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[T] 3.5" Screen PPI
08/09/2022 at 05:54 • 0 commentsSo I'm modelling the concept and I'm looking into what the actual dimensions of the panel is. I didn't find that, but I did find out that the 3.5" screen is probably some of the oldest OLED around.
I was wondering why the contrast ratio seemed awfully low for an OLED panel.
The 3.26" screen has the expected high contrast, but I don't think I'm going to be able to cut 6mm from the length or 3mm from the height because of how tight everything already is.
Yes, I know that this watch is going to look more like a sci-fi prop or a cyberdeck. This Hack Chat notification about the latter is partially a reason why I considered documenting this project.
The good news is that the seller of the 3.5" display also has a 3.47" display. The bad news is that it has a lower resolution.
The good news is that it has a useful feature that sounds like it could be used for AOD.
I can't find contrast ratio or model (oh wait actually it's a AMS347FF01), but I have found this little announcement article from 2011:
Also, I though 198ppi was good, but then I checked the ppi of the low resolution 1.54" screens found on earlier android watches:
A crisp resolution for this size was 320x320px:
Perhaps it was Android making things blurry on the 240px screens (similar to DPI scaling issues on Windows), but the 480p OLED would look crisp in comparison to the 360p one.
Not sure where the listing is getting 198PPI from. Both screens only get 300cd/m^2 so visibility outdoors might be questionable. Hmmm decisions...
[about 5 minutes later]
I just found out that the 360p AMOLED was used in the Nokia N8 (source), which makes me think that it was the same OLED used in the Nokia E7 which I own (because I wanted to take notes with it, but working with only 2 thumbs is slow, hence #Tetent Tiny [gd0040] ), and if that's the case then the low power mode makes sense because the Nokia E7 had an always on display and was some of the best in OLED technology I've ever seen. I heard Nokia put some coating on the screen for even deeper blacks, but citation is needed.
Ok, if a 4" screen looked fine on the E7, a 3.47" of the same resolution should look even better.
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[M][T][R] Side profile sketch
08/08/2022 at 21:53 • 0 commentsIdea 1
Currently stetching a concept idea for the project thumbnail. My first-thought idea was an L like shape, but I don't think clothing would work that well around it and I don't think the keyboard would be in a good location. This is my first sketched idea.
The screen is on the outer face of that 6mm thick section and the Tetent keyboard is in the 19mm section. Unfortunately, the entire width of the watch is way out of bounds.
Tetwin Switches
I've turned to #TeTwin Switches [gd0041] to see if I can reduce its height. Now that I know that the distance between columns needed is more like 21mm instead of 17mm, I can remove the 2mm dowels from the top of the 2 keycap sections.
I have a feeling that I'd be using M3 screws or 3mm dowels instead of 2mm due to better availability at the >35mm lengths the design calls for. Ideally, the M3s would actually be on the outside and hook the main key on both sides:
A shorter key both helps with this project and #Tetent Tiny [gd0040], as well as fitting the thumb keys next to the finger keys for all #Tetent [gd0090] projects. It seems that the tallest key is 16.95mm, so including things like the PCB, it's likely to fall in the 19-20mm range anyway.
Idea 2
So this idea includes the eliptical shape of my arm 80mm from the wrist, as well as a location for the thumb buttons. However, those thumb buttons increase the thickness of the section above the arm to 21mm and the large curve means that there isn't even 35mm of space for the screen.
Specification considerations
Keyboard
It seems that the only location a solution won't immediately fail is if the keyboard is on the top of the arm. Any other side is too thick. When my fingers are bent, the distance between them is more like 19.5mm and not 21mm. The new Tetwin design seems tolerant to such a change. Then there's the rotation of the forearm that further complicates things. Tetent having such a small window of comfortable configurations really doesn't help; perhaps the thumb column would have to be ommited since it's what's causing the ergonomic issues (just like in all Tetent projects at the moment, now that I think about it). I only need the first two:
I actually have only now realised that the keymap only calls for 4 buttons and not 5. Anyway, I think the plan is to remove the bottom two and just have 2 extra long switches. This may solve a few issues across the whole Tetent lineup since I don't have to get the thumb in a position to press a <6mm long keycap whilst not pressing the ones around it. It also greatly simplifies the mental compute, resulting in lower intent-to-keypress latency. It's also more straightforward knowing that Ctrl, Alt and Win are toggle modifiers instead of just Win being a toggle and having to do some fancy, potentially 2 handed work with Ctrl and Alt.
