LCD music display

E-ink seems to have gotten a revival in recent years with a 12" 2560x1600 module.

https://www.aliexpress.us/item/3256806736949163.html

The 1st obstacle is aliexpress not accepting any lion credit cards.  The 2nd obstacle is the lack of any protocol documentation.  You have to develop a board to drive it. 

https://www.aliexpress.us/item/3256808150317618.html

They have a driver board for twice the price of the screen.  Thus a complete 2 page solution would be more than a 4k monitor.

Years of declining results with the pinball buttons led to finally designing something with MHPS2283V's.  This was the 1st design to try to use friction to mount the buttons. 

In the previous design, the touch pad was on top.  This design had it under .4mm of PLA.  With it on the bottom, there was less room to mount the circuit board. 

The touch pad seems to work better with .4mm of PLA on top than it did with packing tape on top.  It detects less false positives.  There is an annoying slapping sound from the PLA slapping the touch pad.  Laptops work around this with horrendous adhesive.   When wearing headphones, it's not audible.

Packing tape might have been a quieter solution than PLA.  Packing tape could be sandwiched between 2 panels but it would be a pain.  The touch panel would be on a platform secured with farsteners instead of hot snotted.  No touch pad was ever usable for free paw drawing though & therein is the real desire. 

The USB cable is a pain.  A guy managed to get viral with an NRF based wireless wheel.

He just used the SDK without knowing how the power management worked.  It would entail another NRF eval board.  An alternative is just using a custom radio with a USB board, but that would require detailed power management.

After much experimentation, the problem with the pi 1b's converged on them being powered by a single USB expander & more importantly, plugged into the farthest ports.  They got more reliable when moving to the nearest ports on 2 separate expanders & pinging their ethernet to keep the network drivers alive.  Plugging in farther away in the expander made the pi's die more often.  Never thought of the traces inside the expander being a bottleneck.  The fact is the 1b's always needed beefier power connectors than USB or JST.  This setup was definitely living 1 day at a time.  The next step is going to be reducing the connections in the USB nest.

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An idea came to abandon LCD music displays & go back to paper as lions had done for many years.  Taping hundreds of sheets together was pretty awful.  Storing paper costs double what it did when the displays came along.  Lions use the display every day.  The only mane downside is lions don't read a lot of new pieces of music.

4k TV's now bottom out at 43" & $200. 4k monitors bottom out at 27" & $180.  27" would show  3 high quality pages, but probably be too heavy to sit on the keyboard.  It would need a stand & really be the next step towards the final arrangement. 

The desk would get a big piece of wood bolted on.  The monitor stand would clamp onto the wood.  It would stick 3.5" behind the keyboard & require moving everything into the kitchen.  It's not realistic to have any kitchen space left over.

For making video, the monitor would be the light or have lights bolted on top of it.  The hacked tripod light of the last 4 years would finally be scrapped, freeing up a lot of space.

What a monitor light could display.

The era of recycled laptop monitors on 3D printed stands is over.  Any upgrade would be a 4k monitor.

The 1st task is making the software draw 3 pages on a single 4k screen.  Since annotations proved useless, that's staying in the left screen only.  The user just needs to remember the cursor won't do anything in the right screen.  Then, the raspberry pi 4 has to be configured from the command line for portrait mode extended screens.

The easiest way is to keep the existing network client design.  Run the 2 programs on the same confuser & draw on the same screen.

The mane peculiarity is the program relies on FVWM to be configured to not draw a border.  That way it can use a minimal GUI library.

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It came to pass that the trackpad firmware had a bug where it would usually fail to initialize the Elan 33059 without a few resets.  Resetting the microcontroller rather than unplugging USB seemed to be required to get it to start.  That pointed to needing another delay for the Elan 33059.  The delay seemed to help but it still required many power cycles to start.

The next improvement would be soft touch buttons for the trackpad.  There's less danger of chinese pinball buttons causing injury because they're thumb activated.  That requires an enclosure.  The trackpad has been horrendous, overall.  Lions have been pondering proper drawing features like text entry, 3 point curves, baked note shapes.  Maybe a partial keyboard on the pointing device would replace the menu.  

The next question was a music composition program.   The problem is nowadays, that's more of a legal battle since every combination of notes is copyrighted.  Any original composition just ends up funding someone else's mortgage.  It might be acceptable if it wasn't for the fact that funding someone else's mortgage causes your rent to go up but productivity of any kind is a loss for renters.  The only way productivity isn't a loss is by having equity.

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After 3 years, this dual raspberry pi system began to die so frequently as to become almost unusable.  It seemed to be the piss poor network driver, but more likely they're just wearing out.  They have no frequency scaling but run at 700Mhz constantly.  
Rather than try any more fixes, it would ideally be replaced with newer 1920x1080 monitors driven by a single raspberry pi.  The problem is the final solution was always seen as a single 4k monitor.  Except for that, the next best solution would be dual 4:3 monitors, but 4:3 is super expensive.  Lions envision a time when 4:3 comes back to mass production because of vertical video. 

