29/09/2023

UPDATE: Life ;^)

Feels odd to realize that it's been 9 months since the last update, and oh boy what a fun 9 months it's been... But through all this chaos we have managed to make some special memories with the little one, memories that somehow feel that bit more special then before 🥲

One thing we quickly realised is that we have way less time on our hands (surprise surprise), as our "free" time is now either catching up on chores/admin or trying to recharge our mental batteries. But as always we have found ways to adapt to the new situation (or so we claim), whether it be by improving project workflow/tracking or outsourcing tasks where/when possible.

So in this update I want to first talk about the former, improving project workflow, specifically how I now plan to use Altium Designer when working on PCBAs. Then to finish things off, I will show some snapshots of projects I have miraculously found the time to work on :O


Altium Designer Workflow & Templates

Looking back, my PCBA design workflow was not that efficient, which I guess was not ha huge deal at the time... But now that free time is that bit harder to come by, I have tried to optimize a number of aspects, for example:

Old workflow

Revised workflow

Altium CMP creation & management

A SCH symbol & PCB footprint would be linked up in a relevant schematic library (SchLib), of which there were 12 (res, cap, IC…).

SCH symbols would typically be reused, but would be copied from one component to another. So, updating a SCH symbol used by many components was very tedious as I had to update each one manually.

PCB footprints would always be created from scratch, as I could not check if a footprint already existed until I generated it (usually via IPC Compliant Footprint Wizard).

All components are now managed by a single database library (DbLib), which I edit via Microsoft Access. This makes it very easy to link up a single SCH symbol and/or PCB footprint to many components, so creating a new component is now much quicker. 

Because everything is linked up by a database this also means if I want to update a SCH symbol or PCB footprint used by many parts, all I have to do is make a single edit and the database syncs everything up.

Lastly, PCB footprints (and their name) are created based on manufacturers recommendation (vs going direct to IPC Compliant Footprint Wizard). Making it easier to see if an existing footprint is present in the database.

Altium PRJ creation

When creating a new Altium PRJ, I would first try to find a past project that somewhat resembled what I was hoping to achieve. Then I would manually copy and modify all the project files (SCH, PCB, BOM…) & individual parameters… Inevitably missing something crucial along the way.

I now have an Altium PRJ template which automatically adds all relevant files (SCH, PCB, BOM…) when a project is created. Plus, all linked files now reference the project parameters, making it very easy to update project revisions & release datapacks.

Altium PRJ release (datapack generation)

Once a project was finalised, I would then manually go over all line items in the ActiveBOM and allocate a manufacturing part number to those that did not have one (like jelly bean resistors & capacitors that used a generic component).

With the ActiveBOM configured I would then create the project datapack (PCB FAB & ASSY files) by manually generating each output container in the OutJob. With 7 containers this meant 7 individual clicks (and that’s not including setting up the container names).

Now that all components are managed by a database library (DbLib), all components are allocated a manufacturing part number (plus 2 alternatives) during component creation. So, no more fiddling with an ActiveBOM where the MPN info would be lost between projects.

Lastly, datapack generation is now handled by the Project Releaser, which itself configures the output containers (PCB FAB, PCB ASSY, PRJ validation & snapshot…) based on project parameters. Letting me generate a datapack with the click of a single button :D

With all that said, the next step is to use the revised workflow & templates for my Prusa XL side filament sensor mod. But since Prusa have not yet shared the design files (like with the MK3S), I will have to get the printer first before I can make any major progress.


Project Snapshots

As promised, here are some snapshots of projects I have found the time to work on:

1. AR2 Barrel is nearly complete, just putting on the finishing touches (LED diffusers & shell fingers)


2. Waifu decided to hold her first DnD campaign and asked me to design and 3D print some props


3. Fortifying the work area because someone has learned how to crawl ; - ;

12/01/2023

UPDATE: Bottle Steriliser Buzzer & Work Party Costume

Feels like this year is going to be a bit of a slow one in terms of blog updates, see if you can figure out why below 🙃


Baby Bottle Steriliser Buzzer

Last year we got the Minbie Steriliser & Dryer v1, a compact baby bottle steriliser. And this year we found just how loud the piezo buzzer is... which is a bit odd considering some parents/bubs are easily woken up D: 

Luckily this one was an easily fix, just add an in-line potentiometer to adjust the volume:


Work Party Costume

Last year my work held the annual birthday party at the Melbourne Museum Science and Life Gallery, with the theme being "Night at the Museum, Moments, Figures and Natural History". For my costume I decided to go as an "alien disguised as a museum cleaner", which I showed with a rather nifty headpiece (see video below)

The costume managed to win the "Most Innovative Costume" award, which was a pleasant surprise :D

09/10/2022

PROJECT: Half-Life 2 AR2, Update #19 - Barrel Electronics



After many late nights and long train rides the AR2 Barrel electronics are complete! For those curious the electronics assembly consists of 4 PCBAs:


BARREL_MAIN-BOARD

  • The Big Boss
  • Holds various switching & linear regulators that power servo & RED/WHT/RGB LEDs
  • LED brightness/colour & servo position are controlled with PCA9685PW, which itself is controlled via I2C
  • Lastly, as this is the main gateway to other PCBAs (one of which will be over a long cable...), the board has additional filtering & protection to improve EMI & ESD performance


    BARREL_LED-CARRIER-CENTRE

    • Holds a pair of RGB LED chains for barrel glow effect
    • Interfaces to front & rear PCBAs
    • Has some really cool artwork on the silkscreen/overlay ;^)


