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Progress on a fully custom mouse.

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custom modding mouse pcb shell
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#21 ·
solder like this:

practical question for you guys... where to obtain a 3360 sensor without desoldering? not sure if pixart provides samples or stuff. maybe jkicklighter might be willing to sell a sensor without his pcb.
 
Discussion starter · #22 ·
qsxcv said:
solder like this:
https://www.youtube.com/watch?v=5uiroWBkdFY
Click to expand...
Yup, at least for components with no pads in the middle. For QFN or BGA you need hot air.
practical question for you guys... where to obtain a 3360 sensor without desoldering? not sure if pixart provides samples or stuff. maybe jkicklighter might be willing to sell a sensor without his pcb.
Click to expand...
There are a few sellers on aliexpress, but I don't know if any of them are official distributors.
 
#23 · (Edited)
I think the official european distributor is here https://www.codico.com/shop/en/pmk3360is-t2qu.html

have to buy a minimum of 5 but still not prohibitively expensive. I put off buying it until more is done, speed is not a priority.
I'll probably buy from aliexpress though, as it's just a one off, though I do have a tindie board which what appears to be a faulty sensor.

I screwed up a ps2 installing a mod chip, I just can't handle those ic packages, wish usb hid came in DIP packages, but I understand impedance would be off and weight would go up.
I was thinking of doing the em11b on flying leads like how the kone xtd encoder is done, except rather than use a cradle, solder a stiff copper wire between each mounting tab, then hinge the wire with vertical wire.

edit: here's where i'm at with the schematic.
 

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#24 ·
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Discussion starter · #25 ·
Update:

Lots of small changes. Got rid of a trace running under the SPI lines and two that were squeezing between the MCU and the sensor cutout. (got rid of the 1.9v enable, and decided to run the LED off the MCU instead of the 1.9v regulator).

Also got USB data lines to the top layer and ground either side.

Maybe an excessive amount of via stitching.

This is all probably completely unnecessary for a one off, but who knows, maybe if I end up selling these someday I'll have to comply with USB and FCC requirements.
 

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#26 ·
I received the sot-23 regulator the day after I ordered it, despite paying little for postage. tbh I regret buying those parts after I saw them, as I thought they were the largest, but soic is larger again. I think if you go for a custom mcu, you should go for an soic package, but that would be different for mass production.
 
Discussion starter · #27 ·
Yeah, SOIC is easier to solder, but I already want to make that area of the board smaller.

I suppose there's no reason to stick to single sided load for prototyping. That would free up some space for easier to solder components, or just a smaller mouse.
 
Discussion starter · #30 ·
Well, I've ordered my components. Waiting on the mouse wheel before I order the PCB, because I'll have to take some dimensions off of it. In theory everything should cost about $40~60, but with extras and tools I'm probably going to end up around $300 before I'm done.

Ordered sensors from China, two each of 3360 and 3389.
 
#31 ·
You're jumping in at the deep end, making a pcb without a working dev board prototype. It used to take 3 weeks for stuff to come from china, now it takes 3 months due to trade war or something. any idea as to why kicad won't let me attack a trace to the front of a via? back is no problem. the reason there's so many resistors is because I'm using 2 pullups per switch, and actually 4 pullups on the rotary encoder, because I wanted all the resistors to be the same size, so I seriesed some of them. resistors are sometimes handy for jumping traces anyway. I should probably have the decoupling caps closer.
For a production mouse i would prefer the ec11 to the ec10, no issue with shafts breaking or getting loose, plus you can get them in horizontal mount.
 

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Discussion starter · #32 ·
gipetto said:
You're jumping in at the deep end, making a pcb without a working dev board prototype. It used to take 3 weeks for stuff to come from china, now it takes 3 months due to trade war or something. any idea as to why kicad won't let me attack a trace to the front of a via? back is no problem. the reason there's so many resistors is because I'm using 2 pullups per switch, and actually 4 pullups on the rotary encoder, because I wanted all the resistors to be the same size, so I seriesed some of them. resistors are sometimes handy for jumping traces anyway. I should probably have the decoupling caps closer.
For a production mouse i would prefer the ec11 to the ec10, no issue with shafts breaking or getting loose, plus you can get them in horizontal mount.
Click to expand...
Not sure about the via thing, the only issue I had with that was disconnecting part of a trace, reloading the netlist, then trying to reconnect to it. It could be a clearance issue. How are you placing the vias? I place mine by pressing v while drawing a trace.