Screen
It seems that the side of my arm is still the optimal viewing angle for the screen and use of the keyboard. How bendable are standard OLED's anyway? Anyway, it looks like the keyboard would make the outer length >80mm so the OLED I found in the previous log is out. If the watch is going to be large, it should at least be large and sleek and without relatively thick bezels, and the 2.69 inch display would need bezels over 13mm in size.
I actually thought the bezels on the LEM-T / TICWRIS MAX were exaggerated to be small, but they are actually some very thin bezels IRL.
I've found this OLED display that I originally dismissed because it's 80.5mm in length.
The overall size of the Timespy would then be something like 84.5mm across the arm and 51mm down its thickness. The thickness should actually fit no issue, and if I have another 6mm of arm space to spare, I could go for a 3.5" screen.
I assume that the 3.5" is a portrait display and the 3.26" is a landscape one. It's slightly cheaper (£5 after VAT) , slightly larger, needs slightly fewer pixels driven and with the large thumb keys, the Timespy would likely need to be 90mm anyway for ergonomics.
Battery, motherboard, speaker and joysticks
Right, so Tetent takes up a considerable amount of space already so I'm not all that hopeful.
It turns out that a) my design has come right back to the original L shape I was thinking of and b) that there's enough space for a 18650 cell. I wanted to have a removable battery but wasn't sure how it was going to happen, so this is good news.
It seems that the joysticks used in #Tetent Turntable [gd0038] could be small enough to implement into the design.
The reason why I haven't been able to merge Tetent and Turntable into one is because the only solution I could compute involved having to rotate to get the joysticks under the fingers. I don't think the same issue would happen in this configuration.
The speaker(s) is likely to be an afterthought, but I might be able to fit these somewhere:
The motherboard is likely going to be CM4 compatible but use the CB1 I got for £9 avg since I have 4 of them and 2 have been reserved for #SecSavr Suspense [gd0105]. Even at the standard £21.60 price of the CB1, it's still cheaper than all the other options that only have half the RAM.
The thickness of the CB1 is 4mm. I'll assume the PCB is an additional millimetre.
Idea 3
Thus from the research above, this is my 3rd idea:
Computation and research time: Approx 8 hours.
Published: 04:02 @ 9th Aug
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[R] Screen Options
08/08/2022 at 16:23 • 4 commentsThe screen obtainable determines the dimensions of the watch. I want to have a screen larger than 2 inches, but it seems that any solution that exceeds 65mm in any axis would become bulky for my 50x42mm arm. The main requirement is low power consumption for an always-on-display and >=30Hz (ideally > 60) refresh .
I actually started thinking about this project again because I found this screen on AliExpress:
It's even 90Hz. Unfortunately, it's 78x67mm and there are no solutions to fit it on my wrist.
It's in the description that I found out about Memory LCD.
I looked into it and it seems like a nice e-paper display alternative. That 3.16 inch one caught my eye but I didn't look into it at the time because I had just found another OLED. It looks pretty nice, though I wonder how fast the refresh rate could be.
I believe some wireframe UI version of #enSweepen [gd0096] could work on this, as well as easily suited for digital note taking (which is the reason why #Tetent Tiny [gd0040] was started) and #Interval Provisional [gd0097]. It doesn't really matter what OS the watch runs as long as it can run these apps, but it's more streamlined on the software side if the OS can use a unified codebase like MAUI.
Moving on, this is the OLED I eventually found:
Like the first OLED, it's a MIPI device. That makes it questionable if I can drive the display since it seems MIPI documentation is a guarded secret or something. The screen should be around 54.7x41mm, so it's still a tad on the small side.
Back to the reflective LCD, I found some more data on an Alibaba listing.
A 80mm long watch (76 + 2mm bezels) might be a bit of a stretch, but everything else sounds pretty good if I can actually buy it. It doesn't look like there's much availability on the internet.
It's like they're advertising straight at me. I have also been thinking of the possibility of using this screen on #SecSavr Suspense [gd0105] along with a 5 way button. From experience using the classic 12864 3D printer controller screens and the 3Devo, I'm not a fan of the rotary encoder push button.