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I slimmed down the crystal traces to reduce miller effect coupling since I uploaded that picture. In your opinion is it ready to make the pcb?
 

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Discussion Starter #62
I dunno, It's kind of hard to tell just based on the PCB renders. I sat on mine for a couple weeks, and kept finding small things to improve after I thought I was done with it. Some stuff you don't notice until you give it a couple days and approach it fresh. It looks like the flood fill under the MCU isn't connecting to all the grounded pads.
 

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Standoffs are useful, but I think less convenient if you have to cut them to length, because they're difficult to hold onto while cutting them. With wood you can cut them off of a piece that's long enough to hold onto easily .

Though if you see some 3.4~3.5mm tall M3 standoffs, let me know.
Here some pictures of my implementation, you can see on the last pictures how I make it more easy to manipulate I just screwed a big standoff on the small one which give me extra grip.

This one seems close. It's hard to have the right size but you can mark the height you want on cut it roughly, and sand it until you'll get to your mark.
 

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Discussion Starter #64
Did you mark location then glue them in place individually? Or did you attach them to the PCB and glue them all at once? I think the second option would be easier to get everything aligned, but it also might be a good way to fog up a sensor or lens with CA fumes.
 

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Did you mark location then glue them in place individually? Or did you attach them to the PCB and glue them all at once? I think the second option would be easier to get everything aligned, but it also might be a good way to fog up a sensor or lens with CA fumes.
haha I attached them to the PCB and look from the bottom to correctly align the lens on the hole. I had like 3 sec to correctly align it or it would be too late :D

Better solution, if you can print the design of your PCB at the 1/1 scale with a mark at the center of your sensor, I will align it like a sewing pattern and mark the locations with a pin through the paper, you can use tape too.

Don't forget to sand a bit both part you want to glue with cyanoacrylate. (always better make some test first to get the feeling of it) If you make a mistake you will be able to unglue it easly just twist it with a pliers and resand it a bit to remove old glue.
 

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Discussion Starter #67

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i'm using kicad 6.0.0 for some reason. it grabs new kicad files from the repo every day, must be development builds or something. pcb layout editor doesn't work today, there's a bug in the right click menu, i'll try it again tomorrow or this evening when the new build comes.
 

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I honestly don't understand much what has been discussed in here but I absolutely love this kind of project....

Necessary? No

Fun project? Absolutely.

Keep it up
 

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page 96

UART0, UART1, SPI0, SMB0, CP0, CP0A,
CP1, CP1A, SYSCLK, PCA0 (CEX0-2 and
ECI), T0, T1, T2/3/4
Any port pin available for assignment by
the crossbar. This includes P0.0 – P2.3
pins which have their PnSKIP bit set to ‘0’.
The crossbar will always assign UART0
pins to P0.4 and P0.5.

the crossbar is mostly blue so I think you can, it's very flexible.

found another mistake in my pcb, the differential pair routing for usb completely screwed up.
 

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i'm using kicad 6.0.0 for some reason. it grabs new kicad files from the repo every day, must be development builds or something. pcb layout editor doesn't work today, there's a bug in the right click menu, i'll try it again tomorrow or this evening when the new build comes.
That's why I don't like KiCad, you should give it a try to design spark which is more user friendly in my opinion !

What about thermal vias in your design ?
 

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Discussion Starter #73 (Edited)
page 96

UART0, UART1, SPI0, SMB0, CP0, CP0A,
CP1, CP1A, SYSCLK, PCA0 (CEX0-2 and
ECI), T0, T1, T2/3/4
Any port pin available for assignment by
the crossbar. This includes P0.0 – P2.3
pins which have their PnSKIP bit set to ‘0’.
The crossbar will always assign UART0
pins to P0.4 and P0.5.

the crossbar is mostly blue so I think you can, it's very flexible.

found another mistake in my pcb, the differential pair routing for usb completely screwed up.
That's what I thought at first, but as far as I can tell, you can tell the chip which pins to use for the crossbar, and which peripherals you want enabled, but you can't tell it what order to assign things, it always uses the same order.

Honestly, when I think of a "crossbar" I would expect inputs to map to outputs in any order. Using that word to describe this is a bit misleading, you can't change the order at all. If I put MISO on P2.2, MOSI can only go on P2.3.
 

