With the TNC3, a hardware was possibly available with her/it it for the first time was to be reached throughputs with more than 1MBit/s. Since only shows one year the 1.2288 MBit/s fullduplex-Links between DB0AAA and DB0PRT that these Throughputs also over Linkstecken usable is. Skeptics immediately asked the question how this immense capacity can be used at all, because there was up to now no suitable hardware, that a so fast connection between a Digi and a Mailbox- or WWW-Server could produce. Virtually becomes at the moment all Ankopplungen of amateur-radio-servers with help of asynchronous V.24-Interfaces realized. These can with a baud rate of 115k2 at best can be driven. Beside this upper-border, it appears in the practice that these serial connections are not only slowly but also mistake-susceptible. To be silent completely, of the Interrupt-Last which through the asynchronous communication in the Server originates. She/it forces also the fastest server-calculator to the knees. Plainly, that was sought after an alternative to the serial interface for a long time.
Ethernet has established itself to the standard-network for LANs in the meantime. The necessary PC-Hard- and software is available everywhere. The prices for Ethernet-Cards are despite their essentially higher capability on the price level from serial I/O-Cards sunk. PC-Ethernet-Cards in PCI-technology is einserseitses extremely fast and much important: thanks to DMA they can handle the data-transference in the PC in the background.
Ethernet as alternative to asynchronous interfaces is
and compatible to existing software.
Since Motorola start of 1997 the MC68302EN (a TNC3-Processor with Ethernet-controller) on the market has brought, the communication-problem is solved! It a corresponding hardware had only to be built.
With this opportunity, also the following wish-list was taken into account:
More improvements in the area battery-tension and Watchdog was considered.
Since software had to be written of course to this again, would be the project without the promise of Jimy, Dl1GJI, not realizable been. Since commercial IP-Protocoll-Stacks lie about ten-potencies outside the framework in price, this was a central decision-criterion.
The CPU MC68EN302, that was put in here, is only available since 1997. One overview offers the fig. 1.
Illustration 1: overview EN302-Expansions
This CPU offers opposite the MC68302 of the TNC3 tracing extra standard:
The total is in a 144-poliges TQFP-Casing with approximately 20x20mm with a pin-stuck out from 0.5 mm and a construction height of 1.6 mm packed. Even a small-series one must equip by means of SMD-Automat and L�tpastenschablone therefore.
An overview offers the fig. 2.
Of course, the storage was built width with 16 bits, about which maximum, to take advantage of possible Busbrandbeite. The question to a separate boat-Rome it has taken care of itself quickly, after the layout left no more place for this. That Election fell on 5-Volt Flashspeichers of AMD (2 xes 28F040 = 1 MByte), since still these in the DIL-Geh�use available is and lies in price absolutely in the framework. This DIL-Geh�use offers the possibility, during the program-development, if necessary then if necessary a Eprom-Simulator instead of the Flash-Speicher to kontaktieren. As has appeared, this was not necessary for the Inbetriebnahme however. That boat-Sector can be protected at these storages so that heads one in only the Eprom-Brenner with help of 12 volts of programming-tension possible is. In the this can consequently never appear running business.
Although the production should be with RAM exibel, has appeared also here that the application of chips small 1MBit no longer the busy conductor plate-place justifies. Standard, 2 1MBit-Chips are equipped therefore. This 1 MByte should be enough completely for applications, in which no Mailbox is required. Leaves itself over a 31-polige Direktsteckleiste up to 3 MByte RAM additionally furnish additionally. In order to prevent misunderstandings,: PC-ISA-Cards fit admitteldly also into the plug, only few survive-odd have there however!
Illustration 2: overview TNC4e
Since the previous asynchronous connection covered a SCC-channel, only 2 modems could be put. Becoming in order to avoid this without inkompatibel becomes over one of the existing mass-connections at the Modemport determined, whether here one Modem is pocketed. The modem is put, the connections of the RS232 become - Connection on an external Doppel-UART of the type 68681 switched. This UART has itself as very reliably proved, this is subject to at it that he/it at the 68000-Bus asynchronous hangs and signs with DTACK. Erfahrungsgem��s have many other UARTS weak-put or even mistakes. The second channel offers the possibility, to appraise DCF77-Impuls one. The RX-connection is therefore with on the socket of the serial interface led.
The amply known MAX doesn't become incidentally as interface-drivers... started but a bipolarer type of Analog Devive. Newest promises over the Latch-Up-Verhalten of CMOS-Drivers has moved me to a renewed comparison-test. The result was unambiguous.
As battery, a wiederau adbare Lithium-Zelle goes into action. These very temperature-constant prefabricated parts allow one oh adung with at most 3.5V over a stream-restricting Spannungsteiler. The capacity of 20mAh is enough, 4MByte RAM approximately 80 days with room-temperature or 16 days with 50� Celsius to supports.
The switch of normal-business on battery-business is on no account so trouble-free, as it seems. Here, I have fallen back on a circuit developed by me, that itself already unites 1000 in the industry-use times has proven (sees fig. 3).
