CN1595383A

CN1595383A - Programmable bus type control port expansion module

Info

Publication number: CN1595383A
Application number: CN 200410041084
Authority: CN
Inventors: 郭万林; 冯谦
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2004-06-25
Filing date: 2004-06-25
Publication date: 2005-03-16

Abstract

The invention relates to a programmable bus control port expanded module. It is based on the PLD (programmable logic device), which is programmed to three functional modules, which are the shifting register group, the latch group and the address selecting logic. The control port expanding is realized by the series/parallel converting and latching. Moreover, the flash control port can be acquired through the built-in chip address selection logic and the bus network constituted by multiple control port expanded modules. Each module is composed of a single PLD, which guarantees a significant number of control ports acquired, which can't be acquired by the special input/output port expanded chips. The multiple modules of the bus are selected by the address selecting logic, the module address pin, and the most significant bit of the serial shift. Only when the most significant bit is consistent to the module address pin, the output of the control port can then be updated. The module is convenient to use, especially suitable for the measuring and controlling based on various embedded systems or the computer.

Description

Programmable bus formula control port expansion module

1. technical field

The present invention relates to a kind of programmable bus formula control port expansion module, utilize it can obtain that special-purpose input and output (I/O) port extended chip can't be compared, a large amount of control ports, and can utilize a plurality of control port expansion modules to form network bus, obtain the magnanimity control port.This module is applicable to based on the measurement of computing machine and various embedded systems and control.

2. background technology

Port expansion is based on one of work that often runs in the electronic system design of microcontroller or single-chip microcomputer, is used to control external unit or communicates with.Though microcontroller or single-chip microcomputer have carried the input/output port of some, wherein most of port is the multifunctional multiplexing port, can be used as functions such as serial communication, pulse-length modulation output, capturing unit input, also can be used as common port.Relatively nervous when system resource, or when big, must carry out the port expansion to the demand of port.This is especially common in the higher measurement and control system of various automaticities.

The private port extended chip has parallel extended chip and serial extended chip, comparatively speaking, utilizes universal serial bus to carry out the port expansion, can obtain more port, takies less resources.Serial bus port extended chip commonly used mainly uses SPI (Serial Peripheral Interface Serial Peripheral Interface (SPI)) bus, I2C bus.The production firm of serial port extended chip mainly is MAXIM company and PHILIPS company.The product of the spi bus interface of MAXIM company all can carry out cascade with the form of daisy chain.In the I2C bus device, generally use 3 address wires, it is inserted high level or low level, can on a bus, hang 8 similar devices at most.The address pin of the I2C bus extended chip of MAXIM company can also link to each other with serial data bus or serial clock bus, has expanded the quantity of the similar device of hanging on the same bus, has strengthened extended capability.But the expansion quantity of single port extended chip still seldom, and requirement and spi bus or I2C bus interface, and this is not that each microcontroller or single-chip microcomputer have.Wherein expand quantity greater than 20 chip, price high and buy difficult, especially when the port quantity required is very big, must use multi-disc port extended chip, cause system complex, bulky.

Programmable logic device (PLD) (PLD) is newer integrated circuit (IC) products, has characteristics such as high function, high integration, high-performance, high reliability, low cost, uses very extensive.Use programmable logic device (PLD) to design, have characteristics convenient, flexible, that the design cycle lacks, is easy to revise.This device is not needed special programmable device and complicated flow process, only need a root interface cable, just order and data can be downloaded in the device, upgrading is extremely convenient with improvement.The PLD device uses flexibly, pin is abundant, powerful, be easy to characteristics such as modification, utilizes the PLD device, can obtain that special-purpose input/output port extended chip can't be compared, a large amount of control ports.

3. summary of the invention

Purpose of the present invention provides a kind of programmable bus formula control port expansion module, satisfies in the measurement and control system demand to a large amount of control ports, and easy to use, simple and reliable.

Programmable bus formula control port expansion module of the present invention, adopt programmable logic device (PLD) (PLD), it is programmed for three functional modules of shift register group, bank of latches, address selection logic that link to each other with microcontroller or computing machine, the output of shift register pack module is connected in the bank of latches module input with opertaing device respectively, with the address selection logic module input that links to each other with low level or high level, the output of address selection logic module is connected in the bank of latches module input, with the form that serial is changed and latched, realize the control port expansion.And can select logic by built-in chip address, and utilize a plurality of control port expansion modules to form network bus, obtain the magnanimity control port.Its feature also is, the address selection logic module input that links to each other with low level or high level and the carry-out bit of shift register pack module by the address selection logic module, are realized the bus type expansion.

