Abstract: The design has realized a set based on the software radio the software MODEM experiment system, this system hardware take TMS320C6711 digital signal processor (DSP) as a core, realizes the software radio multi-service pattern modulation demodulation function, and designs the hardware interface to complete with the main engine real-time communication. Designs the hypothesized instrument control in the main engine to demonstrate the platform, realized to modulated the demodulation service pattern the real-time choice and the measured data real time display.
Key word: Software radio; Hypothesized instrument; DSP; MODEM
The software radio the basic philosophy is take open, expandable, the structure most Jan’s hardware as the general platform, with may promote the multi-correspondence function, may replace the software realize as far as possible. Its central thought is: Constructs one to have standardized, the modular general hardware platform, and loads through the software realizes each kind of wireless communication function one kind of open style architecture. The modem is the software radio the key technologies link, is one of software radio engineering research central contents, modem’s software is realizes the software radio openness, versatile key one step.
System principle
This system designs in view of the university teaching, as the core build software radio teaching demonstrates the platform take TMS320C6711 digital signal processor (DSP), to manifest the software radio fully as far as possible the design concept, the hardware platform as the core build has realized hardware’s modulation, openness and programmable take DSP, realized data receiving and dispatching, the enlargement through the hardware, programmed in DSP realizes FM, DSB, QPSK, QAM and so on many kinds of service pattern modulation demodulation functions. The system most major characteristic is uses the plan which general-purpose calculator and the DSP processing unit unifies, in the system each kind of man-machine connection and the control function, the memory demonstration function by PC machine completes, but each kind of real-time task gives DSP to complete, displays DSP high speed fully place
Manages ability and the PC machine flexibility.
System structure
This system structure as shown in Figure 1. It is composed of the DSP data processing board and the PC man-machine interface control onstage. And the DSP data processing board take DSP (digital signal processor) as the core microprocessor core, the external connection data transmitter-receiver set and the DSP periphery hardware equipment, the data receive transmitter installation carries on gathering and the output to the external signal, enlarges through the power amplifier the wanted signal, because uses DSP is the digital signal processing chip, therefore also
Figure 1 system structure diagram
Needs a/D, D/A switching circuit, will gather the simulated signal transforms the digital signal, after and will process the digital signal transforms the simulated signal output. In order to satisfy the main engine and the periphery hardware’s correspondence, must use DSP and the host interface, we (host interface) realizes DSP and the PC real-time communication in the hardware through HPI. Has demonstrated the platform in PC machine with the software design hypothesized instrument control, realizes to the hardware processing control and the demonstration, the user may the data-in choose each kind of modulation demodulation service pattern in the hypothesized instrument platform front panel, and reads in through the data communication interface the data PC machine, in the hypothesized instrument demonstrates in the platform by the graphic mode real time display data result.
TMS320C6711 chip synopsis
Because modem’s design realizes is based on TI Corporation’s TMS320C6711 chip, therefore, structure carries on the brief introduction in here to TMSC67x the series CPU. TMSC67x the series CPU interior takes including the procedure refers to the unit, the program execution organization, the chip testing and the simulation port as well as the control logic. The procedure takes refers to the unit is connected by the program bus and the internal program memory. Program execution organization including 2 symmetrical data channels (A and B), 2 symmetrical general register groups, 2 group of symmetrical function units (each group of 4), control register group and control logic as well as interrupt logic and so on. Each group of data path has the read-in and the memory (writes) the data bus and the internal memory is connected.
TMSC67x series CPU uses the Harvard structure, its program bus and the data bus separate, take the instruction and the executive order may the parallel running. The C67x series chip’s program bus width is 256bit, each time takes refers to the operation takes 8 instructions, is called one to take refers to the package. Outside the piece memory and the main line do not divide, the two are unified. Complete storage space (including program memory and data-carrier storage, internal and outside piece) take byte as unit unified address.
Main engine correspondence connection design
In the system main engine correspondence connection HPI is TI in Corporation digital signal processor (DSP) uses in with the main engine carrying on the bidirectional data communication 8 bit parallel connection. HPI is called the host interface, is TI on Corporation high performance DSP disposes carries on the correspondence with the main engine the internal peripheral device. When traditional monolithic integrated circuit and main engine (for instance PC machine) connection, needs to expand the additional chip outside the piece. If uses with the main engine shares RAM the way, then wants outside the piece to expand RAM and triggering, the lock saves and so on chips, by now the main engine might stochastic or the entire block place visit shares RAM through the DMA way; If does not request the main engine direct access from machine the data, may also adopt expands the FIFO chip the way.