Illustration 3: Battery-care
The usual supply of VCC by means of diodes doesn't suffice, since the Chip-select-Managements during the Abschaltens through forbidden areas run and data-loss can cause. Reset-Bausteine, that here a corresponding counter inserts, costs too much dilatory-time, so that faster RAM-components had to would be put in, if should be grabbed without Waitstates.
The GND-connection became in order to avoid the named difficulties undone. With it emerges in the battery-business with VCC = 0 volts a negative care-tension, during which CS-Leitung pauses on 0V. Since also the IRQ-Connection the clock of abgeh�ngt must become (otherwise pulls he/it with active Interrupt the battery empty), a TriState-Driver was put in additionally, his remaining gates the CS depend and offer additional security.
Depending of the mass happens by means of a bipolaren transistor, so that the at the beginning of-tension can become minimally 0.2V more negative than the GND-connection. The Verpolen of the npn-Transistors has no disadvantages, since an inverser basis-stream through the 1. pnp-Transistor is closed.
The dynamic fluctuations of the GND-Anschl�sse remain with 0.6V within the only 5 nSeks with the access in the tolerablem area.
In order to save Ports, a clock, that drove directly at the bus, is used here can become and consequently also byte-wisely (or here also word-wisely) is read can. Still she/it possesses an internal quartz and must balance consequently becomes. The disadvantage is the price however...
The physics of this interface should still be some unknown, so that this Topic somewhat more extensively is treated.
The original transfer-medium for Ethernet was the Koaxkabel, since itself the absorption according to cable-kind in borders held. The topology is in fig. 4 sketch.
Illustration 4: 10-Base2/5-coupling
The eldest known variation uses RG213-Kabel and is known as 10Base-5 or " Thick-Ethernet ". The cable lies with it as rope with ever one 50-Ohm Conclusion in the end in the wall. " Tap " in the truest sense of the word becomes it with a needle, that produces the contact to the inside-leader. In the clamp be the Transceiver still that receives as high-ohm-y as possible and over a steered stream-source should send. The care-tension amounts to 12V at a maximum stream of 500mA (after IEEE). This Transceiver becomes over one at most 50m tall cords with 3 verdrillten vein-mate + care over him/it 15-poligen AUI-Steckers with the Datenendeinrichtung connected.
Since the Koaxkabel with direct current becomes beaufschlagt, the care must potential-free " is which becomes difficult, as soon as one understands by it more, as showing from infinitely high (direct current) resistance.
Another standard is 10Base-2 that is known also as " Cheapernet ". Through the application of RG58-Kabel has reduced itself the Biegeradius admitteldly and that Absorption increases, but nothing changes with the principle. The simply-ness because of the cable is connected over a T-St�ck with the Transceiver, that already sits on the Ethernet-card. That PC-Ethernet-card (for 35, - DM with T-St�ck, drivers - diskette and value added tax!!) comprise everything consequently already, which to the PC-coupling one requires.
Comprises the Transceiver itself beside a hot chip (mostly DP8392, cost 25 individually approximately, - DM), a Trafo (list-price approximately 12, - DM, however nowhere available), one (insulated!) Koax-Buchse (for 7,40) and a 2W DC/DC-Wandler 5V on 9V (25, - DM, with numbers of pieces of 100 upward... ). That it of the DC/DC-Transformers on the card for 35 DM with the potential-separation HF-m�ssig maybe takes not so exactly, one only notices, if the entire network collapses when connecting. Still, the isolated BNC-Buchse puts in connection with merely stretched 500V isolation-suspense another weak-position there.
The standard offers another possibility of the coupling 10Base-T, recognizable at the 8-poligen socket that reminds at the telephone. The physical side of the connection is sketched in fig. 5.
Illustration 5: Physics of the 10-Base-T-coupling
This standard uses 2 Leitungsaares from verdrilltem bell-wire. That ungeschirmte variation is not commendable from Abstrahlungsgr�nden however. Since not also the Kontaktierung of the RJ-45 plug without matching tool simply is, the application recommends itself k�u icher cables. There are these in the Kathegorien 1 .. 5, with what the cable with Kathegorie 5 all 4 leader-pairs (for 100 MBauds) contains and the umbrella-measurement highest is. Here is the plug with a metal-collar provides that connects the umbrella with the metal-collar of the socket.
On both sides Trafoses separate the appliances with built-in Tiefpassfiltern and provide for a sufficient Symmetrierung. The Abschlusswiderst�ndes of 100 ohms sit on the primarily-side. The in PC's usual chip-sentences can these symmetrical �bertrager directly heads for, in the TNC4e, an own chip is necessary for this. For 10 The management-pairs of pin suffices MBit 1/2 and pin 3/6, that in each case 1:1 to the other Side is connected.
Since this physics still enables no bus, a so-called lifting is required to the Zusammenschalten of the single 10Base-T-Leitungen. This usually enables the connection of 8 appliances and either offers a 10Base-T line again (with turned connections) to the next lifting or one 10Base-2-connection for RG58-Kabel.
Only two appliances should be connected (for example the TNC4e with the PC-card for 35,- DM), so one can cross the vein-pair of course and comes then without Lifting from.
