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'''Developer corner: find a good way for networking the AVR (mega88) boards''' This is rather hardware related. VemsFrontier/Networking is about software/logical issues. While the big ARM guys ( VemsFrontier/ArmEfi and IonSense ) will work nice with CAN, CAN is not feasible for ATMEGA88. ATMEGA88 has an UART (ATMEGA128 also, except it has 2): * FBUS point-2-point for very short distance * RS232 point-2-point for short distance * RS485 bus for upto 32 nodes network. The only cost efficient solution that allows several small boards (displays, dongles, ECMs) to communicate without a central HUB. While FBUS requires no transceivers, the RS232 and RS485 transceivers are the same cost (very cheap) and availability. '''Neither of the above can be used to talk to most notebooks directly: since majority of notebooks have neither of these ports, only USB'''. Fortunately, [http://zone.ni.com/devzone/conceptd.nsf/webmain/F9F58CBF78A3D1ED86256C06007AF286?opendocument&node=dz00000_us bridging ]either of these to USB is simple and cheap. It is normally just a "cable" with some circuitry inside. RS232 and FBUS not only needs bridging to notebook, but also needs a HUB when more than 2 nodes are used. [http://www.rs485.com/pfaq.html converters] * symmetric drive for twisted pair preferred ** [http://focus.ti.com/docs/prod/folders/print/sn65176b.html SN65176B] makes symmetric (shielded pair) serial bus possible apparently same as '''ST485A''' ** ST490A or other driver ** you can experiment with v3 midOPA if you have no other choice * physical ring * physical bus: ** with collision detection ** or sg. like a token-ring ** 1 master + N slave (good enough) * physical star: a board with many serial connections The '''RS-485''' is basically an update of the RS-422 specified for multipoint buses to be constructed. This standard meets and improves all the requirements of the RS-422 allowing, in addition, up to 32 drivers and 32 receivers can be connected to a single bus. [http://www.st.com/stonline/prodpres/standard/interfc/rs42285.htm ST] site. TI has many cost efficient transceivers. Have you thought about LIN protocol implementation? Cheap transceiver hooks to RS-232 and has voltage regulator on board. [http://ww1.microchip.com/downloads/en/DeviceDoc/21730d.pdf]Click here
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