Sample Checks Out + Waiting…

Got the samples last week. I ought to make a video, but I have a final exam coming up very soon… Instead I spent a few minutes inspecting the board and testing the functions. Except plating was done in silver (which got promptly corrected), everything looks good! 

The color-corrected PCBs are already made. I believe they should be done with assembly this week as well. Now I am just sitting and waiting for the *rest of the order*

New Roof in the Air

Guys, don’t worry. This is just something I have queued up for the next year. My focus is still 100% on the current groupbuy for Miuni32. There is so much fun to be had working with you all in the r/mk community. I just need to let it out there. Otherwise, I’d be lying to y’all :).

Anyways, let me talk about keyboard roof for a minute. I have been using two keyboard roofs (one for my Realforce 104u and one for my HHKB Pro2) from GarbageCollection.co.kr in Korea since the summer.

Back then they didn’t have international shipping, so there were a few things to figure out with the good fellas over at GarbageCollection. Overall though, it was a more positive experience than I anticipated: over the top packaging, very swift customer support, and top-notch quality.

The only downside was the shipping cost considering the price of the product.  Hence this groupbuy came was born. Together with GarbageCollection, I will be focusing on reducing the shipping cost for US / Canada. The roof itself isn’t expensive, but the overseas shipping (from Korea where the roof will be made) normally costs just as much. We can reduce the shipping significantly by bundling the orders together.

For now, take a look at a few videos I made below:

GB Update: Miuni32 PCB is in the wrong color…

Discussion over at r/bigtuna

Hello everyone, the gist is that PCBWay.com has run tests and result look good. They also have shipped off a few boards for me to for further testing. So we are getting close!

There is a bad news here though – the surface finish was not done in Purple + Gold Immersion. Instead, it was done in Lead-Free HASL (Purple + silver color combo). So I am talking to them on getting this issue addressed. This is a setback, there is no nice way to put this =(. This is a simple aesthetic issue, but I want to get this done right for you. So even though it will cost me extra, I must own up to it. The components are available and ready over at PCBWay.com. So only the PCBs have to be remade. Normally it takes 4-5 days.

This prolonged delay is quite frustrating, but I sincerely appreciate your patience!

Miuni32 GB2 Delivery Estimation

PCBWay.com is estimating the assembly to complete on November 26th. They usually are convservative on their estimate in my experience, so let’s hope that I can send the orders out earlier.

The PCB fabrication is almost 100% complete at the moment, so I should *better* get the samples in a week or so.

I am so sorry for the delays everyone. Please bear with me. It is getting there!

Final Design Submitted!

I tried to make the behind-the-scenes action as seamless, and smooth as possible. Unfortunately, the group buy #2 has been delayed. Only now I have submitted the finalized version of design files, after going back and forth with PCBWay.com over the last few weeks. 

There are several reasons for this delay:

  • Initially, I was going to submit the design for manufacturing with only the minimal changes (artwork, stabilizer hole adjustment). As you know, I have added ESD protection chips (1 for USB D+/- (ESD122DMYR) and 1 for VBUS (TPD1E10B06)). I should have given this change in the electrical design much more foresight, as well as time. 
  • The price of $40 ($35 with coupon) does not give me a wiggle room for mistakes. Unlike the first group buy which ran last year, this price is significantly discounted. The logic for the discount was that the design was tried-and-tested. It was supposed to be as easy as clicking the “order” button. Unfortunately, I got ambitious and decided to improve the design as mentioned above. This means I must tread very carefully, as I have a very tight budget.
  • I have moved to a new place (yet again). Around this time last year, I was also in the middle of moving which caused a delay. Hopefully, this pattern does not hold up in the future ;).
  • Courage! I checked the changes multiple times. I hope I can say I have overdone it. But, to be frank, every change I make on the board makes me very nervous.

I must thank every participant for the patience. I apologize for infrequent updates. Let me try to be more transparent at least until the board ships this month.

The Drill Hole Problem

Before: Very little PCB between stabilizer hole and the board edge
After: Stabilizer hole extended beyond the PCB

I was expected to receive the prototype of Miuni32 Group Buy 2 more than a week ago. It never materialized in part due to an issue with the location of the stabilizer drill holes. The adjusted location leaves very little space between the bottom of the hole and the edge of the board. This was not a problem with manufacturing. But looking at the sample photos I just lost confidence and I felt like it could become a durability issue very easily.  So I decided to extend the hole (as a slot) to eliminate durability issue altogether. This should be the last change for this revision! Fingers crossed!

Miuni32 GB2 Delivery Status (Delayed)

Hello everyone, originally Miuni32 GB2 was estimated to ship this month, but it is looking less and less likely to be able to ship Miuni32 GB2 orders this month. Actually, at this time it is physically impossible to ship them out this month! The supposed small changes in Miuni32 are taking longer than I had anticipated to get verified. The changes include better ESD protection, some artwork update, and adjustment of the stabilizer mount holes. Albeit small, changes are changes and I can’t skip steps. Otherwise, I will get in trouble :). I am so sorry that it is delayed. The current projected date is next month (November 2018). Please hang tight! Thank you 🙂

Adding ESD Protection on Miuni32

ATmega32u4 reference does not delve into the details of ESD protection in the USB circuitry. It merely mentions this:

Although TVS chip is simple to apply, I can’t be too careful since there is more than one type. And since ESD is something I can’t readily test on my own, I must make sure the choices are effective. Searching on StackOverflow led me to a few useful posts. This one discusses how 2 TVS diodes have the exact same SOT-23 IC packaging, but functionally very different (one is unidirectional while the other is bi-directional). To be honest I am still not clear on when to use which. I think the gist is that bidirectional TVS chips are used for data lines (such as USB D+ and D-), and unidirectional ones are used for DC circuit.

My 1st choice is TPD1E10B06 from TI:

As you can see, it is a dead simple part. It is standard 0402 package, bi-directional and can easily be reworked if needed to. The only downside is that I need 2 of these… and that it actually doesn’t support USB 2.0.

My 2nd choice is the following, found in this ESD guide from TI:

The ESD122 is a small bi-directional 2 channel ESD protection diode. The price is right and it is very simple to use. The packaging is 3X2SON, which is difficult to work with hands, but luckily I don’t plan to do that.

3rd choice is the most expensive, but the most simple solution CGA-MLC from Bourns:

This comes in 0402 / 0603 package. Dead simple, but pricey especially when I need a pair of these on every Miuni32.

Miuni32 Rev.2 Status

The original estimated shipping of Miuni32 quoted in Group Buy #2 was this month. Unfortunately, we are past the first week of October already and I am still a few weeks away from receiving a few samples. I would love to skip this sampling process altogether, but because of the few changes I made, I would like to tread carefully. Things I have to verify include changes I have made
(let’s call this Rev.2)  to the original Miuni32 PCB design include:

  • ESD protection on the USB circuit
  • Improved 2U stabilizer location (Plate still compatible with Rev.1)
  • Update the logo and other miscellaneous graphics on the board 

I should be receiving a few sample boards again in 2 weeks. If all checks out then, I should receive the rest of the order towards the end of the month. Fingers crossed!