Although already such a lifting for 150, - DM, to receive, is, the purchase is worthwhile one Neuger�tes hardly. Since many companies switch her/its/their networks to 100MBit/s at the moment, should be the aged lifting to receive for a pocket money soon. LED - Ads for each channel simplify the diagnosis. Furthermore, a faulty puts The whole network doesn't get lamentably, since the relevant channel insulates in this case becomes.
Although appears a 10Base-2-connection profitably, he/it had on the appliance however some marked up. From experience with a Ethernet-Anschaltung in one I know industry-project moreover that in surroundings of machines with high Change-streams on the Erdleiter that 10BaseT-Variante think the Koaxkabel far is. Since not only the Abstrahlungs separate consequently with a symmetrical management also the Einstrahlfestigkeit inferior is, that turns 10Base-T in this surroundings Preference given. Another advantage is the more inferior energy-consumption (approximately 40mA with 5V) and the higher isolation-tension of typically 1,5 kVs. This seems at itself not especially high, however, to consider, it is that static discharge is unlikely because of the full-isolated cables.
An almost insurmountable problem puts the procurement of the Ethernet-spezifischen Prefabricated parts there. Under a number of pieces of 1000 pieces seems also with good will nobody, to want to deliver something. Since itself in DL for lack of demand these parts nobody on camps puts, one cannot buy her/it/them either. For 10Base-T reduced itself the problem on the Trafo, in which incidentally the necessary resistances and filters already einhgebauts are. In the context with a job-development of an industry-project with Ethernet-connection, I could a small number of pieces however these parts legally branches off.
Since was clear to me from outset that without flat mass - and VCC-connections to get not the grip on the problem of Abstrahlungen is, one became 4-lagige platinums with VCC and GND as inside-situation geroutet. The leader-leadership itself the Autorouter was left to the far biggest part.
The implementation of the XNET-Software was a matter of a Saturday-afternoon. After Jimy had completed the Ethernet-Driver within 2 weeks, the tension was big then: In the end another Saturday-afternoon the first performance-tests could run out and could show them/her/it virtually straight away also between PCs usual 200kByte/s.
He/it is suitable on the basis of his/its speed and the three radio-ports TNC4e as hardware for (X)NET. The Ethernet interface can with it on two types uses becomes. Can over Ethernet Mailboxen/WWW firstly - Servers etc at the TNC4e is connected, can more secondly TNC4e over Ethernet connected about with it the number of the radio-ports any , to increase. Fast Ethernet can the 10 MBit/s with it that on the one hand previous function of the TNC3 - HighSpeedBusses takes on TNCs among each other , to connect, on the other hand also Mailboxens can directly at the fast Ethernet is connected.
For the utilization of the TNC4e as " normal " TNC, two modes are entitled the Disposal:
(a) Hostmode: For the Power-User, the at home already a network based has, now can pack - radio of each of her/its/their PCs in the house does. A network-capable definition of a WA8DED already exists - Hostmodes. The time of the Resyncs is with it, the wrong baud rates and the lost signs finally past.
(b) AXIP: PC-FlexNet, WAMPES and numerous NOS-Derivate on different Platforms master the AXIP protocol after RFC 1226. Now can speak to a TNC4e with help of this protocol directly becomes. Becomes besides the standardm��igen i.e. for the TNC4e AXIP no particular drivers required. Since AXIP no parameter-alterations (like for example KISS) defines, it must about the KISS at least Commands is widened. The commands become as short AXIP-Frames at the TNC sent. On the basis of the length of four bytes can the TNC she/it of normal AX.25-Frames distinguishes.
With the development of the TNC4e, one kept an eye on the compatibility to the TNC3. A particular operating system requires the TNC4e admitteldly - the applications is however 1:1 to the TNC3 compatible, so that each TNC3-Software also on one TNC4e runs.
(X)NET for Win95 and Linux has already integrated an AXIP-Driver. With (X)NET on the TNC4e, the AXIP-Driver can load for Ethernet as external driver becomes. IPKISS is a type of Ethernet-Kiss-Mode, that nothing does further, as , to send out received AXIP-Frames over an AX.25 Port of the TNC4e. About not must alter existing software becomes any TNC4 - radio-port an own IP-Nummer assigned. So, it is each AXIP - capable software possibly over him/it , to base TNC4e fast Linkstreckens.
With its 20MHz processor-speed and its RISC communications processor the TNC4e offers a fast platform for future Packet-Radio applications. A scalable construction of new Digipeaters becomes possible thanks to the standardized Ethernet: Servers and Routerbausteine can be realized through simple Zusammenstecken. Another advantage of the established standard is the fair price-performance relationship of Ethernet-Komponenten. The standardized AXIP-Protokoll is supported completely by virtually all software packages for AX.25 in the meantime, so that connected the 4e at each PC-was based Digi - or Mailboxl�sung over Ethernet can become. Despite the 10 - until 100-fachen paces of the TNC4e lies her/it Price per radio-port not essentially higher than that of a TNC2H in a Token-Ring, or a RMNC-slot-card. Fills all requests the TNC4e with it, that today at a Packet-Radio-Controler is put.