENERATED BY THESE TWO
; CONSECUTIVE INSTRUCTIONS
LDA
#CALLING
; GET THE CALLING ADDRESS
STA
MDR
; TRANSMIT THE CALLING
; ADDRESS
8.4.6
Slave Mode
In the slave service routine, the master addressed as slave bit (MAAS) should be tested to check
if a calling of its own address has been received (Figure 8-4). If MAAS is set, software should set
the transmit/receive mode select bit (MTX bit of MCR) according to the R/W command bit (SRW).
Writing to the MCR clears the MAAS automatically. A data transfer may then be initiated by writing
to MDR or a dummy read from MDR.
In the slave transmit routine, the received acknowledge bit (RXAK) must be tested before
transmitting the next byte of data. RXAK, if set indicates the end of data signal from the master
receiver, the slave transmitter must then switch from transmit mode to receive mode by software
and a dummy read must follow to release the SCL line so that the master can generate a STOP
signal.
8.4.7
Arbitration Lost
If more than one master want to acquire the bus simultaneously, only one master can win and the
others will lose arbitration. The losing device immediately switches to slave receive mode by
M-Bus hardware. Its data output to the SDA line is stopped, but internal transmit clock still runs
until the end of the data byte transmission. An interrupt occurs when this dummy byte transmission
TPG
71
相關(guān)PDF資料
PDF描述
MC68HC705F4P 8-BIT, OTPROM, 1.789 MHz, MICROCONTROLLER, PDIP28
MC68HC705F4FB 8-BIT, OTPROM, 1.789 MHz, MICROCONTROLLER, PQFP44
MC68HC05F4FB 8-BIT, MROM, 1.789 MHz, MICROCONTROLLER, PQFP44
MC68HC05F4CDW 8-BIT, MROM, 1.789 MHz, MICROCONTROLLER, PDSO28
MC68HC705G4 8-BIT, OTPROM, 1 MHz, MICROCONTROLLER, PQFP80
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC68HC05C0CP 制造商:Motorola Inc 功能描述:
MC68HC05C12 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNITS
MC68HC05C12B 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNITS
MC68HC05C12CP 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNITS
MC68HC05C12P 制造商:FREESCALE 制造商全稱:Freescale Semiconductor, Inc 功能描述:HCMOS MICROCONTROLLER UNITS