Moreover, when from machine needs to interrupt, outside the piece at least must again expand a piece of latch.
The HPI host interface above these function integration in the DSP chip, will cause it with main engine’s connection simplification, does not need regarding the DSP system outside the piece to expand the above use the chip. HPI has two workings, uses in common addressing system (SAM) and only main engine addressing system (HOM), this system uses uses in common the addressing system, the main engine and DSP can the addressing HPI memory, the main engine places in the HPI memory after the DSP transmission control word as well as the DSP processing real-time data to supply the visit. Because HPI is the integration in internal, therefore the main engine may achieve the very high access speed, moves frequency in the SAM way and the DSP basic frequency quite, adapted DSP to the high velocity request.
The system uses the HPI connection mainly to turn on the HPI port through transfer dynamic link storehouse document dsk6×11hpi.dll in function dsk6x-hpi-open, such system DSP carries on a series of job processing, and through the HPI port to the DSP read-write data, transfers in dynamic link storehouse document dsk6×11hpi.dll function dsk6x-hpi-close to close the HPI port again.
Software design
Software architecture
Software architecture as shown in Figure 2. Establishes the hypothesized control display system’s goal is must realize the onstage software and the first floor hardware connects is forming a complete system together, this system uses the dsk6×11hpi.dll dynamic link storehouse document to realize with TMS320C6711DSP the board HPI correspondence. The PC machine execution application procedure, the load algorithm to the DSP end, completes the data transfer which and will need to process after the DSP, DSP computation feeds in the data PC, the entire process controlled by PC starts, processing, the conclusion and so on, in such software architecture needed to have the control demonstration visualization user interface, simultaneously, the software must need the software and hardware interface routine with the concrete hardware connection. In DSP, to realize the multi-service pattern modulation demodulation to need the signal modulation demodulation software, must apply the algorithm in the concrete hardware platform, but also needs the hardware platform the driver.
Figure 2 system software structure diagram
DSP programming
The system must realize many kinds of service pattern modulations and the demodulation, this part of functions complete through the DSP software, this system has realized FM, DSB, QPSK, DQPSK and so on many kinds of service pattern modulations and the demodulation. In order to enhance the procedure the flexibility and the probability, many kinds of service pattern modulation demodulation programmings, in the identical project document and translates downloads to DSP, when MODEM board card work, through the PC onstage transmission’s control word, chooses the different procedure entrypoint and the transfer different modulation demodulation function chooses the different modulation demodulation way. And demodulates the part in the analog modulation, according to the different modulation system’s characteristic, has chosen AM, DSB and FM3 plants the modulation system to realize. Have realized QPSK and QAM in the digital modulation and the demodulation part.
LabVIEW programming
Because in realizes the main engine and in the DSK board correspondence process involves to successively the order, namely the establishment connection, the replacement board, reposition DSP, to turn on the HPI port, the loading sequence, the execution read-write operation, to close HPI, to close the connection finally, these operations carry out in turn. Therefore in software design time uses the smooth structure to the procedure, when simultaneously the subroutine has involves to writes the operation must to many variables carry on writes the operation, also has used the smooth structure.
But must realize can choose debugging on the contact surface the type, again according to debugging type execution different procedure, then must use the choice structure in the flow chart. This system contains in the labview contact surface design has chooses the storehouse document function input which, the output parameter establishment part for the user the modulation system the part, some flow chart transfer, but also includes a graphical display component, realizes to the DSP memory readout demonstration. May divide 5 parts to design this contact surface: In view of function call’s time parameter input, designs 1 5 parameter composition the module, including for the DSK board definition handle, the definition repositions when the DSP chip the port pattern as well as inducts the pattern, the load COFF document name, to use the board configuration files the name and deposits the position; In view of modulation system’s choice and the modulation time-variable quantity’s change, designs 1 5 parameter composition similarly the module, including the carrier frequency, the direct component, the enlargement increases, the FM index as well as the modulation system; In view of when a on module in modulation changes the variable, designs 1 8 parameter composition the module, these parameters are the variable length which and the address which in the establishment a module reads in deposits in DSP; Aims at again reads the programming 1 3 parameters the module, must read the DSP in data the need, establishes a length, the initial address and a main engine buffer; Last module is a profile demonstration module.