4. description of drawings

Fig. 1 is a functional schematic block diagram of the present invention

Fig. 2 is to use the connection block diagram of module of the present invention

Fig. 3 is an enforcement block diagram of implementing example of the present invention

Fig. 4 is the sequential analogous diagram of enforcement example of the present invention

5. embodiment

As shown in Figure 1, programmable bus formula control port expansion module of the present invention adopts programmable logic device (PLD) (PLD), is programmed for shift register group, bank of latches, three functional modules of address selection logic.Wherein, CLK, DATA_IN, CLR pin are respectively clock input, serial data input, the zero clearing input end of shift register group; OUT0～OUTk is the output terminal of latch respectively, i.e. the output of port expansion module; LATCH, ADDR0, ADDR1 ..., the ADDRn pin is latching of module and address selection pin, they are through the latch signal of the output (LATCH2) after the logical operation as bank of latches.The data input that shift register receives serial realizes the serial conversion.Latch is used for latching of data, the highest several (figure place is identical with the address pin number) of latch signal (LATCH pin), address selection pin and serial-shift, after process address selection logic module is carried out logical operation, produce or do not produce the latch pulse (LATCH2) of bank of latches, realize that a plurality of modules on the bus are selected.When having only value when the most significant digit data of serial-shift and module's address pin consistent, the latch signal of latch is just effective, and control port output just can be updated to the output of shift register group.Wherein the value of n and k and port demand, PLD device performance, resource are relevant, and the maximum port number that can expand is 2 ⁽ⁿ⁺¹⁾* (k+1) individual.

The connection block diagram of use module of the present invention as shown in Figure 2.Compare with the private port extended chip, this module only need be used several input and output (I/O) port of single-chip microcomputer or microcontroller or DSP to connect and get final product, and simple and convenient, applicability is wide.The CLK of module of the present invention, DATA_IN, CLR, LATCH pin are connected with micro controller I/O port respectively; (ADDR0～ADDRn), connect low level or high level respectively realizes addressing to address pin; OUT0～OUTk is the port output pin of expansion, connects the equipment of the port controlling that is expanded respectively.

According to the present invention, an exemplary concrete enforcement example as shown in Figure 3.This example has been expanded 48 ports, and contains 3 bit address, as uses a plurality of modules of the present invention to form bus, can expand 2 at most ³* 48=384 control port.In implementing example, the dsp chip TMS320LF2407 that selects TI company for use selects the realization carrier of complex programmable logic (CPLD) the chip EPM7128SLC84-15 of altera corp as this example for use as microcontroller.

According to the theory diagram in the embodiments of the invention, use the software Max+plus II of altera corp to design, realize the described function of example of the present invention, and carried out software emulation simulation and hardware experiments checking.The software emulation Simulation result as shown in Figure 4, hardware experiments checking result is correct.

Those skilled in the art it will be appreciated that, the present invention is according to the patent statute demonstration and described the present invention, can be according to content of the present invention, in the embodiment that is disclosed, make and revising and change, as change selected chip, change Extended Capabilities Port quantity, change address size etc., and do not deviate from the spirit and scope of the present invention.

Claims

1. programmable bus formula control port expansion module, it is characterized in that, adopt programmable logic device (PLD) (PLD), it is programmed for the shift register group that links to each other with microcontroller or computing machine, bank of latches, three functional modules of address selection logic, the output of shift register pack module is connected in the bank of latches module input with opertaing device respectively, with the address selection logic module input that links to each other with low level or high level, the output of address selection logic module is connected in the bank of latches module input, with serial conversion and the form that latchs, the expansion of realization control port, and can select logic by built-in chip address, utilize a plurality of control port expansion modules to form network bus, obtain the magnanimity control port.

2. programmable bus formula control port expansion module according to claim 1, its feature also is, the address selection logic module input that links to each other with low level or high level and the carry-out bit of shift register pack module, by the address selection logic module, realize the bus type expansion.