Geely CK Series 2007 Workshop Manual page 90

ECU microcomputer consists of microprocessor, memory, clock generator, timer, I/O interface and input
level A/D converter that are integrated in a large scale integrated circuit chip, that is SCM (Single Chip
Microcomputer).
1. Input level
The input signals from the sensor are pre-processed by the input level. The input signals are sent to protected
circuit first, sometimes through the signal converter and amplifier, and then sent to microcomputer.
The sensor signal is separated into switch type and analog type. Ignition on/off signal, camshaft position
signal, vehicle speed signal and A/C signal are switch type; Signals such as battery voltage, engine temperature,
intake temperature, airflow, intake manifold absolute pressure, throttle opening, excessive air coefficient,
knock, A/C refrigerant pressure are analog type. Analogy signal can only be processed by the digital micro-
computer after being converted into digital signal by A/D converter. Hence, data collection shall be made
first for analog signal, and the sampling shall be maintained also.
Speed and crankshaft position reference signal from the sensor is processed in a dedicated circuit to restrain
the interference pulse.
2. Microcomputer
The microcomputer of the engine electronic control unit is integrated in a single chip microcomputer, consist-
ing of the following:
(1) Microprocessor, microprocessor is also called as central processing unit (CPU), consisting of the following
three parts:
Arithmetic logic unit.
Register group.
Controller.
(2) System assembly, The data transferred among the internal sections of the single chip microcomputer
(SCM) is performed on the internal bus, while that between the SCM and other components is performed
on the external bus. The external bus is also called system bus. It is separated into data bus, address bus
and control bus.
(3) Memory, the memory is designed to store the binary data. The primary components of the memory are:
Memory.
Data register.
Address register, address decoder.
a. Memory controller
(4) A/D converter
(5) I/O interface.
(6) Clock generator.
(7) Timer
(8) CAPCOM unit.
(9) Watchdog timer.
(10) Interrupt system.
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