More soldering, and an updated procedure

I jumped the gun a little when I soldered the wires between the first two boards. I had the foresight to solder in the Arduino socket before soldering the board-to-board wires, but I should have also soldered the wires for the LCD of the downstream board before connecting the boards together. The board-to-board wires cover up the solder points for the LCD wires, so for the board I already did, I have to either unsolder the board-to-board wires or bend them enough to allow access.

So the new procedure is:

  1. Install two adjacent boards to the control panel. The downstream board should have nothing soldered to it.
  2. Measure, cut and strip the board-to-board wires.
  3. Remove the downstream board from the control panel.
  4. Solder the Arduino sockets to the downstream board.
  5. Reinstall the downstream board to the control panel.
  6. Add wires to the LCD and attach a positive wire to the button LED. Measure, cut, strip and tin these wires.
  7. Remove the boards from the control panel.
  8. Solder the LCD and LED wires to the downstream board.
  9. Solder the board-to-board wires.

It may seem inefficient to remove the board, add the sockets, and reinstall the board instead of just soldering the sockets and the LCD-LED wires to the board at the same time. But I want the sockets on there when I measure out the LED/LCD wires so that I have a stronger visual cue of where the Arduino will be, and I should be less likely to cut those wires too short.

In order for step 6 to work, the control panel needs to be assembled with the buttons and LCDs in place. So I reassembled the control panel and connected all the wires for the joysticks and buttons. Then I attached the LCD/LED wiring for the first circuit board, and added the Arduino socket for that board.

Then, before moving on to adding the LED/LCD wires for the second board, I added the wires that run from the relays to the first board.

That doesn’t look as clean as the ribbon I had there before, but it’s more robust and durable. I may spend some time at some point making the bends in the wires more uniform, but for now I will focus on getting the rest of it wired up.

Wires Arrived. Back to soldering.

My set of wires arrived today. I wanted to get 9 different colors, but only 7 different colors were in stock when I ordered them, so I will make do with that.

Because I am using solid core wires, I want to make them the exact length that is needed to connect adjacent boards. To accomplish that, I came up with the following procedure:

  1. Attach two adjacent boards to the control panel. The downstream board will not have the Arduino sockets soldered to it yet.
  2. Measure, cut, and strip each of the wires that connect the two boards.
  3. Remove the two boards from the control panel
  4. Solder the Arduino sockets into the downstream board
  5. Solder the wires between the boards
  6. Reinstall the two boards to the control panel to ensure the wiring accommodates the board placement
  7. Check all connections for continuity

Here is a series of photos of the process:

Here is a detailed description of Step 2 from above:

  1. Strip one end of a wire
  2. Bend the stripped portion 90°
  3. Place the stripped portion into the appropriate hole on the downstream board
  4. Cut the wire a little past the hole on the upstream board
  5. Use a utility knife to mark where to strip the cut end of the wire
  6. Strip the cut end
  7. Bend the newly stripped end 90°
  8. Place the wire into the boards and move on to the next one

In the previous image, you can see why I wanted 9 colors. I wanted unique colors for all of the switched inputs. But instead I’m just using blue and white twice.

New PCBs

Since I was ordering 5 new PCBs to replace the ones I had already tried soldering, I decided to take the opportunity to update the PCB specs and then just replace all of them. Here is a side-by-side comparison of the order images from PCBWay. (once I have the new PCBs I will also post side-by-side photos).

The changes are:

  • Traces are 0.4 mm wide instead of 0.2 mm (not accurately represented in the above low-res image)
  • Mounting holes have been increased in diameter to 3 mm
  • Solder pads for wires have been increased from 1.6 mm wide to 2 mm wide
  • Wire holes have been increased from 0.6 mm to 1 mm
  • Default REF** labels on mounting holes and solder pad have been removed/updated
  • Solder pads for wires are now labeled according to what they connect to
  • Board is slightly longer and slightly wider to accommodate larger mounting holes
  • Arduino is positioned closer to the top of the board, also to accommodate larger mounting holes
  • Wire holes are closer to the Arduino to make room for useful labels

The larger mounting holes mean that I won’t have to drill them out to fit the screws I have, as I did with the first batch.

The larger wire holes will accommodate up to 20 AWG wire (technically 19 AWG, but nobody makes that). I had ordered some 22 AWG wire before deciding to update the boards. I will probably order some 20 AWG wire and just use the 22 AWG for something else.

