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Summary of change:
'''Developer notes to evaluate http://caraca.sourceforge.net/ ''' We don't want to duplicate their docs, but evaluate how it competes with HW implemented CAN (in LPC ARM) or modbus over serial (or profibus or similar). I know some people (Johan?) examined closely, please take some notes. '''Main questions:''' * how easy it is to integrate to our firmware? if costly, we might just want to drop ARM on every network-designated board and postpone CAN support for small uC-s * interrupt latency it introduces (important if the main task of uC is ignition control) * CPU clocks from userspace (not as costly as CPU clocks spent in interrupt, but still counts) for given baudrate. This changes in function of: ** minimal: if all frames are neglected (addressed to other nodes) ** if all frames are fully processed '''CPU overhead''' * Using HW uart (right?) so: 1 interrupt / byte on AVR (no FIFO) ** I assume bytes (at least for non-neglected frames) are immediately passed up to userspace, so interrupt handler is short (right?) * CRC calculation? Costlier (regarding CPU and flash) than modbus.org (modbus over serial) RTU checksum? * other costs ? bit stuffing or similar ?
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