Sunday, January 29, 2017

Memory is the second thing to go

It's said that as we age, your memory is the second thing to go. And I don't remember what the first one was...

Since I have new incentive to learn to use the KiCad electronic design suite, I thought I should start with a small project. Something worth doing, but small enough that I can focus on the tool rather than the project. Also something that wouldn't cost much to re-spin if I screwed it up.

One of the first that came to mind is a test board to drive the Noritake-Itron DS2029H Vacuum Fluorescent Display (VFD). The connections to this display are a row of flat fingers along the top edge, kinda like an integrated circuit, as you can see in this photo:

I'd just plug this thing into my solderless breadboard except for one thing: the fingers have a 2.00mm pitch, not the 2.54mm pitch of my breadboard. Bummer.

I'm weighing two options for PCBs. I could make a board that mates with these fingers and connects them to pins on 2.54mm (0.1 inch) centers. Then I could wire test circuits on a solderless breadboard. The other is a complete VFD test board supporting a PIC, a USB serial interface, and the 5V-to-36V boost regulator needed to drive the VFD anode. Right now I'm leaning toward the latter.

How does the title of this posting figure into this? Keep reading...

Thursday, January 26, 2017

Major changes in Eagle licensing

When I started to do PCB layout back in 2000, I looked at a number of CAD packages. As a hobbyist I tend to favor open-source products. First I looked at the gEDA suite but it looked like a collection of un-related tools that could be forced to work together. Then I looked at KiCad, but at the time it was lacking many essential functions. Eventually I found CadSoft's Eagle.

Like several other commercial PCB CAD packages, Eagle offered a "freeware" version intended for hobbyists. All of these are crippled in some way to prevent them being used for commercial purposes, but while most limited the number of holes or devices, Eagle limited only the size of the board to 100mm x 80mm and the number of layers to two. The project I wanted to do at the time was a very small 2-layer board but had a lot of holes, so this was a good fit. When that project appeared to be destined for commercial production I spent $50 to obtain the smallest commercial license for V4. I continued to use the freeware V4 and V5 for hobby projects for several years.

When I started the 4004 replica I immediately realized that making 2-layer 100mm x 80mm boards wouldn't work. Again I looked around at other products, but discovered that Eagle V6 offered a non-commercial hobbyist license that would give me 6 layers, 100mm x 160mm dimensions, and multiple schematic sheets of a size large enough for the 4004 schematic. That seemed to work well, so I spent the $160 to get it.

A few years back Farnell bought CadSoft. The initial V7.0 release had a wacko licensing scheme that had all the Eagle users upset. Eventually the outcry forced Farnell to return to the previous licensing scheme. I was content with my perpetual V6 hobbyist license, but decided to buy the V7 upgrade to get the bugfixes. All was good until this summer, when AutoDesk bought Eagle from Farnell. AutoDesk promised expanded investment that would bring all sorts of enhancements, and even promised a better pricing structure.

Beware of people who promise to "make things great", because it means they think what exists is bad. AutoDesk's "better pricing structure" changes the perpetual license to a subscription license, meaning that you have to keep paying or the product stops working. It's "better" because if you only need the product for a month you only have to pay for a month. But then if you want to go back to a project after the end of that month, you have to pay for another month. Of course you can pay for longer-term subscriptions and get better pricing, but when the subscription runs out, poof!

As anyone who has followed this blog knows, I'll work on a project for a weekend and then it may be weeks or months before I work on it again. A subscription license is a non-starter for me and folks like me. Further, the hobbyist license I have seems to have disappeared. For me to use Eagle V8 on my 4- or 6-layer boards I'd need to buy the "Professional" package at $65/mo or $500/yr. I have seen discussions where AutoDesk has talked about expanding the "Standard" package to 4 layers, but that wouldn't help with my 6-layer ID and ALU boards, and it'd still be $15/mo or $100/yr. That's not going to happen.

Thus my involvement with Eagle has nearly reached its end. My license for Eagle V7 has no termination date, and AutoDesk can't change that retroactively. I will continue to use Eagle for the 4004 boards, as most of them have already been started and there's no reason to change horses in mid-stream. But I won't be upgrading to V8, which means no bugfixes and no support for new OS releases.

What will I use in the future? KiCad has come a long way in the last 17 years, and it continues to improve. The PCB I'll need to make to fit into the shell of the P170-DH calculator is larger than the 100mm x 160mm limits of my Eagle hobbyist license, so I'd long planned to use KiCad for that. The changes in Eagle licensing simply means that instead of that being a one-off use I won't be going back to Eagle for future projects. Instead I'll focus on learning to use KiCad as well as I have Eagle.