Canon BJC 6000 - Color Inkjet Printer Service Manual

2.1.3 ECP modeThe ECP mode allows data to be transferred bi-directionally between the printer andhost computer. This mode also allows 2 byte data transfer to provide faster datatransmission and reception. It is for this reason that ECP mode is suitable fortransferring large amounts of data.In response to the fall of the ReverseRequest signal, the direction of the data busswitches from forward data transfer mode to reverse data transfer mode. The forwarddata transfer mode allows data to be transferred from the host computer to theprinter, whereas the reverse data transfer mode allows data to be transferred from theprinter to the host computer.(1) The host computer causes AckReverse to go low to request reverse data transfer(data transfer from printer to host computer).(2) After confirming AckReverse is low, the printer causes AckReverse to go low toindicate that that reverse transfer is possible.(3) The printer sends 1 byte of data out on the data lines and causes PeriphAck to gohigh to tell that this data is not command but data. The printer then causesPeriphClk to go low to tell that this data is valid.(4) After confirming the signal in (3) is received, the host computer causes HostAck togo high.(5) The printer causes AckReverse to go high to have the data recorded in the hostcomputer.(6) The host computer causes HostAck to go high to get ready for the next one byte ofdata.(7) The printer repeats the process above to send the next one byte of data.Part 4: Technical Reference BJC-60004-12Data (1~8)PeriphClkHost AckReverseRequestPeriphAckAckReverseByte0 Byte1Data CmdReverse transfer phaseFigure 4-11 Interface Timing (ECP mode, reverse transfer)