JPH01297758A - Data transmission method between microcomputers - Google Patents

Abstract

PURPOSE:To permit access from both a first microcomputer and a second microcomputer in word unit by performing data transfer between the first microcomputer of a certain number of bits and the second microcomputer of bits of integer times the bits of the first microcomputer via plural shared memories of above number of bits. CONSTITUTION:The shared memories 3 and 4 of either bits are provided between the microcomputer 1 of either bits and the microcomputer 2 of 16 bits. In the microcomputer 1 of eight bits, the read/write of either bits is performed by selecting the shared memory 3 or 4 by a converter 5 based on the address at the time of reading/writing data. Also, in th microcomputer 2, the read/write of the data of 16 bits is performed by performing the readout or write of high- order data on the shared memory 3 and low-order data on the shared memory 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data transmission method between microcomputers, and in particular, for example, a method for transmitting data between microcomputers,
This invention relates to a data transmission method for accessing a shared memory between computers with different bus configurations, such as 16-bit microcomputers.

[Conventional technology]

Conventionally, regarding data transmission using shared memory, Elec 1 ~ Ronix August 17, 1978 "Dual Port RAM Hyx Sloops 1 ~ In-Pra 1 He Outputs 1- Con 1- Laura Bau 1
"Electronics A" pages 1 to 5
August 17, 1978 rDnal-por
t RAM l1ikes Throngput i
n Input-output Controller
Board J).

[What the invention seeks to solve'i11! [Problem] The above conventional technology has the same data bus configuration (for example, 8-bit bus,
16-bit I-bus, etc.), and there is no consideration given to accessing shared memory between computers with different data bus configurations. When data is transmitted via shared memory in a computer, 1 is used only when accessing the shared memory.
8-pin data bus for 6-bit microcomputer
- It is necessary to switch to a bus or use a bus configuration that allows access in units of words, and mask the upper or lower part of the data. In this case, the 8-bit i microcomputer is 16-bit 1-
Depending on how the microcomputer is accessed,
There is a problem in that data must be written every other byte to the negative or lower digit of the shared memory.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission method between microcomputers that allows mutual microcomputers to efficiently access a shared memory without using a program.

[Means to solve the problem]

The above purpose is to connect a first microcomputer with an arbitrary number of bits, for example, 8 bits, and a second microcomputer with a number of bits that is an integer multiple of the number of bits, for example, 16 bits. said second microcomputer transmits data via said plurality of shared memories used by said two microcomputers, said second microcomputer transmits data to each said shared memory. Ri-
1- When writing, the Amires decoding unit and address bus select each shared memory so that the data can be accessed in words in bits that are multiples of the above integer. When data is transmitted for each number of bits and the data is read/written from the microcomputer 1-2 to the shared memory 1, the converter is This was achieved by switching each of the shared memories mentioned above and transmitting data.

[Effect]

A 16-bit 1-microcomputer has a decoder section that can access shared memory in units of 2-1, and thereby accesses the shared memory. The 8-bit data bus is separated into shared memories for upper and lower digits, and the shared memory can be accessed by a 16-bit microcomputer or in word units. When an 8-bit microcomputer accesses a shared memory, the converter uses the first 8 bits to access the upper digits of the shared memory, and the next 8 bits to access the lower digits of the shared memory. Therefore, it is as if shared memory is being accessed in units of words. As a result, when an 8-bit microcomputer accesses the shared memory, it can access the normal 8-bit 1 via the bus, and when a 16-bit microcomputer accesses the shared memory, it can access the 16-bit 1.
It is possible to access the word 1 of ~ in units of units, and data transmission between microcomputers can be performed efficiently.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3.

FIG. 1 is a schematic configuration diagram of a data transmission section between 8-bit I to microcomputer and ]6-bit 1\microcomputer for explaining an embodiment of the inter-microcomputer data transmission method of the present invention. Figure 2 is 8th hit 1- of Figure 2.
A timing chart when the microcomputer 1 accesses the shared memory, Figure 3 shows the 16-bit 1 in Figure 1.
Fig. 5 shows a timing chart when the microcomputer 2 accesses the shared memory.

In Figure 1, 1 is an 8-bit microcomputer, 2 is a 16-bit microcomputer, and the shared memory has upper digits so that the 16-bit 1 to microcomputer 2 can access the shared memory in word units. It is divided into a shared memory 3 and a lower digit shared memory 4. 16-bit l-microcomputer 2 is shared memory 3
, 4, the part 10 to Atres decode l
and select the shared memory using the address bus 6. Next, the upper data selection signal 12 and the lower data selection signal 3 are output in sequence, and the data in the shared memory when each is selected is transmitted through the 2nd data bus 7 and the lower data bus 8.
Data is exchanged with the 6-bit I-microcomputer 2 in units of words 1. When the 8-pin microcomputer 1 accesses the shared memories 3 and 4, the data bus 9 does not have 8 pins, so the address bus 6
The shared memories 3 and 4 are alternately switched by the converter 5 and the read/write signal 11 is used to exchange data.

