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Thread: Open source WiFi RS232 Modem

  1. #11
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    I think at that point it might be easier and faster to design something that runs off the parallel port if the primary goal is a wireless LAN solution and less of a wireless modem. At least then you have a nice TCP/IP stack like mTCP that already exists.
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  2. #12

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    Iíve been thinking about doing a parallel port WiFi adapter that emulates a PLIP server based around a CC3200 series WiFi module. It should be just as fast as one of those Xircom parallel port Ethernet adapters. (You should be able to get a few Mbps out of an EPP/ECP port.)

    The nice thing about the CC3200 series is the fact it has two MCUs onboard. One is dedicated to handling the network stack (WiFi, TCP/IP, onboard HTTP server, mDNS, etc.) and the other exclusively runs the userís code. Theyíre connected via a high speed bus internal to the module. That by itself greatly descreases overhead.

    Iím thinking implementing a PLIP server would be the best way to go, as thereís already a couple of class 1 DOS PLIP Packet Drivers available (at least one has the source available too). It would also work under Windows 9x with the Parallel Null Modem driver and the SLIP option in Dial-Up networking.

    If I would have known about your WiFi Modem project before I started work on my Serial WiFi Dongle, I most likely would have started working on a parallel port version instead. The speeds Iím seeing are on-par with yours (10KB/s), but thatís really a limitation of the serial port more than anything. This weekend Iím planning to see just how far I can push the ESP8266ís serial interface. If you could get it up to 512k or 1Mbps youíd be approaching parallel port speeds!

  3. #13

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    drdanj, does your gadget support the full set of signals? Eg. TX, RX, DCD, DSR, DTR, RTS, CTS, and for bonus points, RI. What about in bound connections?

    Tnx!

    g.
    Proud owner of 80-0007
    http://www.f15sim.com - The only one of its kind.

  4. #14
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    ESP32 would be a good choice as well.
    "Good engineers keep thick authoritative books on their shelf. Not for their own reference, but to throw at people who ask stupid questions; hoping a small fragment of knowledge will osmotically transfer with each cranial impact." - Me

  5. #15

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    Quote Originally Posted by geneb View Post
    drdanj, does your gadget support the full set of signals? Eg. TX, RX, DCD, DSR, DTR, RTS, CTS, and for bonus points, RI. What about in bound connections?

    Tnx!

    g.
    Yes, it supports inbound connections, but you can expand the firmware as you see fit, it's all open! Have a look at the code on GitHub, it's very easy to see how it's working.

    Rts/cts work as expected, the current hardware design can reroute those to dsr/dtr as appropriate, but again, if it doesn't do what you need you can add to it and mess it around to your heart's content. I think as it stands the hardware should address most situations.

    - I should add, that adding more signals will require the addition of more line drivers. As it stands the MAX3232 can deal with two incoming and two outgoing signals (i.e. tx, rx, cts, rts), driving more lines at RS232 levels will necessitate the addition of at least another one. There are a number of other GPIOs unused on the ESP12E, so it could cope with adding the additional signals.
    Last edited by drdanj; Today at 03:31 AM.

  6. #16

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    Quote Originally Posted by eeguru View Post
    ESP32 would be a good choice as well.
    Indeed, the firmware will work with it, just the schematic and pcb would need updating. People are completely free to do this and release again under the same terms very happy to help anyone who wants to try.

    d.

  7. #17

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    Yeah, you'll need to add the line drivers for sure. The DCD and DTR lines are the important bits for running inbound connections - my primary interest is putting old machines up running BBS programs. It would be nice to avoid the hassle of needing a Raspberry Pi running TCPSER.

    FYI, if you decide to make a Commodore-compatible version, you won't need line drivers at all since the user port is all TTL level.

    g.
    Proud owner of 80-0007
    http://www.f15sim.com - The only one of its kind.

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