Tim Brodie's Build Log


#1

Hi there!

I’ve been a software developer and business consultant for a few decades now. I’m looking to add some fun and interesting hardware development to the mix.


#2

So for the past couple of weeks, I’ve engaged the free projects Shine and Blinky. It was good to work through concrete examples, and test out the tool chain for creating something. I’m still waiting for the PCBs to be delivered, and have all the parts. Decided to enroll in the Journeyman subscription as well.


#3

Welcome @tmbrodie2,
It’s pretty exciting when those first boards arrive. Looking forward to seeing how you get on and what other projects you will come up with!


#4

Thanks Steve! Looking at the 1206 packages, I’m going to need to get some magnification together to do the soldering. I’m thinking of a 1080p scope being displayed on a 27" screen. Any thoughts or recommendations?


#5

I was exactly the same at the start. I have a head band magnifier with LED light that works quite well. I quickly realised that soldering these parts is not so bad - I do try to avoid anything smaller than 0805.


#6

Good lighting source and video display lag may also be a consideration. Joe


#7

Finished up a number of sections this week. It was really good to dig in. Finished the first six sections, along with Revision Control. I feel well set up to get into the CE Header module. Got my github account set up and working. I’ve used SVN in the past, but wanted to try out GIT. I’ve installed the Tortoise GIT explorer shell extension, because I prefer how the state of the files is directly visible. There’s a nice context menu interface as well. Now things will slow down a little bit, as I’m breaching back into some less familiar territory. :slight_smile:


#8

Finished the CE Header project. Found that there were enough differences in the Teensy symbol and footprint on the git repository and what was needed according to the videos that it was a good practice to modify them. Got the PCB down to having only one small signal trace on the back ground plane.

I’m interested in comments on this layout by experienced people. Would you expect much noise from this layout where the SPI_MOSI/SPI_MISO nets cross over DEVICE_TX? Would you recommend handling this differently?


(Teensy Header PCB)


#9

I think most space is always better, but in this case, them running perpendicular to one another means the signals will couple much less than if they were parallel to one another. This also will depend upon the speed of the signals and how quickly the edge of the signal is (how fast each signal rises).


#10

So I’ve got the hardware portion of the SensorBoard project completed, with just the firmware to be written now. First attempt at soldering 0805 parts. Wow, intense focus on that. Here’s a pic of the end result.

Here’s the PCB layout I did for the above. I decided to not put any devices on the back side of the board (like the LED resistors). Took a risk to pre-select the resistors for the light sensor voltage divider based on the datasheet for the selected device as well as my rusty knowledge of Ohm’s law. Lol. Should be interesting during testing.

I decided to put the missing 4k7 pull-up resistors on the TeensyConverter board instead of on the SensorBoard with the rationale that its the more logical place to put it. If there are more than one I2C devices connected, then I’d be managing which of the devices has the pull-up. Comments?

Here’s my modified TeensyConverter board with a couple of 1/4w 4k7 resistors added so I2C should work okay – although I’ve seen others using 4k9. We’ll see.

Here’s the two married together, followed by the whole stackup.

Now to work through the development of the firmware for the Teensy. Good times!


#11

Well done Tim! See, 0805 are not so bad afterall :slight_smile: The effort on the SOICs looks good.
Since the Teensy can be programmed through the Arduino IDE, there are plenty of resources to get you going.