I was careful to keep the centers of the mounting holes (relative to each other) the same as before so that I can still use the standoffs as they are currently on the control panel. However, the old boards were pretty close to each other, so the extra width of the new boards might make that impossible. Worst case, I will have to buy more hardboard, remove all the components from the current control panel bottom layer (including the glued-down SD holders) and recreate that layer with the new hardboard. I really hope it doesn’t come to that!

Wiring issues

Finally getting back to the project after over four months. I had soldered the wires to the first four boards, but had run into some issues with wires breaking. I repaired them as best I could, but I decided it would be wise to do some continuity tests before proceeding.

The good news is that I didn’t find any connections that weren’t supposed to be there (no cross-pin solder mistakes). The bad news is that there were several broken connections. I tried repairing them, and was successful with a couple, but in the end I couldn’t get them all connected properly. Here is what it looks like:

I have decided to try using single-strand wires instead of the stranded wires I have been using. I think that will reduce the risk of breakage. I’ll probably also order more circuit boards rather than attempting to desolder the four pictured here.

So, I’m back to waiting for parts (I can get back to it as soon as I have the wires, even if the new boards aren’t in. I’ll just start with the other boards I already have.)

Board placement and wiring begins

So far I have only soldered the pins to 8 of the 20 arduinos. In the meantime, I drilled the holes for the standoffs for the circuit boards, and installed the standoffs. I don’t have any photos from those steps, because I was filming it with the intent of making another time-lapse video. But the footage was pretty disappointing, so I’m not doing that.

The process for drilling the holes was as follows: I placed the circuit boards where I wanted them, and used a sharpie to mark the locations of the holes. I put both control panel layers together and held them in place by installing a couple of the controller buttons. Then I drilled all the holes with a bit wide enough for the threaded part of the standoff. Then I separated the two layers and re-drilled all the holes in the top layer to 1/4” to accommodate the nut for the standoff.

I don’t know how it happened, but for some of the boards, the holes did not line up.

But as long as each board has at least two screws securing it, I am happy with it. Most of the boards did line up in all four holes.

As seen in the previous photo, I also started soldering the headers to the circuit boards in between getting all the standoffs installed. I have since removed the other boards and also soldered on he headers. Here is a picture with some arduinos plugged in:

I have also soldered the control and power wires to the first board, and wired them in to the relays. I completely redid the relay setup because it was kind of ugly the first time.

For reference, here is the old, ugly relay wiring:

Arduinos have arrived – let the soldering begin

I received my new batch of 20 Arduinos. So I’ll be spending some time soldering the pins into them.

As before, I’m using my prototype breadboard to hold the pins (and to provide a little bit of heat dissipation). If I don’t solder the 90-degree comm pins on first, I can set up 4 Arduinos at a time for soldering.

Here are the first four, all soldered up (minus the comm pins on three of them)

Circuit board placement

Before laying out where the circuit boards will be mounted, I had to find a way to safely turn the control panel board over without losing or breaking the LCDs. I couldn’t just remove them since I glued the SD extenders to them and then glued the extenders to the panel. I decided to try taping a piece of paper over the LCDs to keep them in place. It seems to have worked well enough.

For the placement, I wanted each circuit board as close as possible to the LCD it would be controlling. This worked out better on the bottom row, because there is more room and there are only four buttons to worry about. Here is the placement I have for now:

Here I have added some lines connecting each circuit board to the LCD it will control. This is roughly where the wires will go.

Then I added blue lines to represent the control and power wires that will come from the relay bank and go to all the boards.

The next step is to mark all the holes for the circuit board standoffs and start drilling!

Circuit boards have arrived

This stack of boards was delivered today.

Here is a photo of a single board that shows the layout pretty well:

The connectors next to pins D8, D9, D10, D11, D12, and D13 will have wires soldered to the LCD. There are two connections connected to the A0 pin. One of these will go to the LIT pin on the LCD, and the other will go to the positive side of the LED inside the button.
The two connectors on the right near the 5V pin will provide power to the LCD. The two columns on the left side of the board will be used for daisy-chaining the boards together. One column will have wires soldered to the previous board in the chain, and the other column will have wires connected to the next board in the chain. You can see from the traces on the board that these are also connected to the power for the Arduino and the seven input pins.

I have not received the new set of Arduinos, but I wanted to check that the Arduino footprint I found online was accurate. And it was: