Canon BJC 50 - Color Inkjet Printer Service Manual

ll ECP MODESTROBE [Input] (Host Clk):STROBE signal handshakes with the BUSY signal (Periph Ack) to transmit data fromthe computer to the printer during the forward phase. When STROBE signal is low,it indicates that data has been sent to data bus. Reverse phase is always high.DATA 1~8 [Input]:When the host computer outputs data during the forward phase, DATA signal isinput signal. When the printer outputs data to the host computer during the reversephase, DATA signal is output signal.INIT [Input] (Reverse Req):INIT signal is set to low to perform a recovery process of the data sent from the hostcomputer during the forward phase. INIT signal responds to the low PE signal and becomeshigh. INIT signal is lowered when the forward phase idle is switched to the reverse phase.When the reverse phase is switched to forward phase, INIT signal is raised to high.AUTO FEED XT [Input] (Host Busy):During the forward phase, the AUTO FEED XT signal on data bus indicates whetherthe information is in a data or command form.Low: Command formHigh: Data formSELECT IN [Input] (1284 Active):SELECT IN signal is high at the beginning of negotiation and remains high duringthe ECP mode. This indicates that the printer is operating under bidirectional mode.After completing the ECP mode, SELECT IN signal is low.ACKNLG [Output]:The ACKNLG signal is always high during the forward phase. During the reversephase, ACKNLG signal is low to indicate data has been outputted from the hostcomputer to the data bus. ACKNLG signal responds high to the host computer'sAUTO FEED XT signal high signal.P.E. [Output] (AckReverse):PE signal is always high during the forward phase and it is always low during thereverse phase. PE signal is lowered in response to the host computer's low INITsignal to confirm the request to transfer from the forward phase to the reverse phase.SELECT [Output] (X flag):SELECT signal is always high.ERROR [Output] (Periph Req):If there is still data to be transferred in the host computer, a low ERROR signal isreleased to request reverse phase.BUSY [Output] (PeriphAck):During the forward phase, BUSY signal is low if the computer can send data. Oncethe data has been outputted BUSY signal becomes high. During the reverse phase,the form of data sent from the printer to the data bus is shown as follows:Low: Command formHigh: Data formPart 2: Product Specifications BJC-502-18