Rush jobs can be a pain. They usually come in the form of a small and simple board or a seemingly minor revision to something more substantial. The common thread is that somebody wants it right now. Normally, this means setting aside your current project and whipping out a quick spin. It’s a cumulative thing that stretches the longer term projects.
Meanwhile, there are usually some departments or people within the company that move at their own pace. You may not have the clout to jump the line for whatever it is that they do. An example of this could be having the circuit simulated for signal or power integrity. It could be just getting the symbols created by the librarian. These are the things you need to get started as early in the process as possible.
One of the top engineering departments I can recall had a process where the only way we could generate a fabrication drawing was if there was an outline drawing for that specific board’s part number that was already released to the system. It wouldn’t be enough for the mechanical engineer to provide the geometry even if it was a square with four symmetric holes or even a straight-up copy of something else.
Figure 1. Image Credit: Author - A simple outline that is predetermined is a good vehicle for design reuse.
The documentation was very automated in ways that ensured that the board would have all of the connectors, mounting holes and other touch-points exactly how they were intended. The outline and other geometry were extracted from the released outline drawing. Most other places I’ve worked at basically neglected the outline drawing itself until it was demanded by the end customer. All we typically saw during development was from a data dump by the mechanical engineer and maybe a 3D screen-capture; no docs.
All of the bureaucracy of the system meant that the designer could not possibly start and complete a project in a single day. So many times, I had to remind someone that we didn’t even have a part number in the system, let alone a completed drawing that was approved by all of the stakeholders. While it wasn’t as agile, the trade-off was that we didn’t have to respin boards because a connector was mirrored to the secondary side of the board.
I’m telling you about this because my next stop was doing Chromebook main logic cards. My first one was finally complete with its two USB type-C connectors. Based on the .emn file, I placed them on the wrong side - where they created fewer design rule issues. We were doing the final design review when my manager pointed them out.
This triggered an emergency re-spin with all of the superspeed traces getting rerouted to swap lanes and polarity of the data bus. At least there was the exact amount of space required to pull this off. It was still a lesson to learn about working without a pristine placement. Chances are, this would have been caught earlier if I had shared the placement to a wider audience before doing all of the rest of the work.
Figure 2. Image Credit: Author - Team building required for 5-on-5 Foosball might spill over to a more cohesive workforce - in theory.
For sure, it would not have happened at the previous job. In fact, someone did use the wrong half of a stacking connector pair on their schematic at one point. We’ll call him “Guy”. The result was that pin one was on the wrong side of the connector compared to the outline drawing in the document control system.
The mechanical engineer who provided the outline was reusing a standard form factor for test fixtures with the new part number. I had seen this same outline before and knew that it was correct. If I remember correctly, it was two 80-pin connectors that went on the bottom but I couldn't get them to line up the signals if they were placed where they belonged.
Guy was informed that we needed to update the connectors so that the polarity matched the drawing. He refused (!) to revisit the schematic. I did something I’d never done before; routed all of the connections except those that went to the connectors and then refused to complete the board, telling everyone who would listen.
One of the people who would listen had based his own inter-board connections on the false information provided by my EE and so he joined the chorus. To say the least, he was not happy to learn this. I had already escalated to our manager and now it went further until the director of my department and the director of Guy’s had a sit-down. After that, he finally fixed the connector polarity.
At the design review, it seemed like everyone at the table had made a suggestion without getting any traction. So, it wasn’t just me and that was actually a bit of a relief. There is always more to the story and here comes the plot-twist.
The boards came in and another episode came to light. A little back-story: Day-one, I had told Guy that we had two nets with almost the same name, the difference being TCK on one pin and CLK on the other with the rest of the net-names being a match. I pointed that out as a bullet point on the first status report. No update forthcoming. It became a topic of its own consuming the next report.
Having worked on this chip before, I knew what to expect. It seemed so apparent that it was just a typographical error that needed clean-up on the schematic. I brought it up the next time Guy was in my office. He said, “Don’t worry about it.” At that point, I was still assuming good intentions and I dropped the matter.
So, boards in-house, Guy comes over with a somewhat ashen complexion. I could tell that something was up. He asked if I knew that the clock was an open circuit. “Oh yeah, you’re right, Guy and I told you about it a few times but you told me not to worry about it so I didn’t. The clock issue was totally forgotten in the struggle with something even bigger.
Figure 3. Image Credit: Author - A similar board with the infamous stacking connector pair that brought the design to a standstill.
No blowback came my way but I think that Guy got a little bit of what we call “head-shaping”. Given this fellow’s reputation, my ECAD teammates seemed to vaporize anytime Guy had a job for us. I was stuck for the clocked up board and two more follow-on boards with him. I got through those boards by setting a boundary.
It goes like this: I’d say, “Guy, this is the fifth time I’ve told you this and I’m not going to mention it ever again." He would typically act on the ultimatum but not on the first four notifications. In that strange and tortured way, we were able to get through the rest of the projects.
Strange times call for different approaches. Guy’s manager was aware of the issues and not inclined to babysit. Adjusting to the situation was the only way forward, or so it seemed. Sometimes, we do whatever we have to do to make it all work out in the end. In terms of problem solving, one size does not fit all. Identify risks and develop a mitigation strategy. Remember: It’s not all Tetris and Connect-the-Dots.