PCBWay

 Posted by  Electronics  No Responses »
Jul 192018
 

Creating hardware projects usually involves a lot of time spent creating PCB design and then even more deciding which prototype service to use. When PCBWay approached me to consider their service, all I could say is heck yeah. :)

The first thing you’ll experience ordering boards from them is a page full of options. While you can select a few simplified “deals” from main page, they will all bring you to this page for customization. And you can customize a bunch. It’s like a prototype service on steroids.

You can select number of layers (up to 14), material (including flex construction), board thickness (0.4 to 2.4 mm), copper thickness (1 to 4 oz), and surface finish (including hard gold – great for edge connectors). Yes, not all combinations are supported at the same time – for example you cannot have 14-layer aluminum board) – but there is enough choices to make you happy and/or crazy.

You can also select track/spacing (up to 4/4 mil) and hole size specification (0.2 mm) with or without plugged vias (great for BGA work). If you click on special option you can further select castellations, edge plating, impedance control, blind vias, the list goes on and on. If you need it, chances are you can order it. A more “standard” customization of solder mask and silkscreen color almost goes unnoticed.

All these options do come at price. Not only the cost of board can go into hundreds of dollars but it also makes the whole process way more complicated than what you’ll need 99% of time. Clicking on various options can get you so sidelined that you’ll forget about the most basic stuff.

For example, I managed to order all my boards without ENIG finish (immersion gold) just because I somehow missed that option. I would kill for a few simple templates with the most logical options preselected (e.g. ENIG for surface-mount soldering) and with only limited customization allowed (e.g. solder mask and silkscreen color). Yes, there are “specials” available but they still end at the same overly-complicated page.

Upload process is rather pain-less and even supports my favorite RAR format. I used the exactly same files I usually use with OSH Park and PCB:NG service without any issue. Unfortunately, there is no gerber preview here so you might be up for a surprise if something goes wrong.

As one has to define size for board during upload, I intentionally selected a smaller size for one of them. Person doing verification caught it and corrected both board size and the price. This gives me hope that any gerber errors might be caught too but note that such manual review will probably happen a few hours after the upload. This means delay for any issue not easily correctable. I would consider first uploading gerbers to OSH Park and using their awesome preview to perform a sanity check.

Combined with overly extensive customizations, lack of preview makes service much harder for hobbyist (such as myself) to use and I believe even professionals don’t care/need about most of these options on a regular basis. Even when such extensive customization is needed, I doubt one would prefer to go from scratch each and every time.

It takes a few (five in my case) days for boards to get produced but then comes the longest part – shipping. As PCBWay is in China, this means that any cheap shipping will take a while. The cheapest option actually took 2 weeks to arrive, making it slightly slower than US-based competitors. Of course, this assumes you are in States. For international customers timeline might not differ as much. Moreover, there is option for courier shipping but at a significant premium.

Once boards arrived, I found a few things in common to all – most noticeably v-groove routing for external edge. It makes board much cleaner and without any sharp edges to deal with. Boards themselves come either vacuum packed or in a baggie for the small sizes. While vacuum packing might be a bit annoying to open, it does protect the boards quite well in transport.

I immediately hated the addition of order number to the silk screen. While it seems engineer took care to place it underneath big components where it wouldn’t be visible, it’s kinda lottery if you need a really clean look (e.g. customer facing panel). If you note where their number can and cannot go on the silk screen in the comment field, I am reasonably sure they will cautious. However, such instructions are an extra step you need to remember and there is still some risk the number will be written right where you don’t want it.

Testing consisted, as usually, of hand-soldering the boards using Hakko D-888 soldering iron. As I use lead-free solder, the temperature was set to (rather low) 350 °C most of the time. All fine-pitch soldering was done by flooding all pins with solder and then wicking the extra away.

First board I got to solder was TmpUsb. It’s a small board with all SMD components and white solder mask did look awesome initially. As I went soldering, I noticed a residue forming whenever I touched the solder mask. Not only this sticky residue was ugly to see but it also stuck to the tip. As this was actually my first board with white solder mask, I am not sure if this is something common for that color or PCBWay uses a formula that’s not particularly heat resistant. In any case, not ideal for soldering iron work.

Second board was for Binarko. Not only this board has a fine-pitch component (0.2 mm TQFP-48) alongside quite a few 0603 passives but it’s intended to be press-fit mounted into the case. The good news is that fit is as close to perfect as it gets. Use of v-groove also means there are no breakout tabs to get rid of resulting in much cleaner look. Since I forgot the HASL coating, getting microcontroller aligned was a bit of challenge. Interestingly, the black solder mask handled high temperature much better than it’s white counterpart making much less mess.

Fine-pitched PIC meant I had to use solder wick a lot and that has shown another issue – it’s really easy to lift a trace. When it happened the first time I played around a bit and noted this seems to be related to the temperature. While I didn’t seem to have issues dragging 300 °C tip, at 350 °C dragging soldering tip was much more destructive.

The final board was of UsbAmps. With 0.25 mm pitch TQFP-44 package, it was a bit easier to solder. It’s green solder mask did its work well and I haven’t noticed any heat-related residue. However, sensitivity of traces to heat/dragging remained.

