A hardware-based USB 2.0 monitor & trigger platform, controlled from Python

Sep 06, 2019

Project update 4 of 6

Manufacturing Prep

by Colin O'Flynn

One of our final topics is getting things ready for manufacturing. This step will be the last step before starting to order the printed circuit assemblies (PCA). Lately we’ve been updating the PCB, checking enclosure assembly, and preparing other required documentation.

PCB Tweaks

There are a few minor PCB tweaks we wanted to add in. In particular, we added some series resistors on most of the external digital I/O connections (including ChipWhisperer connections). We need to confirm the values are OK here and may yet tweak that a little for best signal integrity. We also added some length-matching on the "spare" digital I/O port:

This digital I/O port can be used to support additional PHY’s, and in case anything has higher-speed timing we didn’t want to cause too many issues. In theory we can do some length tuning in the FPGA I/O blocks, but we had PCB space in this case so just did it physically.

We also built up our latest PCB and ensured it fit OK in the enclosure, which you can see below:

More Phys

While it won’t be part of this Crowd Supply campaign, we did a brief block diagram design for a 10/100 Ethernet PHY front-end that would fit onto that header to ensure we had enough I/O. This is one example of how this device could end up using the same trigger & sniffing logic for other protocols. Because it’s open-source, you can add these PHYs yourself if it’s something unique to your situation.

In this example, two back-to-back 10/100 PHY chips are used. This is preferred over just passive sniffing of the Ethernet traffic, since it helps us understand the data flow direction. The cost of the additional PHY + Ethernet magnetics is minimal. Here, a Microchip KSZ8721 is used as an example, as it also supports the "back to back" connection mode.

Enclosure Orders

To speed up delivery, we had ordered qty 25 of the machined enclosures already. These have arrived and fit OK - the previous photo is using one of these "production" enclosures. Knowing they will work OK, we’ll be ordering the remaining stock needed for our first run.

BOM, Final Quoting and Ordering

With the end in sight of this campaign, we’ve started to look at our production plans. We’ll be ordering the final PCAs this week or next week to keep on track for our delivery plans.

We’ll be working on some manufacturing documentation, along with requirements like exterior labels and ordering the accessory parts (cables, etc.) we will need to deliver.

From there, expect the next updates to include more details of the actual production & delivery timeline! Thanks for supporting this campaign and helping us launch this product!

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