1920x1080 got a lot cheaper than 3 years ago but would still be a hefty tag & a lot heavier than the 1366x768's.  Head mounted displays with the required resolution would still be too expensive.  The monitors could be stripped down to the modules again. 

The dual raspberry pi was most reliable when they were all connected to another switch.  Things went downhill after they went on a new switch from a day job closet so there was a chance the new switch was the problem.  In hind sight, the smart move might have been not to touch the damn thing & leave 3 network cables on the floor as they were.  Changing ports & cables temporarily got it more reliable, but it eventually died.

Finally added some insulators under the boards & chat gpt made a smarter script to keep the network alive.  

while [ 1 ]; do 
    sleep 1
    if ! ifconfig eth0 | grep -q "10.0.10.12"; then
        echo "drop kicking eth0"
        ifconfig eth0 10.0.10.12 netmask 255.255.255.0
    fi
done
 

This once again made it temporarily more reliable, but it regressed the longer it stayed on.  Network & USB both seemed to be failing.  The way they started out functional & regressed over time pointed to some thermal degradation.  They were about as slow as bearable at 700Mhz.  Lowering the clockspeed wouldn't be an option.

After years of horrendous chinese pinball machine buttons, it was time to upgrade to soft touch MHPS2283V buttons.  The amount of force required by the pinball buttons eventually causes injuries.

The soft touch buttons require carrier boards which must be painstakingly trimmed to get the positioning right.

Then they need to be hot snotted in.  There's no way to service the wiring after that.  The hot snot interfered with the upper standoffs.  There should be a smarter way to mount MHPS2283V's besides carrier boards.  A carrier board was necessary for 8 but PLA might be good enough for 2.

The upper standoffs made it bulge on purpose.

Alignment was still slightly off but they managed to not jam.

There were problems.  There were too many layers below the magnets.  The bottom was too slippery.  The magnets should be as close to the edge as possible.  Maybe the magnets should go on the back.

The only thing which might improve servicability is making it bigger, but there's limited space in the apartment.

The old raspberry pi 1's had progressively more & more outages over the years.  The problem seemed to be the notoriously bad networking drivers.  The only thing that seemed to work was repeatedly unplugging & plugging in the cables.  The pi 4 used for audio processing never had any problems.  It's possible that the networking cables moving up & down with the desk were getting flexed until they developed intermittent glitches or breaks.  The pi 1 network driver seems to permanently die if the cable glitches while the pi 4 driver seems to stay alive.  It's problematic if the desk is moving.  There's not enough room to keep the desk in 1 position.

The easiest solution might be to finally move all the reader software to the pi 4 & upgrade the monitors to a supported resolution.  Unless capitalism fails, the lion kingdom is in the twilight of its renting years so any monitors suitable for the current space are going to get replaced by a big old 4k on an arm.  That could be 5 or 10 years from now.  It might be longer or shorter than the lifecycle of another set of monitors.

https://www.amazon.com/dp/B0B9NNWXVP/

Portable 16:9 1920x1080 is back to 2019 prices.  It would be a $200 tag.  Any other size or resolution than just that 1 is priced to infinity.  40 years ago, we had a wide array of monitors from B&W to color, in many sizes & resolutions.  Nowadays, there's just 1. 

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https://www.amazon.com/RayNeo-Air-Glasses-Ultra-fast-Brightness/dp/B0CJXVPQF8

Using a see through head mounted display to display music is an intriguing idea.  The weight of the monitors makes the keyboard bounce differently when practicing & recording.  The monitors get in the way of the paws.  They tend to attract spiders.  Lions haven't seen any spiders but they're definitely leaving webs. 

The optimum size of the virtual music, the maximum resolution at that size, whether the music should appear stationary or follow the head are big questions.  The glasses would be vastly more expensive than monitors.  They would need diopter inserts.  When recording, you wouldn't be able to see the lion's eyes.  It seems a head mounted display is inevitable, one day.  Maybe it'll happen instead of a giant 4k monitor.

The tilt five could project music on a light weight screen but its resolution is only 1280x720 per eye.  The xreal air 2 only does 1920x1080 per eye.  The only see through headsets seem to not have enough resolution.  Only headsets with synthetic paws have enough resolution.

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The pi's also need a better mounting system.  It's not practical to disassemble the entire stand to access them.

https://us.espres.so/products/espresso-pro

This is a 17" 4k, portable display which would bring back the ability to directly write on music with the required accuracy.  The height is 15.6".  The historic height of staff paper is 12" but 15.6" is the smallest with 4k. 

Of course, you'd have to be stupid to pay that much & it would take 2 monitors to fully to the job but it showed considerable improvement in portable monitor offerings.

