Expansion serial card?

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Peter
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Re: Expansion serial card?

Post by Peter »

Nasta wrote:it is possible to use a single SPI interface with multiple devices, it becomes more and more difficult if the devices are very different.
Also for identical devices, separate SPI interfaces are important in case of different drivers. For example, think of copying from a QLWA formatted SDHC card to a Quibide formatted card, if one driver is built into SMSQ/E and the other one is separate. This is one reason why the Q68 has separate interfaces for both card sockets. Of course it also increases copying speed.
Nasta wrote:I cannot over-emphasize the importance of hardware handshaking.
Then the Q68 will disappoint you here. I did not have enough FPGA pins for more than RX and TX. Also I didn't want to use one of the bloated existing UART IP cores, so I went for a simple, efficient implementation with 16 Bytes FIFO. My thought was: Better no handshake at all ,than a not 100% reliable handshake. On the positive side, the Q68 RS-232 transceiver is one of the few, which truly support 460kbps.
Nasta wrote:Final note - most USB to serial adapters are capable of a few high bit rates, [...]
I also believed that, until I really tried. I found very few >460 kbps rated adaptors capable of true 230kbps. Try transfering continuos long streams, even with hardware handshake, and you will see.


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Dave
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Re: Expansion serial card?

Post by Dave »

I think my approach is pretty simple: find *something* that can work, test it and see if it provides the utility I am looking for, then just go to Nasta to ask what the best way to improve this problem is. I like the idea of using something Minerva recognizes as a serial port because there's a lot of driver work already done around that which doesn't apply easily to a parallel interfaced part. Since Wiznet has parallel, serial, I2C and SPI parts, this is a cheap'n'easy way for me to go investigate the possibilities and behavior of wiznet's system.

If it can do what we want, the design/method of connecting a wiznet chip can be improved massively later ;)

Well, that was my thinking. But if you're volunteering, Nasta, well I would not be one to say no. :)


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Dave
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Re: Expansion serial card?

Post by Dave »

It's been my frustration that there haven't been any good, easy to implement TCP/IP solutions to add ethernet to a QL-style system without hugely overburdening the QL CPU OR being heavily dependent on the QL's poor inbuilt serial.

Functional ethernet is an important keystone. Anyone should be able to actually get their hands on one that isn't mysteriously locked up for years and years because the developer is too busy, insecure about their work, or doesn't want to take the risk.

This is one thing we need to get done and out there.


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Peter
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Re: Expansion serial card?

Post by Peter »

Wouldn't it make sense to use the CP2200 which is also on the Q68, so two systems are the same? That should at least increase the likelihood, even if there never is a promise when you are in a small hobbyist scene with only about one or two active driver developers left.

The Motorola style 8 Bit bus interface of that 5V tolerant chip could in the end turn out easier than serialized interfacing.

If you don't want to wait for a release of QLwIP - which I can understand - there are simple portable stacks like uIP that already support the CP2200. uIP is known to run on weaker CPUs than a 68SEC000.


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Dave
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Re: Expansion serial card?

Post by Dave »

I don't plan to use the CP2200. It's not a bad choice, but there are better ones now. I'd rather go uphill from scratch with a hardware TCP/IP stack than fumble around with that slow old thing. A TCP/IP offload engine is the way to go. That way all we need to port is the SSL/TLS library.


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XorA
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Re: Expansion serial card?

Post by XorA »

Dave wrote:That way all we need to port is the SSL/TLS library.
Now that is the bit you genuinely want to offload to another CPU on 68000/68020 based machine. Even raw 68000 runs tcp/ip fine. SSL however takes a lot of CPU crunching. Doesn't really become what I would call usable until you start using 68060. (based on experience with my Amigas)


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Dave
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Re: Expansion serial card?

Post by Dave »

Well, wiznet does have a SSL/TLS offload engine coming up. ;)

Silicon Labs got nothing. I occasionally contract for them. They. Got. Nothing.

Frankly my solution would be to do mild obscure encryption of data, then use a proxy modern machine to do the SSL. That said, the WiFi card they do has an encryption engine too, I think. I'll have to read up - not sure how it could do WPA2 unless it did.


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Peter
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Re: Expansion serial card?

Post by Peter »

For QLwIP I have a nice email client, but of course no SSL. Nowadays I can not even connect to my main email account, because the provider no longer offers the standard ports.
That's really an issue, and I see no easy way out for native QL hardware.

Once you start offloading things to an external CPU which is faster than the native one, you can ask yourself why not emulate the whole QL and save all the effort.

For me, the point of QL hardware tinkering is to run things on QL side.


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Re: Expansion serial card?

Post by Nasta »

Peter wrote: Also for identical devices, separate SPI interfaces are important in case of different drivers. For example, think of copying from a QLWA formatted SDHC card to a Qubide formatted card, if one driver is built into SMSQ/E and the other one is separate. This is one reason why the Q68 has separate interfaces for both card sockets. Of course it also increases copying speed.
True, and in fact you also need to make the SPI at least a little clever (buffered) which than makes the whole issue of multiplexing even worse. So, one more argument for multiple SPI implementation, but then this is not simple. FPGA time for sure.


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Re: Expansion serial card?

Post by Timbucus »

I have been toying with the idea of looking at adding a Raspberry Pi Zero W to various retro machines to add modern comms.

There is a thread elsewhere on here about hacking the Microdrive interface to connect up some systems which faded out but seemed interesting - that is one solution that could also be used by Spectrum Interface 1 owners as well increasing the userbase, but might need more electronics and a bit of fiddling with the Microdrive drivers.

It also occurs to me that something could be done with the cartridge slot on the QL. The Pi could then also perhaps add USB mouse for people who don't have one and or even USB memory stick access. The standard I/O header on the PI I'm sure could be made to trigger some form of memory mapped access with a suitable comms protocol to drive functions and perhaps a buffer or a few support chips for bank address selection.

This started when I was looking at adding a mouse to my QL and couldn't find my serial mouse anywhere - and of course struggling to use the basic QL serial ports for comms - most frustrating that the Serial port on my main PC steadfastly refuses to TX anything out, works fine to receive at 9600 baud from the QL. We shouldn't always suspect the retro hardware is at fault...

This sort of approach will also allow some future-proofing as the PI looks to be here to stay and there is a very large dev base and support on that side. Which could be more standardised for the retro community to use, with each interest area only having to develop their sides interface. That will be cheaper and more likely to be produced in larger quantities so that it can be made available for longer.

I am no electronic whiz so I planned on sacrificing something else than the QL with my first evil experiments and before you say I have already begin experiments behind the ethics committee's back; my Oric 1 was dead when I took it out of the box honest.

I would appreciate peoples opinions - perhaps it would help on the original query as the PI has SPI and RS232 (TTL so needs a MAX232) etc?

Timbucus


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