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>thermal via
this is the first I have heard of them. I did read a note saying 2 layer boards can carry higher current because the air cools them compared to a trace inside a 4 layer type. since i have decided to abandon rgb to simplify routing and will only use a standard luminosity 3mm led for a power up check, the heat generated will likely be small.
>you can't change the order at all
if you are worried you can use the example on page 97. it would help if you had more examples to copy off but since it is such a rare mcu that is unlikely.

kicad hasn't given me much trouble to be fair, and now that i have someone to bounce questions off i am getting adept in it. it was my decision to use development builds to maximize compatibility with obscure part libraries. by using a repository it had a lower learning curve so long as i kept updating.
 

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>thermal via
this is the first I have heard of them. I did read a note saying 2 layer boards can carry higher current because the air cools them compared to a trace inside a 4 layer type. since i have decided to abandon rgb to simplify routing and will only use a standard luminosity 3mm led for a power up check, the heat generated will likely be small.
>you can't change the order at all
if you are worried you can use the example on page 97. it would help if you had more examples to copy off but since it is such a rare mcu that is unlikely.
I noticed I had plenty on the WMO and the Zowie PCB so I include it myself on my design. For the path of it every component have a specific thermal signature so you just copy the path of each of them, then you need to connect the vias to your top and bottom ground layer. I also did the same as microsoft and put some silklayer mark on them to differentiate it from via connecting traces.

I will upload a picture of the zowie's pcb for you to see the vias pattern.

here's two link about it :

https://www.electronics-cooling.com/2004/08/thermal-vias-a-packaging-engineers-best-friend/
https://www.edn.com/electronics-blogs/the-workbench/4421218/PCB-layout-tips-for-thermal-vias
 

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> I will upload a picture of the zowie's pcb for you to see the vias pattern.
no need tbh, the pcb doesn't have to be perfect, i'm not launching a mouse company here lol. i'm just going to take my time and whenever i have all the serious concerns worked out i'll order it. I doubt anyone is going to copy it due to the learning curve. i've made a few pcbs for other projects and they all worked fine without an issue, even the handmade type. this is my first smt pcb though and the thermal problems should be much less than anything I did before. I have a local guy lined up to assemble it.
 

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I have a faulty g502 that keeps powering off here and I am wondering could i use the sensor without code mods. I have found the g502 srom.
 

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Discussion Starter #78
That's a PMW3366, right? I think qsxcv would know more about any differences.

In any case, I have boards back. A couple minor clearance issues with scroll wheel, but nothing a small washer and 30 seconds with a needle file can't fix.
 

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Indeed, 3366. I won't annoy the guy though. It's not especially important anyway. no pcbs yet here but I did receive the em11b. as I expected they are too large to fit within the case. They probably only suit a large wheel like a finalmouse. mine don't have a proper shaft, just a short round stubby one with a flat screwdriver notch at the end. they were dirt cheap though. what is that large ic with so many pins? an eprom perhaps?
I realized my pcb is also compatible with the wmo but it would take a redesign to achieve intellimouse 1.3 compatibility, which is a shape I have more interest in. I would need a huge hole in the pcb to clear the rear screw. I think I have reached the point where I have to stop feature creep though and just finish it.
 

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Discussion Starter #80 (Edited)
Indeed, 3366. I won't annoy the guy though. It's not especially important anyway. no pcbs yet here but I did receive the em11b. as I expected they are too large to fit within the case. They probably only suit a large wheel like a finalmouse. mine don't have a proper shaft, just a short round stubby one with a flat screwdriver notch at the end. they were dirt cheap though. what is that large ic with so many pins? an eprom perhaps?
I realized my pcb is also compatible with the wmo but it would take a redesign to achieve intellimouse 1.3 compatibility, which is a shape I have more interest in. I would need a huge hole in the pcb to clear the rear screw. I think I have reached the point where I have to stop feature creep though and just finish it.
The IC below the microcontroller is a non-inverting buffer used for positive feedback based hardware debouncing(edit: 74HC7541PW). It's honestly a bit overkill. You'd have to hold the switch in an indeterminant state for quite a while for there to be any advantage over just a capacitor. There is a very small potential performance benefit over using two pins on the microcontroller, because it will latch into the correct state on the first edge, you don't get the small amount of variance caused by sampling the pin during a bounce.

I believe there are also a few bus transceiver ICs that would work as a drop in replacement.
 
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