Canon BJC 50 Service Manual - Page 124

Part 4: Technical Reference BJC-50 4.2.2 Control section components a) ASIC (IC6) The ASIC is comprised of the MPU section and the printer controller section. It has a built-in 16-bit CPU and the operating synchronized frequency is 23.04 MHz. The printer controller's operating synchronized frequencies are 23.04 MHz and 24.00 MHz. The MPU section and the printer controller section operate in synchronization. 1) MPU Address bus The 21-bit address bus ports is connected to an 4 M-byte flash ROM and 8 M-byte FONT ROM. The flash ROM/FONT ROM synchronizes with the read signals output by the MPU and the 23.04 MHz clock signal. The printer controller then selects the chip. Data bus Like the address bus, the 16-bit data bus port is connected to the 8 M-byte FONT ROM. Stepping motor controller The stepping motor controller outputs the carriage motor micro-step control signals and paper feed motor's double-phase exciter drive signals and single-and double-phase exciter drive signals. Interrupt controller For external interruption, the MPU has POWER button on/off switch, data reception, initial interrupt request and other signals. Each signal is inputted to each port and interrupt processing is executed. A/D converter The following analog signals are detected by the built-in A/D converter. The signals from four A/D ports are divided into two groups (A and B) with 4 signals per group. Use the external analog switch to select a group. A/D port AD0 AD1 AD2 AD3 Group A Head ID Head Temperature Head Rank Printer Internal Temperature Group B Voltage input Recharging Battery Voltage Recharge Current Battery Temperature Use the output LPC2 as the analog switch. All inputs will be connected to the A/D port of ASIC when LPC2 is set to either "0" for Group A or "1" for Group B. EEPROM write/read control The TE-CLK signal output from the ASIC is EEPROM's clock signal. The recorded data in the EEPROM is read using the TOE signals. The read-out data is output from the ASIC by the TEDIO signals and written on the EEPROM using EDO signals. I/O port The following signals are inputted to the input port: (i) signals from the POWER, RESUME and CARTRIDGE buttons and (ii) EEPROM read signals. The output signals outputs flash ROM rewrite signals and recharge LED ON/OFF signals. 4-36