Canon S600 Service Manual page 74

Part 3: Technical Reference
7. Print head control
Serial print data is sent to the print head.
The transfer clock is 6 MHz. Since data latch occurs at the clock's start-up and
shutdown, the data transfer speed is faster.
Also, the print head heater's heating is executed with a single pulse or double
pulse. In the case of a double pulse, the first pulse is a press pulse. The pulse
following it becomes the main pulse.
The print head's temperature is estimated with the dot count. Based on the
estimated temperature, suitable heating is executed with the voltage value.
8. Motor control
The encoder signals input from the two DC motors are processed, and a signal for
the 1-2-phase driving of the auto sheet feeder motor is generated.
b) MPU (IC203)
The MPU contains a 32-bit CPU, 16 KB work RAM, 21-bit address bus port, 16-bit
data bus port, interrupt controller, A/D converter, I/O port, and other built-in
components. With the chip select signal, the MPU selects the control ROM, printer
controller, and DRAM.
Built-in CPU
The 32-bit CPU operates in synchronization with a 48 MHz external clock input.
Address bus/Data bus
This operates in synchronization with a 20 MHz external clock input. An external
RAM (16 Mbit) is accessed via the 16-bit data bus.
Interrupt controller
The MPU receives external interrupts from the POWER button's ON/OFF and I/F.
A/D converter
The following analog signals are detected after they pass through the built-in A/D
converter.
Resume key input
EEPROM data I/O
EEPROM chip select output
Door sensor input
CSB power input
Sensor (purge, paper end, sheet feeder) inputs
LED (ERROR/POWER) outputs
I/F (Centronics/CSB) pull-up control I/O
Print head power control (ON/OFF)
(VDD/VH)
Ink sensor power control (ON/OFF)
Purge motor control (4 ports, A/B/A/B phase)
I/O port
The I/O port executes the following control operations.
c) DRAM (IC103)
The 16 Mbit DRAM is controlled by the printer controller and used as a receiving
buffer, download buffer, print buffer, and working area.
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S600