As for jumping in at the deep end, Maybe a little bit, but I'm not too scared. I've looked at the code for the dev board's HID mouse demonstration, and the chip comes with a USB bootloader. skipping the dev board just changes the order in which I need to figure things out. Besides, getting a board made is cheaper than the dev board.
 
#33 ·
ah, the v trick worked out for me. must have been a bug of some kind. It would be cool if you could pull it off though. There are usb/ps2 keyboards which use v-usb on the atmega32a which is available in 40 pin dip, very easy to solder, and backwards compatible with ps2 ports (usb can't be bitbanged I understand). apparently the latency on the software usb isn't great though.
 
#34 ·
Got it routed after a struggle, I had to go back to the start and remove the led and extra level converter for motion, only 105 vias (ouch), 9 of those under the mcu, which all the sites warn not to do. who did you hire to make the pcb? I have a company lined up but they are pricy. now that i think of it I have to go back and thicken the traces for vcc and gnd.
 

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#36 · (Edited)
I've dealt with oshpark many times, helpful site. I guess maybe it is worth paying extra for it to be fully tested as I think they do. when i was using fritzing they were the only site that would accept my orders without errors. i thought kicad would give me more flexibility. customs here is a hassle buying from outside the eu but they don't think pcbs are expensive so i have got away with it so far. everything i buy is closely scrutinized though, has to be under 22 euro or so, or I get classed as a business and get a tax audit.

edit: ordered from jlcpcb 5 full size boards for 1.79 euro to my door. hard to believe.
 
Discussion starter · #37 · (Edited)
I think I might go with OSHPark for now, mostly because of the fine pitch parts and higher temp FR4. But yeah, it's difficult to beat JLCPCB's price.

Got my goodie bag from Digikey and a mousewheel from amazon that looked like it had the right shaft and hex diameters. Gonna have to move the encoder over to about where I currently have the cable routing notch. Ordered some kydex sheet to make the shell out of, and some PTFE and UHMW tape to make feet.

Also crimped my first connector. Took me a few tries to get my first good crimp(especially getting the insulation crimps to stay aligned), but from there it was pretty straightforward. Gonna have to get some better wire strippers.
 
#38 ·
digikey has expensive shipping, but there is a cut off point after which it is free, I have had very cheap shipping from farnell for a small lot. I have found too many mistakes on my pcb, because I wasn't aware of the design rules checker in eschema. I did use it in the pcb layout app, but thought that the same feature would work just the same(nope). I just autorouted the whole thing because I didn't understand how to lay it out. I will do it all freehand next time, but I can use the pcb to practice soldering on. I would like to do a pcb case for the lulz down the road so as to have a light and cheap mouse. I don't regret learning kicad though because I want to make a pcb for a handwired mechanical keyboard I have that's playing up.
 
#39 ·
Here's an idea I had for a more reliable inexpensive scroll wheel. This is to 25mm scale diameter. you make 3 of these out of pcb to give the required thickness, then solder them together, one tooth off each time, so that there are 12 spokes instead of 4. The detents are done by a hardware debounced roller microswitch for one encoder channel and a common slot photointerrupter for the other direction channel. That way there's no bounce or backscrolling, a firm detent for each position and it won't register erraticly like the optical type usually do. the cog teeth are measured to match the roller. Do you think the idea has merit?
 

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Discussion starter · #40 · (Edited)
I think there are a few issues with it, the biggest being that with both mechanical and optical components you get the failure modes of both. If you're using a gear type thing for the detents, I think you should probably make it out of something less abrasive than PCB material. Maybe something like phenolic sheet. That can be cut by anyone with a CNC router, not just a PCB house. I'd also try different tooth profiles, to see what feels best(probably want a pointy tip instead of a plateau). As for the encoder part, I don't know how hard it is electrically, but maybe you could make a capacitive encoder, similar to what they use in digital calipers. I think that would be the most reliable option provided you want to make the encoder out of PCB material. I wonder if those capacitive touch ICs would work.

For another high reliability option, maybe replace the mechanical encoder with a ring magnet (multi pole, diametrically magnetized). Position information obtained from a couple hall effect sensors. This would have to be done in large volumes to be cost competitive, and would probably still end up slightly more expensive than the mechanical encoder. I think it would be possible to get close (under $1/mouse) if you use the same stuff they make those flexible fridge magnets out of.

As for low cost, low weight, and simplicity in use, it's hard to beat an off the shelf mechanical encoder. I think if I were to spend the time to engineer something more reliable, It would take several times longer than I would otherwise spend replacing however many mechanical encoders I would go through for the rest of my life. As a feature/selling point don't think it would let you increase the price of a mouse more than say, the ability to open a mouse without peeling the feet off.
 
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