Announcing availability of a QLNET driver for the Q68 (ND-Q68)

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Peter
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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Peter » Thu Jun 20, 2019 11:28 am

FrancoisLanciault wrote:Is there a problem having the three lines (3.3V, Ground and NET signal) 10 cm long ? As the length of NET cable between machines can be quite long, I don't see any issue, but I am no expert.

Ideally, you would keep the series resistor & clamp diode close to the Q68 PCB and use a GND-shielded cable for the 10 cm.


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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Dave » Thu Jun 20, 2019 2:56 pm

Before we get lost in this, I just wanted to say...

We have an exciting new feature for our Q68s. One that gives the Q68 access to floppies, microdrives and other QL expansions! Martyn Hill has adapted and written an amazing driver, and we should be focusing on the positives of that, rather than tearing down any accompanying hardware that doesn't fit our preconceived notions. I was so happy when Martyn announced his driver, because it opens up a realm of possibilities for the Q68 we didn't have before. I only designed the PCB, as open hardware that is freely available to the whole community to use or alter in any way they wish - including you, Derek - because I recently complained that it was a shame hardware developers were a bit stuck because software developers were not supporting our hardware creations with drivers. Much hardware does not exist just because of the prospect of absense of drivers. Why even develop the hardware if it will never work, because the community is too small to develop for and support it? When Martyn released this amazing new driver, I realised the opposite problem was also true, and that hardware should be quickly available.

Nobody is making anyone use the PCB, or stopping them from modifying it to their own design.


Derek_Stewart wrote:It is pity you never listed proposals before performing all the work on the PCB design.

It was based on previous work. It was already done. I didn't realise I needed to get or seek approval for my designs from anyone.

Can you please refer me to any documentation that describes the intended expansion connectors and board outlines for Q68 expansions? I have not seen any. The case was not designed to accommodate any kind of expansion, as none were anticipated.

Derek_Stewart wrote:It looks to me after an examination of the Q68 PCB, the logical way would be to orientate the expansion board perpendicular to the front panel or in line witht he expansion connector, only 2 holes would be required in the side of the case wall. The Network Sockets could be connected to the Expansion PCB by a wire link to the PCB. This would allow assembly of the Q68 to remain the same. But I am sure you will come up with all sorts of reasons why this should be done but I am reluctant to have the power switch at the side or an inline power switch on the power cable.

This is introducing non standard approach to the Q68 design.


You said, paraphrased, you do not like the power switch on the left side, because you have to "drill through the PCB guide rails and the drill bit might jam" and then said, "we should put the sockets on the left side," as if they are somehow immune to the drill bit problem.

I examined the case and PCB and made the following conclusions: I agree that putting any interface in the left side of the case is a nonsense, because it is not possible to assemble. The jacks do not have clearance to allow the Q68 PCB to slide into the case. The switch does, but only just. However, the switch is also on wires so has flexibility of motion relative to the PCB. I searched and did not find any panel mount 3.5mm sockets that also contained a switch. This is because the design of the 3.5mm jack requires a relatively short ground pin on the shaft. Even if I could, they couldn't clear the depth of the PCB guide rails combined with the enforced relationship with the power socket height. So the sockets available simply won't mount securely on the side and still allow assembly of the case.

How do you mount the sockets in the side holes then insert the PCB? You have to part-insert the PCB into the case so the power connector passes the mounting holes, then mount the two sockets, connect them to the PCB, then insert the PCB the rest of the way. They can't be soldered to the PCB or they would have a fixed relationship to the Q68 and would conflict with the case edge. If you recess them to where they would not conflict with the case when sliding the PCB in, an inserted jack would not latch and make full electrical contact.

Conclusion: side mounted anything: hard or impossible to mount, to assemble, and to obtain the parts.

I looked at the rear of the case. There is simply no clearance.

