JPS61217862A - Ring arbiter circuit - Google Patents

Abstract

PURPOSE:To reduce the increase of time needed for shift of the access right by providing the function to each of plural devices having accesses to the share resources to transmit and receive the token pulses showing the access right and connecting those devices in a ring form. CONSTITUTION:Each of devices 11-1n using in common the share resources 2 contains a ring arbiter circuit 3 and an access device 4. The arbiter 3 receives the ring arbiter output of a device 13 at the preceding stage through an input and sends the token pulse to the device at the next stage through an AND circuit 3c and an OR circuit 3e as long as the access request given from the device 4 is not latched by a holding circuit 3a when the token pulse is received. When an access request is given, the output of the circuit 3a avoids a case where the token pulse passes through the circuit 3c. Then the token pulse is produced again and sent to the next stage via a pulse detecting circuit 3b and a pulse generating circuit 3d after the access request is deleted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ring arbiter circuit for sorting out conflicts when multiple devices share all shared resources such as software and access all of the shared resources. Ru.

[Conventional technology]

Conventionally, the Jinnotane ring arbiter circuit has a flip 70 knob corresponding to each device and a clip 7a knob connected in a ring shape to form a shift register.
A control circuit for ensuring that the clip 70 that latches all the level signals indicating access permission is the only one in the ring, and its connection to the clip 70 that latches all the level signals that indicate access permission. A full level signal indicating access permission is output to the output only when there is no access request from the device being accessed, and only after the device has finished accessing the shared resource. A method was used to move all access rights in synchronization with the clock. As a conventional example similar to this method, there is a token passing method of a token ring, which is one of the access methods of a local area network, and a method of passing a signal called a token, in which all access rights are transferred. In this system, access rights are given and received using a specific serial bit string called a fleet token, which indicates the free status of a transmission path, and a specific serial bit rate called a busy token. When the node making the access request detects a free token, it changes the polarity of a specific bit to a busy token.
The direction to the backward node is transmitted, and the backward node's network -
This method prohibits access to the website.

[Problem that the invention seeks to solve]

As described above, the conventional ring arbiter circuit moves the access right in synchronization with the shift clock, so it takes at least one clock period for each device to move the access right. Further, in the token passing access right movement method, a delay of at least one bit time is required for recognition of fleet tokens and reversal of bit polarity. For this reason, these grounding circuits have the disadvantage that the time required to transfer access rights increases as the number of devices connected to the ring increases.

[Dangerous means to solve the problem] In order to solve this drawback, this invention sends the token pulse money circulating in the ring as it is to the next device when the shared resource is not fully accessed. However, when accessing shared resources, the next token pulse is sent to the next device? It was made to be prohibited.

[Effect]

When shared resources are not being accessed, all supplied token pulses are delivered to the next highest device without delay.

〔Example〕

The figure is a block diagram showing an entire dormitory embodiment of the present invention. In the figure, 11 to 1n are devices that share common resources, and 2
is a shared resource. The equipment 1t to 1n is composed of a ring arbiter circuit 3, a shared resource 2t, and an access device 4 for accessing the shared resource 2t. The ring arbiter circuit 3 further includes a holding circuit 3a1, a pulse detection circuit 3b, an AND circuit 3c, a pulse generation circuit 3d, and an OR circuit 3e. When a token pulse is supplied from the preceding device, the holding circuit 3a latches the access request signal supplied from the access group ft4 at the front edge of the pulse, and
The latch is released when the access request signal is no longer supplied, and the D has a reset function.
It consists of 70 shape flips and other parts.

The pulse detection circuit 3b is enabled when the output signal of the holding circuit 3a is active, and when the token pulse supplied from the preceding device continues for a certain period of time T or more, the entire output signal is sent out.

The AND circuit 3c outputs all the token pulses from the previous device as they are when the output of the holding circuit 3a is inactive, that is, when no access request is generated, and when the output signal of the holding circuit 3a is active, the AND circuit 3c outputs all the token pulses as they are. All token pulses are not sent out. The pulse generation circuit 3d is enabled when the output signal of the pulse detection circuit 3b becomes active, and generates a token pulse tl- for a certain period of time T or more the next time the output signal of the holding circuit 3a becomes inactive. .

Note that one of the devices 11 to 1n is configured to unconditionally send out a token pulse at the time of system initialization.

The operation of the device constructed in this way is as follows. First, when initializing the system, any one of the devices 11 to 1n
Since the token pulse is sent from device 13,
Suppose that a token pulse is sent from . Fully equipped
When shared resource 2 is not accessed from 14,
Since the output of the holding circuit 3a is inactive,
The token pulse supplied from the device 13 to the AND circuit 3C is supplied to the device 14 via the AND circuit 3c and the OR circuit 3e-lr. At this time, the time that the token pulse is delayed in the fit 14 is only the propagation delay time of the AND circuit 3C and the OR circuit 3e, so the delay time is several orders of magnitude smaller than the conventional one clock time. .

And when no device is accessing the shared resource,
This token pulse circulates within a ring composed of devices 11-1n.

Next, when the device 14 starts accessing the shared resource 2, an access signal is supplied from the access device 4 to the holding circuit 3a. Then, when the token pulse is supplied from the device 13, the front of the token pulse! The access signal is latched by the holding circuit 3, and its output signal becomes active. As a result, the pulse detection circuit 3b becomes enabled and detects all token pulses that last for a period of time T or more and supplies an active signal to the access device 4, so that the access device 4
access.

When access to the shared resource is completed in the device 14, the access signal supplied from the access device 4 to the holding circuit 3a is released and the output signal of the holding circuit 3a becomes inactive, so the pulse detection circuit 3a is disabled. state, and its output signal also becomes inactive. As a result, the pulse generating circuit 3d sends out a token pulse that lasts for a period of time T or more, so that this token pulse is outputted into the ring through the OR circuit 3°. and,
Those other than the device 14, which until now have been prohibited from accessing the common resource, can now access it by being supplied with the token pulse.

The holding circuit 3a has an operating time tt to latch all access signals even if the access signal and token pulse are supplied.
i do Although this time period is determined by the propagation delay time within the holding circuit 3a, it is very short, but during this time the output of the holding circuit 3a is inactive, and during this time the output of the AND circuit 3a is inactive.
Since the token signal supplied to c is outputted, this token signal is outputted into the ring via the OR circuit 38'. However, this signal is not detected by the pulse detection circuit 3b of the subsequent device because the detection time Tf of the pulse detection circuit 3b is sufficiently short at time t. For this reason, can one device share M resources? While accessing, other devices are completely prohibited from accessing the shared resource.

〔Effect of the invention〕

As explained above, in this invention, when the shared resource is not being accessed, each device outputs the supplied token pulse money as it is, so the time that the token pulse is delayed within each device is equal to the propagation delay time. This has the effect that even if the number of connected devices increases, the increase in time required to transfer access rights is negligible.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. 11-1n...device, 2...shared resource, 3...
see ring arbiter circuit, 4... access device.

Claims (1)

[Claims] There are multiple devices and shared resources shared by those devices.
In a ring arbiter circuit in which functions for transmitting and receiving token pulses having access rights to a shared resource are connected in a ring, when the shared resource is not being accessed, the supplied token pulse is not processed and the adjacent next 1. A ring arbiter circuit comprising means for sending a token pulse to a device in a higher order, and means for prohibiting sending a token pulse to an adjacent device in a next order when accessing a shared resource.