Sunday, October 15, 2017

Integrated PCB assembled and functional

I got my integrated PCB in the mail last Friday, and spent some time populating it. After fixing some bad soldering jobs and doing a bit of debugging ... it works! The only problem in the board was an incorrect wiring of the on/off switch, which is easily fixed by cutting one trace. The I2C devices enumerate properly on the mux. Here I have not yet populated it with the fancy and expensive pressure sensors, but I did install two of them temporarily to make sure that they are showing up on the bus.

The next steps are to adapt my code to the new board configuration, which should be pretty quick, and expect the 3D printed mounting components, which should come in this week.

Saturday, October 7, 2017

Modified probe design and some 3D printed parts

Pursuant to the flight test dud, I have been redesigning the innards of the probe to fit on a single PCB for reliability so that (a) I don't have to pack a bunch of barewired parts with foam to try to get them to stop rattling, which as we've seen makes them fail; and (b) I don't have a bunch of parts rattling around with a LiPo battery in the probe body.

The new probe looks like this:

The forward support and rear cap for the PCB are being 3D printed. This is how they look, below. Note how the rear cap supports the PCB yet includes a generous cutout for access to the board edge connector and switch, and to expose the on-board temperature sensor chip.