Overall Design

[hamishmb]

Ah excellent, I thought I might have gotten the wrong end of the stick. I'm sure it can be done in a similar way to the engineer GUI.

It will somewhat depend on the devices that we intend to use to control the minster bells, but it can be done for sure, and I can do it if I find some time.

[TerryJC]

It will somewhat depend on the devices that we intend to use to control the minster bells, but it can be done for sure, and I can do it if I find some time.

The bells and MP3 sounds will be played through the Pirate Audio Boards, which I should be able to access in much the same way as the existing devices; eg using the standard sound card interfaces:

Code: Select all

subprocess.Popen(['mpg321', '-m', '-a', 'hw:0,0', fq_path])

where 'hw:0,0' (or similar) is the sound card identity (eg of the Pirate Audio) in /dev/ and fq_path is the location of the music to be played. Starting and stopping etc is covered in the code by dedicated functions and there are other functions to skip tracks or start the Change Rings, etc.

All of the above functions will simply be called from the commands received over the network instead of from the detection of the switch events, although the timing of the chimes will be internal as it is at the moment. For example the hours and quarters are triggered by functions called from a cron schedule and striking the Quarterjack is done by a couple of GPIO Pins which are triggered from within the chimes functions.

[hamishmb]

Ah, I was more referring to whether it'll be controlled from a phone, the office PC, something else etc, but all useful info.

[TerryJC]

Most likely a phone, but anything that has a browser is possible.

[TerryJC]

Penri,

With reference to our socially distanced doorstep conversation this morning, the Jack Plugs that I bought for the audio signals inside the Equipment Case were mono, so not ideally suited to the pairs of speakers that we intend to use.

However, the existing system uses a different kind of audio connector in the Quarterjack:

Connector.png (355.31 KiB) Viewed 769 times

Hopefully you will remember it. As you can see these have five contacts and the body is brought out for screening purposes.

In the Tower, we used all five contacts:

Connector_Pinout.png (87.67 KiB) Viewed 769 times

Since the speakers are currently connected in parallel and we want to use both channels of the amplifier, we would need to use another connector for the second speaker up there, (or a different connector for the solenoids). Down in the Nave, I think that one of these would be ideal and I have one in my spares drawer.

[TerryJC]

Having reached a fairly natural break for the time being on the Tiny-TV development, I have begun to look at the detailed design of the hardware (both mechanical and electronic). In due course I will start 'Mechanical' and 'Electronic' Topics for these activities, but first I will give a high-level overview of the full system design. (There will also be a 'Software' Topic. There will be a number of aspects to this design:

• Electronic Design - This will largely as described in the first post in this Topic (see viewtopic.php?p=4438#p4438. There is little actual electronic design needed since the system will be assembled from pre-built modules, eg DC/DC Converter(s), Pis, Pirate Audio HATs, network adaptors etc. It will be necessary to breakout four GPIO Pins from the Bells Pi to trigger the solenoids in the Quarterjack. This should be possible with a small piece of Veroboard located under the Pirate Audio HAT. It may be necessary to use extra long GPIO Header Pins (see https://shop.pimoroni.com/products/male ... 7338113107 to allow the Pirate Audio HAT enough room to fit. (This technique may also be needed so that there is room for fans to be fitted.)
• Software Design - This will largely be developed using the existing code, which already provides the chimes etc at the right times and allows the music to be selected and played. Additional network software (probably sockets code from the River System) will be added so that remote control and monitoring of the functions may be performed.
• Mechanical Design - Penri has provided a standard Equipment Case to package the system into. I will produce a baseboard to screw into this the case and lay out the components to see how much spare space is available for ancillary components such as connectors etc. I anticipate doing this work in the coming couple of days, but this may take longer if the case proves too small for the job.

I had intended to start ordering Pirate Audio HATs and another Pi Zero last week, but Pimoroni's advertised Sale did not include those items (there are currently no Pi Zeros available either). I'm hoping that Pimoroni will put the Pirate Audio HATs into their Black Friday Sale. If not we'll have to pay full price. Pi Zeros become available when the Factory makes a batch.

[TerryJC]

.. (there are currently no Pi Zeros available either).

That statement wasn't actually true. When I checked the Pimoroni Website last week there were no plain-old Pi Zeros, although they did have the Pi Zero W (which we need for the Tiny-TVs). I just checked again and plain-old Pi Zeros are back in stock so I ordered one of each (to share the P&P). They still have one per customer limit, but it appears that the limit isn't one of any kind of Zero.

I'll still wait for Black Friday to see if I can get a discount on the Pirate Audio HATs because they are nearly £20 each.

[TerryJC]

Penri,

Quick question. When you talked last week about using proper connectors for the Speakers, what were your thoughts about the other connections? As mentioned earlier we can use the 5-pin DIN connectors for the speakers, but we will need to get the 12 V power in and the solenoid connections out.

Any thoughts?

[TerryJC]

Quick question. When you talked last week about using proper connectors for the Speakers, what were your thoughts about the other connections? As mentioned earlier we can use the 5-pin DIN connectors for the speakers, but we will need to get the 12 V power in and the solenoid connections out.

Penri,

I need to add to this. As well as the audio to the four speakers and the wiring to the solenoids, I will also need to get the RF to the WiFi Adaptor. Initially, when I was only looking at networking the existing system, this was just another cable to route through the grommet on the left of the Ammo Box. However, if we are going to make the Equipment Box easily maintainable then we probably want something like this: https://cpc.farnell.com/siretta/asma020 ... ug%20cable.

Also. Has the Model Town got any plastic sheet that I can use as a baseboard? The piece of plywood inside the existing system is now so full of holes that it's going to constrain the layout of the new system. I've checked what I have and the choice comes down to some fairly thick (approx 1 cm) floor panelling or a very small piece of perspex that is almost certainly too small.

[hamishmb]

NB: Is it envisioned that I would be writing the web/other interface for remote control?

I have the skills to do this (and/or can acquire them) but I may be short of time as usual. If anyone else has/knows someone who has experience with web development it may be better to ask them instead, at least as a pre-emptive measure.