LabVIEW and DSP signal procedure
Demonstrated that the contact surface software develops in Lab under the VIEW becomes, may realize the mainframe program (Lab the VIEW procedure) with the DSP correspondence, namely the DSP memory carries on the read-write operation. Lab the VIEW procedure by the front panel, the flow chart and the icon \ coupling is composed. The front panel is the man-machine contact, the exchange window, simulates the actual instrument, mainly controls and the display by some are composed; The flow chart is the procedure code, when is the LABVIEW procedure core spot, the program run, the front panel will control a value to transmit for the flow chart carries on processing and the operation, will then transmit again the final processing result for front panel’s display demonstrated that will be advantageous for the user observation; The icon/coupling is the procedure graphic mark, when is other high-level procedures transfers the graph code and the connection port.
Because uses CCS to observe DSP the data profile to be quite troublesome, the function which moreover after using in observes the revision variable, to produce, must complete the original program to revise, then the recompilation, loads to DSP, finally gathers profile this kind of complete process. Therefore this hypothesized control display system through transfers dynamic link storehouse function dsk6×11hpi.dll which CCS provides, according to certain communication precedence method and the thought project approach diagram, may realize the mainframe program conveniently (the LabVIEW procedure) and between the DSP correspondence. the dsk6×11hpi.dll dynamic link storehouse function has contained 12 connection functions, these 12 connection function carries out the different function separately, like realizes with DSK the board establishment connection, the replacement board, the closure connection and so on, these connection function contained some parameters, the input value has been different, representative’s meaning was not same.
(Calling Library Function Node) transfers the dsk6×11hpi.dll dynamic link storehouse function in LabVIEW with the storehouse function node, realizes with the TMS320C6711DSK DSP correspondence. So long as establishes, the step complete (to establish connection first accurately, then repositions board, to reposition DSP, to turn on the HPI port, loading sequence, execution read-write operation, to close HPI, only then to close connection finally), might realize corresponds. Certainly, after the programming completes, must let the LabVIEW procedure and the DSK board carries on system jointing shake down testing, a group of data demonstration which reads from the DSP memory in graphical display contact surface, through graph window observed data to be whether complete, be accurate.
System real-time processing function’s PC-DSP realizes jointly
After the front software and hardware project work completes, the work is completes the main engine and DSP unites the real-time data processing. After using LabVIEW designs the front panel, the flow chart and the icon, the coupling, so long as the node transfers the establishment to be accurate and the segment is correct, the procedure might move. The electricity and establishes accurately after for the DSP board on, may the debugging routine.
First, needs (dynamic link storehouse function) to input, the output parameter and the input before jointing shake down testing to the node controls a establishment to carry on the inspection. In the debugging process, we may use the probe to survey the input, the output value, observes the procedure whether to move correctly. Then The establishment connection, the DSP program load to the DSP chip, should better put by now the transfer storehouse document to and COFF (the .out document) under the identical table of contents. If program load successfully, after the main engine and the DSP board have established the connection, will transfer dsk6x-hpi-write and the dsk6x-hpi-read function returns value will not be 0, if the returns value will be 0, moreover the node will transfer the establishment not to have the question, at this time needs to inspect the board whether to connect normally.
Regarding transfers dsk6x-hpi-write and the dsk6x-hpi-read function, in which establishment is very important, so long as has a scrap establishment not to be successful, the procedure is unable to work. This aspect needs us to this function input, the output parameter to understand. Here pointed out that p-length and dest-addr the data Pass establishment should establish Pointertovalue, is also aims at this number the address. But should establish Array regarding the read module p-buffer data type (array), Array Format (array form) should establish the indicator. These established have been successful, the procedure only then could the normal operation. Program load successfully, the function returns value is not zero, may work following Xu. dsk6x-hpi- write and the dsk6x-hpi-read function’s returns value had demonstrated this operation is successful, may also read normally the data from HPIRAM delivers the PC hypothesized instrument program data entrance, then demonstrates again it by the graphic mode. Figure 3 is when the PC-DSP teamwork work demonstrates under the QPSK debug mode work in the hypothesized instrument front panel, reads out in DSP from HPIRAM the modulation signal (, in profile demonstrated that in chart expresses).
Figure 3 PC-DSP joints shake down testing the QPSK modulation oscillogram
Concluding remark
This set the software MODEM experiment system has realized the multi-service pattern modulation demodulation based on the software radio in the identical system, and this system has the man-machine connection and the control demonstration function, will process the data to be advantageous for the observation and the analysis by the graphic mode real time display. In the system each kind of man-machine connection and the control, the memory demonstration function realizes by the general-purpose calculator, but the data acquisition and the modulation demodulation and so on real-time processing duty hands over by DSP completes. Has displayed general-purpose calculator’s flexibility and DSP high speed real-time processing ability fully.