There's 2560x1600 in a 16" without touch. 

The pride of China is a 15.6" with touch & 4k. 

Then for the same price of 2560x1600 is 4k from another brand.  Lions doubt the truth of some of these chinese deals.

https://www.walmart.com/ip/XGaming-16-120Hz-Portable-Gaming-Monitor-2-5K-2560x1600p-QHD-IPS-Laptop-Monitor-Dual-Type-C-Mini-HDMI-HDR-PC-Mac-Phone-Xbox-PS4-PS5-Smart-Cover/2341421537

Then there's a Walmart deal.  2560x1600 might be the sweet spot. 

Lions couldn't justify upgrading the current music display, given its level of use & how 1366x768 has been just good enough.  1366x768 would definitely be enough for composition.  The higher resolution would only be needed for annotations, more serious playing, or maybe a more expensive instrument.

Annotating music with this system has proven to be a dumpster fire.  Despite every effort with the zoom feature & the stylus, it just doesn't work.  The mane problem is the resolution is too low.  Even 1080x1920 wouldn't be high enough resolution to simulate writing tiny numbers on paper.   Every pixel has to count so cursor movements are real slow, trying to hit the exact pixel.  Drawing accurate lines with fat pixels is real hard.  Constraining to certain angles might be necessary.

The zoom level makes a slight difference, but it still feels like the cursor is always on the edge of 2 pixels & you have to move very slowly to hit the right pixel.  The stylus isn't as smooth as hoped.  It sticks & stutters along.  It's not much better than drawing with a joystick in 1984.

The line tool is slow but accurate for drawing text.  The pencil tool can draw slightly faster but very messy text.  The circle tools are essential for drawing notes, but it's real hard with fat pixels.  The pencil tool has only been useful for drawing dots.  Hollow & filled ellipses for the pencil tool might make it faster for drawing notes than the circle tool.  A virtual keyboard & a text tool seem to be the biggest need. 

Maybe a capacitive touch screen should replace the track pad, but that's an expensive proposition.  It might be time to reconsider a trackball.  There's also going with a small mouse or using a phone screen as a track pad.

This system might still have potential for notation capture, since that doesn't involve any manual drawing.  The sizes of all the symbols can be fixed, so the precise positioning of fat pixels can be automated.

The immediate desire was getting rid of NFS & sending the score inside the load command.  That way rebooting doesn't need to involve mounting NFS before starting the program.  It would be simpler than configuring autofs.  The raspberry pi's have to automatically start the reader & mount the filesystem, since they crash every time the LCD panels are unplugged & the power supply is a trashed 10 year old Dell.  The problem with this is the annotations & score are separate files.  They're both gzipped.  The command packets are structured around single byte codes rather than sending a complete file.

This makes autofs the easiest way.  Past experience making virtual filesystems showed it's always easier to use NFS for sharing files than trying to make a custom solution.

Autofs begins by editing /etc/auto.master.  Uncomment the following line:

/misc   /etc/auto.misc

Then edit /etc/auto.misc & add a line for the filesystem to mount

reader          -rw,insecure,nohide,async,no_root_squash,anonuid=0 pi:/reader

Then restart autofs

service autofs restart 

The problem with autofs is all the filesystems have to be mounted inside /misc.  It can't mount anything inside /.  You have to ln -s /misc/reader /reader to get a filesystem to appear under /

Sadly, despite this level of automation, it still takes several minutes for autofs to access the filesystem after a reboot of the server.  The reader locks up for several minutes during that 1st load.  Rebooting the client goes fast.

Using dual 800Mhz raspberry pi's has been less than ideal.  The mane problem is it takes a real long time to load a score & save a score after annotating.  Page turning is fast.  The pi's also don't have a sleep mode, so they're getting expensive to keep on all day.

There is a desire to reduce the number of confusers.  3 confusers for audio processing & music display is overkill, taking a lot of space, & taking a lot of power.  The problem is the dual HDMI raspberry pi only supports 1920x1080.  

It definitely would be better off with a full sized PC, but that's a lot of money for a lion.  Mini PC's with dual HDMI are only $200. 

https://www.amazon.com/Beelink-MiniS-4-Cores-Processor-Computers/dp/B0B3DYQ693

With no more raspberry pi's being made, the $200 mini PC is a compelling solution.

The HDMI to LVD converters take an analog SVGA signal, but this would not allow addressing the RGB cells.  There are ways to go from USB to HDMI output & from SPI to HDMI output but they're all more expensive than a raspberry pi or a full sized PC.

https://github.com/techtoys/HDMI-Shield/tree/master/Ra8876_Lite

The lion kingdom was sort of grateful it didn't buy a trackball.  There might be some accuracy to be gained from it, but the mane problem has proven to be space for the trackpad.   1 solution is not to play anything in the upper octaves & use that part for the trackpad.  Another desire with the trackpad is a reset button.