Canon BJC-55 Service Bulletin

Also see for BJC-55 Series: Service manual User manual Start here User manual Specification

2) Printer controller sectionThe printer controller contains the parallel interface controller, print headcontroller, scanner head controller, CR motor controller, paper feed motorcontroller, buffer controller, DRAM controller, recharge controller, etc. It operate insynchronization with an external 23.04 MHz external clock input.Interface controllerThe interface controller receives from the computer, 8-bit parallel data which issynchronized with the data strobe pulse (STROBE) through the BUSY/ACKNLGhandshake. It also controls IrDA and ASK interface signals.The data received through the interface is stored in the DRAM's receive buffer andanalyzed by the ASIC.DRAM controllerThe DRAM controller is a DRAM-specific bus separate from the MPU section bus.It controls the 4 M bit DRAM's 10-bit address/16-bit data bus and also executesread/write control, RAS/CAS control, and refresh control.Buffer controllerThe buffer controller automatically writes the received data to the receive buffer onthe DRAM, manages the receive buffer's remaining capacity, automatically readsthe print buffer, and clears the data after it is read.Print head controllerThe print head controller converts the print data read from the DRAM's print bufferfrom parallel to serial and sends the serial data to the print head. For large andsmall dot printing, the print head controller outputs 4 heat-enable signals (HENBA,HENBB, HENBC and HENBD). Each enable signal can be output independently.Scanner cartridge controllerThe scanner cartridge controller tries to operate the printer as a scanner once itreceives a scanner activation message from the host computer. In the scannermode, data cannot be removed from the receiver buffer.Recharge controllerThe recharge controller controls the battery recharge controller IC which is drivenby the recharging electrical current, temperature and voltage values transmittedthrough the A/D port.I/O portThe input port contains the home position sensor, the delivery sensor, the paperend sensor, and a data input signal for the optional ASF unit. The output portcontrols the beeper, ERROR LED on/off signals, battery recharge on/off signals,battery power output on/off signals, A/D port analog switch signal, CR excitermotor, drive signals and a data output signal for the optional ASF unit.b) Flash ROM/FONT ROM (IC9/IC10)This printer has a flash ROM as the control board lacked space for an EPROM. The4 M-byte flash ROM contains printer control programs and program-rewrite loadingprograms. The 8 M-byte FONT ROM contains the bitmap font data for printercontrol.4-37BJC-50Part 4: Technical Reference