I looked at the front of the case. There is clearance along the entire top of the front of the case, except over the power socket, which lacks 2mm of clearance. I looked at placing the sockets over the SD slots, but it was problematic. I realised if the power switch were removed, and another hole drilled 10.5mm to the right, the two sockets would fit well, alongside the other thin cable that always has to be there for power and thin cable that might be there for audio. This also allowed the use of commodity parts, and the drilling of a flat, removable, replaceable plate.

The PCB does not preclude people from obtaining their own panel mount 3.5mm switched sockets and placing them anywhere they like. If they want to follow your scheme, they can. However, no such sockets are available on digikey, mouser, arrow, element14, or alibaba sites with the required 6mm threaded depth to allow securely fixing to the side wall of the case.

So, there was no need to list proposals. Once the obviously impossible options were ruled out, the only locations were "with all the other thin cables" or "in the way of the SD cards."

Take your pick :)

The logical answer is to add the expansion BELOW the Q68, which would give good clearance on all sides. The board I have designed will also fit below the Q68, if anyone desires to design a new case.

If you don't like my design, Derek, design a better one. If you don't agree with my conclusions, test your own then discover why I excluded them early on.


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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Derek_Stewart » Thu Jun 20, 2019 3:48 pm

Hi Dave,

I only meant to say that the Q68 front panel will become ugly, with lots of cables attached, I did not the fact tge power cable entered on the front panel, but this was already done.

With regards to PCB design of the expansion I only suggested that it should be orientated perpendicular to the front panel.

But it seems I am brow beaten into submission...


Regards,

Derek
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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Dave » Thu Jun 20, 2019 4:32 pm

You're welcome to produce your own design that meets your personal aesthetic requirements.

BTW: if you DID mount the 3.5mm jacks on the left side of the case, the PCB would need to start at the extension connector and head down or right, because there isn't quite enough clearance on the left side of the extension bus connector and it would conflict with the PCB. My PCB design could accommodate that by deleting the extension bus through-connector pads. It would definitely be possible to do this on the right side of the case, as there isn't a conflict with the low profile SD slots, and the JTAG port is unpopulated.


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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Derek_Stewart » Thu Jun 20, 2019 4:35 pm

Hi Dave,

Can you send me a protype board to see if this works.


Regards,

Derek
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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Dave » Sun Jun 23, 2019 5:11 pm

I will be uploading a slightly modified board later.

It fixes a bug where the termination resistors are wired incorrectly (the signal is wired to ground not the tip, and the termination resistor to the tip, not ground side of the switch. I discovered the switched 3.5mm jacks I bought have a different connector order to the unswitched ones.

It also adds .4mm extra clearance from the supercap, which is used for battery back-up. While contact doesn't present an electrical problem, the cap is quite exposed and I have to allow for the unlikely event one wasn't mounted perfectly straight.

In the mean time, please do not use the above gerbers.


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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Derek_Stewart » Fri Oct 25, 2019 4:19 pm

Hi,

I built all the current Q68 boards without an Expansion header fitted.

I am in the process of fitting an expansion header onto the Q68 board.

My preference would be to stay with most Expansion ports that have a male pin header.

Does anyone have any objections to this.


Regards,

Derek
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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Derek_Stewart » Wed Nov 06, 2019 6:34 pm

Derek_Stewart wrote:Hi,

I built all the current Q68 boards without an Expansion header fitted.

I am in the process of fitting an expansion header onto the Q68 board.

My preference would be to stay with most Expansion ports that have a male pin header.

Does anyone have any objections to this.


Since there has been no response on the preference of male or female expansion port header.

I will assume my preference of a male header is the preferred option.


Regards,

Derek
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Re: Announcing availability of a QLNET driver for the Q68 (ND-Q68)

Postby Peter » Thu Nov 07, 2019 8:28 am

Hi Derek,

many thanks for the update. One would hardly expect a question about the gender of the Q68 expansion port header here under "Software and Programming".

There was a suitable "Hardware" topic "Q68 Extension bus questions" at https://qlforum.co.uk/viewtopic.php?f=2&t=2725

How about announcing it there, and see if there is repsonse?

All the best
Peter



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