JPS6388666A - Bus arbitration controller - Google Patents

Abstract

PURPOSE:To evade competition for the use of bus by providing a microprocessor which does not incorporates a function to arbitrate the right to use bus and a direct memory access (DMA) controller with which the right to use bus is acquired/abandoned through a hand shake system of bus-use request signal and bus-use permission signal. CONSTITUTION:In case the microcomputer 1 that does not incorporate a bus arbitration function uses the bus, preliminarily to it, a bus-use request signal outputted from a DMA controller 2 is confirmed, and in case the use of bus is requested, the bus-use permission signal is supplied to the DMA controller 2 and thus the bus is released for the DMA controller 2. On the other hand, if the use of bus is not requested, a signal to permit the microcomputer 1 to use continuously the bus is outputted, and the microcomputer 1 uses the bus. In such a way, the competition for the bus-use between a microcomputer not having the bus arbitration function and a DMA controller can be evaded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to bus usage conflicts that occur between a microcomputer and a direct memory access control device (hereinafter referred to as DMA control device) arranged on a common bus. The present invention relates to a bus arbitration control device that avoids. , Prior Art In a conventional system in which a microcomputer and a DMA control device are placed on a common bus, a bus use permission signal is issued in response to a bus use request signal issued by the DMA control device.
A microcomputer is often used that has a built-in bus arbitration function that hands over the right to use the bus to a control device.

Problems to be Solved by the Invention When a DMA control device is installed in a system that acquires and relinquishes the right to use the bus using a handshake method of a bus use request signal and a bus use permission signal, it is necessary to A microcomputer must be selected that has built-in functionality that is open to the bus 7i DMA controller. When applied to a system equipped with this DMA control device, the S microcomputer was limited, making it difficult to design a flexible system.

The present invention has been made to address this point, and is a bus arbitration side part that has a simple configuration and avoids bus contention that occurs between a microcomputer that does not include a bus arbitration function and a DMA system. The overall purpose is to provide a j-circuit.

Means for Solving the Problems In order to solve the above problems, the present invention has a built-in bus arbitration function.When a microcombination unit without bus arbitration function 1-2 uses the bus, the DMAI control device outputs the output in advance. Check the bus use request signal, and if the bus use is requested, press D.
Gives a bus use permission signal to the MA control device and uses the bus as DMA.
Open to control device.

On the other hand, if the use of the bus is not requested, the microcomputer outputs a signal that fully permits continued use of the bus.The microcomputer uses the bus.

Operation The present invention has the above-mentioned configuration, which uses a microcomputer that does not have a built-in bus arbitration function and a DAM control device that acquires and relinquishes the right to use the bus using the 7-day shifter method of bus use request signals and bus use permission signals. This made it possible to place it on a bus.

Embodiment FIG. 1 shows the bus arbitration control circuit of the present invention? Please refer to the block diagram shown below. In Figure 1, 1 is a microcomputer, 2
3 is a DMA control device, and 3 is a bus detail 1 stop control circuit. Since the functions of the microprocessor 1 and the DMA control device 2 are common, their explanation will be omitted, and the bus arbitration control circuit will be explained.

Fig. 2 0 inch bus arbitration control [details of q route. electric ζFO
At time N, when the reset signal 105 is input, the Q of the D-tibe flip-flop (hereinafter referred to as D-F/F) 4
The outputs and the Q outputs of D-F, ,'ys are set to low level. When the reset signal is released and the microcomputer starts working, first the bus request signal 1o2
is output. At the rising edge of this signal, DM
A Bus use request signal 1 output from ft1IJ control device
Sample 03.

When this signal is low level, the Q of D-F/F4 is
The output, ie, the bus available signal 101 that allows the microcomputer 1 to use the bus, goes high, and the microcomputer 1 starts using the bus. On the other hand, if this signal is high level, D-F
Q output of /F4, that is, bus available signal 10
1 is maintained at a low level state and prohibits the microcomputer from using the bus.

DF/F5 samples the bus use request signal at the rising edge of the bus request signal 102 output from the microcomputer. If this signal is at the high level, the Q output of the D-F/Fs, that is, the bus use permission signal 104 becomes high level, and the DMA control device 2 is permitted to use the bus, and the DMA control device 2 has the right to use the bus. The status signal 108 indicating that it has been acquired is set to low level. When the DMA control device 2 abandons the bus in use, it sets the bus use request signal 103 to low level, and then sets the status signal 10B to 2.Irepel.

Ma/ζ, bus use RF town signal 104 is microcombi 1
- It becomes low level by the address strobe signal 10 output from 1. At the rising edge of the status signal 108, D-, -F/F4 outputs the bus available signal 101 by interrupting the bus use request signal 103, which is already at low level 17 ('ζ).
'j (-/・Set to allow the microprocessor 1 to use the bus. It is again set to low level by the data strobe signal 106.

Effects of the Invention As described above, according to the present invention, with an extremely simple circuit configuration, all bus acquisition and abandonment can be achieved using a handshake method between a microcomputer that does not have a built-in bus arbitration function and a bus use request signal and a bus use permission signal. The DMA control devices that carry out this process can be placed on a common bus, which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the connection between a microcomputer that does not have a built-in bus arbitration function and a DMA control device in an embodiment of the present invention, and FIG. 2 is a block diagram showing the connection of a bus arbitration 'III control device in an embodiment of the invention The detailed block diagram, Figure 3, is a waveform diagram of the main signals of the bus arbitration control circuit.
DMA control device, 3...Bus arbitration control circuit, 4
．． 5...D type flip flow knob, 101.
...Bus available signal, 1o2...
Bus request signal, 103... Bus use request signal, 104... Bus use permission signal, 105...
...Reset signal, 106...° data strobe signal, 1o complete...address strobe signal, 1o8...status signal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Illustration 2

Claims (1)

[Claims] A microprocessor that does not have a built-in bus use right arbitration function and a direct memory access control device that acquires and relinquishes the bus use right by a handshake method of a bus use request signal and a bus use permission signal, the microprocessor and the direct memory A bus arbitration control device that arbitrates bus usage conflicts that occur between access control devices.