    BARREL_LED-CARRIER-FRONT

    • Holds RGB & WHT LEDs for barrel glow & muzzle flash effect


    BARREL_LED-CARRIER-REAR

    • Holds RGB & RED LEDs for barrel & shell glow effect


    And here's how the AR2 Barrel MECH & ELEC assembly looks like:


    Deep-dive into BARREL_MAIN-BOARD PCBA

    Just like with the RECEIVER_MAIN-BOARD I want to give a quick rundown of what I am happy with and what I know could be better (you know... have I had more time). But before getting into the nitty gritty here is a cool timelapse of the board being laid out in Altium:


    The Good

    1. GOOD, Solid 0V reference plane for high energy switching zones

    All of my switching regulators and complementary EMI filters are located on the bottom side, away from the "sensitive" digital zones on top layer. ~0.2mm below the bottom layer I have a solid 0V reference plane, ensuring that the high energy current traces have a closely coupled return path (think small current loop area, translating to lower emissions)

    And for those tracks that change their reference plane (as in jump from bottom to top layer), I make sure to use a 1N stitching capacitor to assist with the return path. More on this in the BAD section


    2. GOOD, Better suited bulk capacitors (package wise)

    Previously I was using 0603 sized ceramic capacitors for decoupling, filtering, & general bulk storage. A downside of such a "small" package (depending who you ask) is that with a typical X5R/X7R dielectric the capacitance will be dependant on bias voltage (and temperature), something most manufacturers don't show in their datasheet:

    NOTE: Electrolytic & tantalum capacitors also have this behaviour, and from memory polymer versions of the two are not as impacted. But as always you need to check the datasheet to know what to expect... as you can get drastically different performance with same dielectric material

    Is this a problem? As always, it depends on the application. But here are a couple of solutions/scenarios if I wanted to stick with using a ceramic capacitors:

    1. Use a dielectric that is "independent" on bias voltage or package temperature, like C0G/NP0. This is the way to go when precision is required (say an active filter), BUT be wary that getting a C0G capacitor that is >100N is going to get expensive
    2. Use a physically larger package (1206 instead of 0603) as having more bulk material assists with bias & temperature behaviour, BUT as you can expect this is at the cost of additional board space. Luckily for me I had plenty of that, so I just upped the package size:


    3. GOOD, Better suited EMI filter

    An improvement to my previous design the EMI filter topology has been changed from pi to T. Which is more appropriate when source & load impedances are LOW (like they are here) 


    The Bad

    1. BAD, Top side tracks have a poor reference plane

    I am very happy with my 0V reference plane (bottom side tracks), but I don't have the same enthusiasm for the reference plane used by the top side tracks... as the thing is incredibly choppy:

    What does this mean? Well I can expect to see increased emissions, as the return current for each trace can no longer run directly underneath. James Pawson of Unit 3 Compliance has a really good video on this, but below are some key slides to explain the issue:

    To help this discontinuity in return path I have sprinkled as many reference plane stitching capacitors as I can across the board. But now that I think of it I should have just poured 0V on the top side and stitched it to the internal 0V reference plane with a matrix of vias, spaced to reflect the highest frequency of concern


    2. BAD, LED connector positions could be better

    Though I am quite happy with the tight layout on the bottom side, once the LED related nets make their way to the top side the trace lengths become unpleasantly long due to the connector positions. Again I can expect increased emissions due to the larger loop area D:

    An easy solution would be to move the connectors (not possible), or throw more layers at the board


    3. BAD, EM zone boundary filters could still be better

    J101 could easily have a common mode choke on all 3 data lines, as each pin has a 0V conductor next to them...

    J102, P100, & P101 do not have a filter at all... So expect worse emissions (EM noise getting out) & susceptibility (EM noise getting in) performance here


    Schematic & PCBA

    And to close it all off, here are the BARREL_MAIN-BOARD schematics:


    And the PCBAs

    10/07/2022

    UPDATE: COVID, TV Cabinet, & Half-Life 2 AR2

    COVID

    Life sure has a funny sense of humour, only last week I was having a chat with colleagues about how lucky I have been to have dodge the COVID bullet for so long... and well guess who caught the thing not long after D:

    Recovery wise things are progressing well. I got over the major flu-like symptoms relatively quickly (thanks to the vaccine and booster), and am now left with a blocked nose and a minor loss of smell


    TV Cabinet

    The waifu :3 and I have finalised our biggest (physically and workload wise) wood-working project to date, a TV cabinet. Just like with our Kitchen Shelves the plan is to fasten as many thing as possible with wood joints (vs say wood screws)

    A funny thing that did happened during the SOLIDWORKS assembly check is that we realised there may be a bit of an issue getting the thing in/out of the apartment...

    Lucky for us we realised that we can just stand the bottom cabinet upright and wedge it out of the lounge/entrance-hall bit by bit


    Half-Life 2 AR2

    So what does this all mean for the AR2? Well... we are aiming to finish the TV cabinet this year (and for a really good reason too), meaning work on the AR2 will be slow ; - ;

    BUT that does not mean I am giving up, and right now I am making some slow but steady progress on the AR2 Barrel assembly:

    25/06/2022

    PROJECT: Voice Training Buttons =^..^=

    Not long ago a mate of ours got a puppy and wanted to give "voice training" a go. For those unfamiliar, this is when you teach your pet to push a button corresponding to an activity they want to do, like in this amusing video:

    After a bit of online searching they saw that FluentPet had a rather expensive button kit, so asked us if we would be keen to give them a hand making a DIY "voice board". We said yes and decided to make a mini one for our cat with whatever spare parts remained :D

    So below is how our mini "voice board" compared to our CAD model, and for those curious how it was all wired up inside: