Introduction
In application domains and so on industrial control, information electrical appliances, have the massive embedded equipment, but these equipment are many only then the serial port, the CAN main line and so on simple network interface, traffic capacity is limited, some even are at the isolated operation condition. How to let these take the monolithic integrated circuit as the core embedded system turning on ethernet, and carries on the long-distance monitoring through the network to them, is in the current electronic world research hot spot. TCP/IP in Intemet and the majority local area network’s success applications, had already proven its formidable function. If realizes the TCP/IP agreement and embedded system’s union, the embedded system networking question can obtain the effective addressing. At present, the embedded system networking mainly has the following several kind of plans:①EMIT, take PC or other upscale computers as a gateway, equipment and so on CAN, RS-232 turns on the heavyweight network;②Uses 32 MCU real-time operating system, the upscale MCU function is formidable, may realize the complex operation, but needs to have the RTOS support, this kind of plan’s cost and is high to development personnel’s request;③Uses Scenix 8 MCU, in addition the hypothesized software package, realizes the multi-duty operating system, moves the TCP/IP agreement stack.
This article proposes based on the network monolithic integrated circuit’s embedded long-distance supervisory system plan, may realize lightweight networks and ethernet’s and so on serial port, CAN main line interconnection. This plan has the volume to be small, performance-to-price ratio high characteristic.
1 system’s composition
Based on the network monolithic integrated circuit’s embedded long-distance supervisory system by the master-control unit, ethernet functional modules and so on turning on module, CAN network turning on module, 1-Wire network, serial port network, memory electric circuit, real-time clock, power source module and monitoring circuit is composed. Its functional block diagram as shown in Figure 1.
(1) master-control unit
Used original Dallas Corporation’s high performance 51 essence network monolithic integrated circuit Ds80C400, the interior integrated 1 10/100M the ethernet controller (MAC),3 general full-duplex serial port, 1 CAN2.0B controller, 1 1.Wire controller. In the MCU internal 64KB ROM procedure contains complete TCP/P the V4/6 agreement stack; May visit the 16MB storage space; Has the special low address mouth; 4 data indicators; Has the 2x/4x clock duplicator, the highest operating frequency may reach 75MHz.
(2) ethernet turning on module
Using integrated MAC, passes physical level component PHY and the ethernet is connected; MAC has standard media irrelevant connection MII. In the design PHY uses has automatic consultative function DP83846A, external connection network transformer 20F001N. In the work process, may through the MII management main line establishment working pattern. PHY and ethernet controller’s connection as shown in Figure 2.
MAC has the special receive transmission buffer, may carry on the visit through MOVX; MAC also has buffer control unit BCU, order/condition register CSR, address compositions and so on examination module, power source management unit, is mainly responsible for ethernet’s receiving and dispatching activity by BCU, reduced the CPU participation, has guaranteed the ethernet receiving and dispatching efficiency.
(3)CAN network turning on module
Through the integrated CAN2.0B controller, the external connection CAN transceiver and the CAN network is connected. In what the design uses is TI SN65HVD230, it has the low cost, the low power loss characteristic.
(4)1-Wire network
Are connected through a 1 Wire bus control unit and 1-Wire non-erasable storage DS2502-E48, provides the physical address to the ethernet controller (the MAC address).
(5) serial port network
Through the monolithic integrated circuit interior integration’s full-duplex serial port, may be connected with the serial port equipment. For matches with the exterior RS-232 level, external connection transceiver MAX560CAI (may also use MAX232, MAX3233 and so on), it has 4 inputs, 5 outputs. Monolithic integrated circuit’s serial port 0 use for with the development machine to be connected, the serial port 2 take DTE, has the complete class pilot wire, uses for to be connected with the serial port equipment.
(6) power source
In the electric circuit each kind of component’s working voltage has 3.3V, 1.8V and 5V and so on, uses MAX832, MAX682 and MAXl792, provides 3.3V, 5V and the 1.8V voltage separately.
(7) monitoring circuit
Selects MAX825T (threshold voltage 3.08V) to monitor master-control unit’s 3.3V supply voltage, when the voltage is lower than 3.08V, has the reliable replacement.
(8) real-time clock
Provides the accurate time to the system, is advantageous for the understanding system mode, for instance gain data acquisition time and so on.
(9) storage location
Ds80C400 has the special low position address wire P7 mouth and the special labor program memory selects patches or strips of land as worth saving for seed the signal (CEO~CE7) and the data-carrier storage selects patches or strips of land as worth saving for seed the signal (PCEO~PCE3), addressable 16M procedure space and 4M data space. Selects AM 29 F 040 B 170 (the Flash,2 piece) to take the program memory, HM6285 12LFP-7 (the SRAM,2 piece) takes the data-carrier storage. Meet separately SRAM and Flash in the surface, the surface, the surface, the surface. Internal 64KB R0M when system initiation, carries on the initialization to SFR, thus SRAM, Flash map the space which separately Table i shows. DS80C400 interior and each kind of controller related memory block and ROM address mapping like table 2. These buffers in the chip, have the rich visit and the operational order, the system have the high integration rate and the volume of goods handled.
2 programming method
In DS80C400 integrated 64KB ROM, has industrial standard’s TCP/IP the v4/v6 agreement stack, takes the lead-like scheduler program and network vectoring procedure, serial port guidance loading operation. The network vectoring procedure and the serial port guidance loading operation may load the application procedure. In the application through the exterior pin’s disposition, chooses internal ROM to carry out the flow. When system initiation, ROM 0 carries on the initialization to monolithic integrated circuit’s serial port, MCU through the serial port 0 and the development main engine correspondence, reads in the procedure to F1ash.
The network vectoring procedure uses the internal TCP/IP agreement stack and the task scheduler, may carry on application procedure downloading through the ethernet, realizes the procedure online renewal. The application procedure uses Java to develop, provides software development tool bag TINI SDK with the aid of Dallas Corporation, the majority of work complete on the development main engine; May use free Java the SDK tool or the integrated development environment, raises the programming efficiency. TINI SDK the DS80C400 in hardware part hypothesized is the Java kind, thus to the actual hardware’s operation, will transform into to the object method transfer, uses Java not to request the exploiter inquire deeply system’s hardware constitution. TINI SDK has provided the Java procedure movement environment, develops the Java application procedure on the main engine after the transformation, then moves on the target system. Under the movement environment’s support, may develop the function perfect embedded Web server, thus realizes the equipment running status long-distance monitor and the control. In DS80C400 has the 1KB expansion warehouse space, has the support higher order language development physical foundation. TINI SDK is precisely in this foundation, has provided the Java movement environment, thus may develop the multi-thread application procedure. Take develops the serial port equipment to the ethernet server’s data stream transmission procedure as the example, contains the main thread and the transmission, the receive thread. Program structure like chart 3 and shown in Figure 4.
3 conclusions
This system not only may develop the embedded equipment’s traffic capacity, lightweight networks and the ethernet and so on RS-232, CAN is connected, for instance realizes the serial port equipment and the ethernet server’s data stream transmission, carries on the monitoring through the ethernet server to the serial port equipment; May also substitute for the original control device, controls the field apparatus directly, may use this system to realize the network sensor, the remote control equipment movement, long range data gathering and so on. The system also has the big capable of extension, may need to carry on the expansion according to the application, like changes memory’s capacity and so on. When the system realizes, must according to the concrete need choice appropriate capacity and the access time memory, uses the appropriate addressing mode; Selects the appropriate interface circuit and guarantees the correct connection and the disposition. On the other hand, this chip’s integrated function are many, when the system has the problem, the localization is quite difficult. But this plan does not rely on PC or the upscale monolithic integrated circuit, realizes 8 machine to turn on Internet directly; Needs the periphery component to be few, the system cost is low; The development cycle is short, the development cost is relatively low, has the practical application value.
