Main Signal Processor
75. Diagram 14 shows the Main Signal Processor. Apart from the software, it consists of the following main hardware components:
CPU - The CPU is used to execute all the high level arithmetic logic functions that are required for electronic control and regulation.
CPUDB - CPU Data Bus. This is the data bus that the Data Link Controller (DLC) uses to move data between itself and the CPU.
CPU Memory - This memory is used in the standard way in order to control the function of the CPU and store data.
Data Link Controller - When the CPU wants or needs to communicate with the outside world, it initiates a request to the Data Link Controller. That request will usually be a request to pick up some data that it has calculated and placed at a specified place in it's own memory.
- When the Data Link Controller has received data from the other components, it will initialize a request on the CPU and at the give time move that data to the designated destination in CPU Memory.
DLCDB - Data Link Controller Data Bus. This is the data bus along which data is moved, when it is moved from a source to a new destination. It is not necessarily the data bus that carries program code. The data bus along which program code is usually moved, is not shown in the drawing. The advantage of using a fourth data bus for program code is that:
I. Read Only Memory (ROM) is used for the program code and it can not be modified during program execution.
II. The maximum voltage that a ROM or similar device can work with is close to the programming voltage and that means that the program will have an higher survival rate than the program data.
III. The speed loss that occurs due to error checking on the other data busses of the Data Link Controller (DLC) will be compensated by the fact that data does not share the same bus with program code.
IV. The use of 4 data buses in the Data Link Controller (DLC) does not prevent the use of only one address sequencer.
DLC Memory - This memory is used as an intermediate storage for data that the Data Link Controller will receive from a source and later move to CPU Memory or data that the Data Link Controller will first move from CPU Memory to it and then from there to a destination.
SLDB - Serial Data Bus. This is the data that the Data Link Controller (DLC) uses to move data between itself and the outside world. The serial connections are classified here as being part of the outside world.
GPDI - General Purpose Digital Interface. It is the Signal Processor's direct link to the analog outside world.
I/O - Binary and Tri-State switches.
76. The Data Link Controllers are used in the circuits to provide data pipe lines between other electronic components, while being able to detect internal errors within themselves. That means that the Data Link Controller that are used as repeaters are able to detect on which side of the connection an error has occurred.
77. The main thing about the Data Link Controller, apart from it's multi-function capabilities, is that it can check the data that it moves from it's Memory to see if the Memory cell is defect, before it passes that data on to other components in the circuit. For that (transmission) purpose, error detection codes are added to data words.
The basic structure of the main signal processor for safe electric vehicles