The Nice Asgard Project Part 3 - PCB Adventures

While I wait for some input on the motor control problem, its time to start piecing together the PCB for a prototype. This means breaking out EAGLE.

The first challenge for this is to find the right package for the processor. Easier said than done it seems. Either I'm looking in completely the wrong place or there doesn't seem to be an obvious part anywhere for the MSP430FR5739RHA40. The leaves two options, make a new part or find an existing one. The good news is this the schematics for the FRAM board is available online, meaning you can use that as your starting point, a huge bonus when it comes to the USB interface. Of course, should you want to create your own part there are plenty of guides around to get started. A good place to go, aside from element-14 of course, is Sparkfun. They provide some rather good tutorials for getting going with EAGLE, including a tutorial on create a new part.

To get going I've stuck with the basics of the existing schematic. In a moment of stupidity I may have deleted the sheets containing the power supply, time to break out the datasheet and create power supply (Currently a really messy solution that possibly won't work. Still working on the choice between USB power and running from another transformer). In the process this mistake has created some options for USB connectivity. Nothing spectacular when it comes to this project, one example being removing the USB interface for the end user and leaving it as an optional module (Smaller board, lower production cost etc). The downside is however that the programming interface disappeared. That however is a challenge for later.

Ignoring this however, its time to work on the main interfaces for the hardware. EAGLE thankfully lets you label all the connections and connect them appropriately, which saves some work with figuring out what pins are free (almost, I'm still finding one or two that I may have tried to assign when they are already taken). I guess the moral of this story is to make yourself a chart of all the pins on your controller, and make note of what they go to.

EAGLE does however have one or two minor annoyances for me, the main one being copying/pasting parts between projects and schematic files. On the occasions I'm using another file as a reference, it would be nice to be able to copy parts between sheets. Another is the lack of the ability to export a part to your library for reuse later. Small issues, but it can be a bit of a pain.