To conclude: If you are still using lead solder or you do reflow soldering, there are no major downfalls considering this service. While it might not be as cheap as OSH Park or PCB:NG for smaller boards (especially considering shipping is not free), it does get better with larger sizes. If board color or a bit more involved customization is necessary (think filled or buried vias), suddenly this service makes real sense. Yes, you are paying a bit (sometime quite a bit) extra but you do get something not commonly found in prototype market.

Default selection of lead HASL finish and paying extra for lead-free or ENIG is a bit of nuisance for me as I prefer poisoning my self with more fancy stuff but it’s probably not a problem for many considering the love hobbyist market still shows toward the good old 60/40.

There is quite restrictive service offered by OSH Park and PCB:NG where selection of anything other than 2 or 4 layer process is simply not possible but you get your board quickly and at a reasonable price. On the other hand there is almost infinite possibility of customization PCBWay embraces but not without the cost.

Now, only if they would stop adding their numbers to boards…

PS: I was given boards for free by PCBWay. I don’t believe that affected my review, but I believe it’s fair to disclose. :)

Unscaled Doesn’t Mean It Won’t Scale

 Posted by  Programming  No Responses »
Jul 142018
 

One application I created had to show a simple, fixed image on screen. As it’s size is fixed and no resizing is needed, one might assume following code would be sufficient:

var left = (ClientRectangle.Width - bitmap.Width) / 2;
var top = (ClientRectangle.Height - bitmap.Height) / 2;
e.Graphics.DrawImageUnscaled(bitmap, left, top);
e.Graphics.DrawRectangle(SystemPens.WindowText, top, left, bitmap.Width, bitmap.Height);

However, running this code might result in image significantly larger than the rectangle.

You see, DrawImageUnscaled will not necessarily ignore all scaling. It will attempt to preserve physical size – not size in pixels. So, if you have a screen punching above ancient 96 DPI, you will see scaling happen.

So, if you want to draw unscaled image, just use the normal DrawImage function and specify the size yourself.

Supermicro’s IPMI Firewall Rules

 Posted by  Network  No Responses »
Jul 092018
 

If your internal firewall is very restrictive or you need to expose IPMI to the outside world, you might be presented with a bit of a challenge due to quite varied port selection.

The first ports you have to allow are of course TCP 80 and 443 for web management interface. Almost all IPMI implementations have it and quite often it’s the interface with the most features. For example, Supermicro’s implementation only allows BIOS update and port number changes over web interface. This interface unfortunately stops just short of allowing console access.

To get access via IPMI tool (I use Supermicro’s IPMI View) you need to have UDP port 623 allowed through. This will allow logging into the IPMI interface and seeing machine’s status. Unfortunately, this too stops short of console access.

The key to the console (aka KVM) access is in TCP ports 3520 and 5900. These will allow you to see and type into. And only if you ever ran IPMI in nonrestrictive network would you notice something missing.

The missing piece is the menu, allowing you to mount virtual media and similar. For this you need to enable TCP port 623. This will finally allow full control over the hardware.

It’s a bit of annoyance that so many ports are needed but in general this doesn’t present the problem. Unless there are special circumstances, you shouldn’t access IPMI from the outside via port forwarding. What you should do is use VPN and then use IPMI via it.

Annotating Icons

 Posted by  Programming  No Responses »
Jul 042018
 

Placing icon in tray is usually quite straightforward. You usually just take application icon and assign it to NotifyIcon. But what if you want to add a small annotation to tray icon (e.g. small shield)?

Well, you can do something like this. Just get application icon and draw another image on it. Yes, it does require a bit of calculation to get it into the bottom right corner but nothing that a little math cannot handle.

private static Icon GetAnnotatedIcon(Bitmap annotation) {
  var icon = GetApplicationIcon();

  if (icon != null) {
    var image = icon.ToBitmap();
    if (icon != null) {
      using (var g = Graphics.FromImage(image)) {
        g.DrawImage(annotation, (int)g.VisibleClipBounds.Width - annotation.Width - 2, (int)g.VisibleClipBounds.Height - annotation.Height - 2);
        g.Flush();
      }
    }
    return Icon.FromHandle(image.GetHicon());
  }
  return null;
}

There is only one magic moment above – how to get application icon. Fortunately, a bit of P/Invoke goes a long way.

private static Icon GetApplicationIcon() {
  var hLibrary = NativeMethods.LoadLibrary(Assembly.GetEntryAssembly().Location);
  if (!hLibrary.Equals(IntPtr.Zero)) {
    var hIcon = NativeMethods.LoadImage(hLibrary, "#32512", NativeMethods.IMAGE_ICON, 20, 20, 0);
    if (!hIcon.Equals(System.IntPtr.Zero)) {
      var icon = Icon.FromHandle(hIcon);
      if (icon != null) { return icon; }
    }
  }
  return null;
}

private static class NativeMethods {
  public const UInt32 IMAGE_ICON = 1;

  [DllImport("user32.dll", CharSet = CharSet.Unicode)]
  static extern internal IntPtr LoadImage(IntPtr hInstance, String lpIconName, UInt32 uType, Int32 cxDesired, Int32 cyDesired, UInt32 fuLoad);

  [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
  static extern internal IntPtr LoadLibrary(string lpFileName);
}

And yes, this code doesn’t take DPI into account so your high-definition icon might suffer – let’s leave that for some other post. :)

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