Project Analog - March 2008 - (Page 18)

lower priority node(s) will then switch to receiver mode and wait for the next bus idle to attempt transmission again. The winning transmitter will continue to send its message as if nothing happened. Response time to collision resolution is faster because the correction occurs at the beginning of the transmission during arbitration of a message and the high priority message is not destroyed. CANbus communication is achieved using message frames. The three types of frames are data, remote and error. Each frame has internal fields that define the type of frame that is being sent and then provides the pertinent information. For instance, a data frame is constructed with 6 fields: arbitration, control, data, CRC (Cyclic Redundancy Check), acknowledge and end-offrame. During transmission, the arbitration field is used by every node on the network to identify and/or resolve collisions. The arbitration field is also used to identify the message type and destination. The control frame defines the data frame length. The data frame contains data and has the specified number of bytes per the control frame. The CRC frame is used to check for data errors. And finally, every transmission requires an acknowledge frame from all of the receivers on the CAN network. In the CAN network multi-master environment, nodes can be added or removed without significant 18 · ProjeCt ANALog · mAr 08 Contents Viewpoint Wireless Communication Using IrDA® Wireless Design Choices Advanced Communication Solutions for Lighting Analog news fig 1 for multi-tasK nEtworKs, a cEntralizEd nEtworK is usually usEd for EthErnEt systEms. if a nodE is addEd to this systEm, thE systEm mcu could rEquirE significant modifications. with can nEtworKs, thE distributEd nEtworK is imPlEmEntEd. a nodE can Easily bE addEd or taKEn out of thE systEm with minimal firmwarE changEs. Microchip analog page Interface products overview Sample center microchipDIRECT Reference designs/ app notes Technical training fig 2 this is an ExamPlE of a singlE nodE for a can nEtworK. all of thE ElEmEnts for aPProPriatE communication on thE nEtworK arE imPlEmEntEd through thE can drivEr (mcP2551), can controllEr (mcP2515) and thE microcontrollEr. http://www.microchip.com http://www.microchip.com/analog http://www.microchip.com/analog http://www.microchip.com/interface http://www.microchip.com/interface http://sample.microchip.com/Default.aspx?testCookies=true http://www.microchipdirect.com/catalogselection.aspx?returnURL=default.aspx http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1469&filter1=function&redirects=appnotes http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1423

Table of Contents Feed for the Digital Edition of Project Analog - March 2008

Project Analog - March 2008 Contents Viewpoint About Project Analog Sponsor Wireless Communication Using the IrDA® Standard Protocol Wireless Design Choices Advanced Communication Solutions for Lighting Putting 10-GbE PHY Options Into Perspective Ease Into the Flexible CANbus Network Technology and Drivers for Mobile WiMAX Analog News—Analog News from Multiple Sources Enter to Win an iPhone Contact Project Analog Sponsor Treelink Microchip Advanced Parts Selector (MAPS)

Project Analog - March 2008

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