As shown in FIG. 2(a), when the 8-bit microcomputer 1 outputs the address to be accessed in the shared memory from the address bus 6, if the signal from the converter 5 is the upper digit address, then as shown in FIG. ), if the signal 5A is a lower digit address, the signal 5B is output as shown in FIG. 2(c). When the signal 5A is output from the converter 5, the second
The current data is placed on the data bus 9 in FIG. 2(e) in synchronization with the current paste-1-'/write signal 11 in FIG. 2(d). When the signal 5B is output, the data at that time is similarly placed on the data bus 9.

Figure 3 shows timing charts 1 to 3 when the 16-bit microcomputer 2 accesses the shared memory.
As shown in FIG. 3(a), when the address to be accessed in the shared memory is output on the address bus 6, an output signal is output from the decoder 10 as shown in FIG. 3(b). next,
As shown in FIG. 3(c), the second data selection signal 12
is output, and in synchronization with this, data is loaded onto the upper data bus 7 as shown in (e). Next, Figure 3(d)
As shown in (f), the lower data selection signal 13 is output, and in synchronization with it, data is loaded onto the lower data bus 8 as shown in (f).

According to the method of this embodiment, when 8-bit microcomputer 1 and 16-bit 1-microcomputer 2 transmit data via shared memories 3 and 4, access to shared memories 3 and 4 is controlled by 8-bit microcomputer 1 and 16-bit microcomputer 2. 1 is accessed in units of bytes of an 8-bit bus, as if they were accessed in units of words, and the 16-bit microcomputer 2 is accessed in units of words of a 16-bit bus, which has the effect of allowing efficient use of the shared memory.

In the above embodiment, the 8-bit microcomputer 1,
Although the 16-bit microcomputer 2 has been described as an example, the present invention includes a first microcomputer having an arbitrary number of bits and a second microcomputer having a number of bits that is an integral multiple of the number of bits.

In other words, for data transmission between an 8-bit microcomputer and a 32-bit microcomputer, a 16-bit microcomputer and a 32-bit microcomputer, and a 64-bit microcomputer, the number of shared memories is determined by the bit ratio (integer multiple) of both microcomputers. ), and by selecting each shared memory using an address decoder and a converter.

〔Effect of the invention〕

- According to the invention as described, the first
and a second microcomputer whose number of bits is an integer multiple of the number of bits - 8 = When transmitting data via a shared memory, the first microcomputer is connected to the If we assume that the microcomputer is a 16-bit microcomputer, the shared memory access will be in 8-bit byte units, as if the microcomputer were accessing in word units.
A 16-bit microcomputer can access a 16-bit bus in units of words, and has the advantage of being able to use shared memory efficiently in terms of hardware configuration, regardless of the program.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a data transmission section between an 8-bit microcomputer and a 16-bit microcomputer for explaining an embodiment of the data transmission method between microcomputers of the present invention, and FIG. Timing chart i~ when an 8-bit microcomputer accesses the shared memory; FIG. 3 is a timing chart 1~ when the 16-bit microcomputer shown in FIG. 1 accesses the shared memory. 18 Hint I/Microcomputer, 216 bits 1~Microcomputer, 3 Upper digit shared memory, 4 Lower digit shared memory, 5 Converter, 6 Address bus, 7
- data bus, 8 lower data bus, 9 data bus, 0 A1 to address code section,] tree 1 to /rai 1
- signal, 12 Upper data selection signal, ] 3 Lower data selection signal.

Claims (1)

[Claims] 1. A first microcomputer with an arbitrary number of bits;
a second microcomputer having a number of bits that is an integral multiple of the number of bits, and transmitting data via a plurality of shared memories having the number of bits used by both microcomputers, wherein the second microcomputer When the microcomputer reads or writes data to each of the shared memories, the address decoder and the address bus select each of the shared memories and write arbitrary bits so that the data can be accessed in words in units of bits that are multiples of the integer. When the first microcomputer reads and writes data to each of the shared memories, the first microcomputer can access the arbitrary bit numbers as they are;
A method for transmitting data between microcomputers, characterized in that data is transmitted by switching between the respective shared memories using a converter.