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We built a Power over Data Line (PoDL) compliant device and power supply as part of a one-month 'sink or swim' approach to designing and testing new hardware, a

We built a Power over Data Line (PoDL) compliant device and power supply as part of a one-month 'sink or swim' approach to designing and testing new hardware, and getting to look at maturity of the 10Base-T1 ecosystem. The board was enclosed a submersible sensor node and field tested at a popular dive reef, SCUBA diving down and mounting it to the jetty. It was also a nice excuse to get some macro shots of the PCB assembly process, including some nice footage of solder paste melting and the interesting surface tension interactions. (I can't seem to get the videos to render in a format that iOS Safari will play, if anyone knows the ffmpeg incantation, please let me know, nothing I've tried has worked on my iPhone...)

fanf2 3y ago
Interesting write-up with some very nice pictures! The videos worked for me on my iPhone. Always nice to see a bit of solder reflow :-)
- killcoder 3y ago
  Turns out it might just be my phone, what a weird bug.
maaarghk 3y ago
my shell history has this in it, but it might have been for android firefox ~ `-c:v vp8 -b:v 2000k -pix_fmt yuv420p`
Timon3 3y ago
Might I suggest using an ffmpeg frontend like HandBrake? It has a bunch of presets, the Apple ones will surely work for this.
doctorpangloss 3y ago
The amount of expertise that went into this 1 month project is crazy and it's all really cool and well put together. I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." Why do sensor things at all? What is the ROI for the person who needs that stuff? I mean this in no derogatory sense, I really admire this work. But the academics who need something something hardware are either so rich they use something commercial / the paid core or so poor they'll use someone else's refuse or a grad student to do it 10x worse & 10x slower for free. Lab equipment, sensors, whatever. If it's for an industrial purpose, the ultimate consumer for hardware 2 guys can make is the government, as far as the eye can see. Like the people who have a business stake in e.g. the ocean ecosystem are fishermen, oil people, shippers, whatever, and they're only doing this because of a government regulation or threat thereof or whatever. I view government needs as worthwhile, they are a worthy customer, it's that the ROI is essentially imaginary, it's whatever the payer values government compliance and that can be infinitely large or small. My background in this is very limited, I didn't take "How to Make," I don't know how to use anything in a fablab, but in an intellectually honest way, the audience for "polished, well working gizmo with bug-free firmware" is 1,000,000x larger when it's a coffee machine than any academic or industrial purpose. Why not make "the perfect espresso machine" or "the perfect bike" or whatever? There are $3m Kickstarters for coffee machines whose #1 actual obstacle to successful execution is writing firmware. There are e-bikes that are 10x expensive or 10x crappier because ultimately it's too challenging to make a single firmware and controller to make disparate commodity parts work together cohesively. I am not at all raining on this parade, because this little blog post was so mind numbingly impressive; and I'm not saying there aren't 10,000 people toiling on dead-on-arrival consumer hardware, be it Oculus peripherals or connected emotive robots or whole divisions at Google. My question is: why? Why not, with your skills, make a thing and fucking sell it?
- CuriousCosmic 3y ago
  Not OP but > I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." You aren't meant to make no mistakes, just only make recoverable mistakes. In a lot of cases you can rely on your hardware for this. Watchdog Timers are specifically intended for this. You set up a watchdog when you deploy the device and your software has to periodically "pet" the watchdog or the system triggers some action. In practice this is used to verify that the software never gets stuck or else it triggers a recovery/restart sequence and maybe sends out an alert. The end goal shouldn't be bug free but "even with bugs it eventually recovers and keeps working unless the hardware physically dies". > Why do sensor things at all? What is the ROI for the person who needs that stuff? I mean this in no derogatory sense, I really admire this work. Once again not the OP but I could see this being useful. They are recording wave patterns on or around a reef. That could be used for modelling how reefs can buffer water conditions (ex: for the purpose of constructing man made analogues) or as part of a greater sensor suite for documenting how "weather" impacts reef ecosystems. And you would want a system you can deploy and leave unattended for long periods of time since every trip out costs money and depending on what you are specifically researching, simply returning to the site could interfere with/disrupt the experiment.
- lelanthran 3y ago
  > I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." Process, design and architecture play a larger role in the bugcount than language choice. I wrote munitions control software in C; many of the systems that would cause loss of human life were written in C for decades. The recent meme of "if it's written in C it must mean unreliable" is inaccurate - all the most reliable systems, for decades, were written in C.
  - danielheath 3y ago

fanf2 3y ago

Interesting write-up with some very nice pictures! The videos worked for me on my iPhone. Always nice to see a bit of solder reflow :-)

killcoder 3y ago
Turns out it might just be my phone, what a weird bug.

maaarghk 3y ago

my shell history has this in it, but it might have been for android firefox ~ `-c:v vp8 -b:v 2000k -pix_fmt yuv420p`

Timon3 3y ago

Might I suggest using an ffmpeg frontend like HandBrake? It has a bunch of presets, the Apple ones will surely work for this.

doctorpangloss 3y ago

The amount of expertise that went into this 1 month project is crazy and it's all really cool and well put together. I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." Why do sensor things at all? What is the ROI for the person who needs that stuff? I mean this in no derogatory sense, I really admire this work. But the academics who need something something hardware are either so rich they use something commercial / the paid core or so poor they'll use someone else's refuse or a grad student to do it 10x worse & 10x slower for free. Lab equipment, sensors, whatever. If it's for an industrial purpose, the ultimate consumer for hardware 2 guys can make is the government, as far as the eye can see. Like the people who have a business stake in e.g. the ocean ecosystem are fishermen, oil people, shippers, whatever, and they're only doing this because of a government regulation or threat thereof or whatever. I view government needs as worthwhile, they are a worthy customer, it's that the ROI is essentially imaginary, it's whatever the payer values government compliance and that can be infinitely large or small. My background in this is very limited, I didn't take "How to Make," I don't know how to use anything in a fablab, but in an intellectually honest way, the audience for "polished, well working gizmo with bug-free firmware" is 1,000,000x larger when it's a coffee machine than any academic or industrial purpose. Why not make "the perfect espresso machine" or "the perfect bike" or whatever? There are $3m Kickstarters for coffee machines whose #1 actual obstacle to successful execution is writing firmware. There are e-bikes that are 10x expensive or 10x crappier because ultimately it's too challenging to make a single firmware and controller to make disparate commodity parts work together cohesively. I am not at all raining on this parade, because this little blog post was so mind numbingly impressive; and I'm not saying there aren't 10,000 people toiling on dead-on-arrival consumer hardware, be it Oculus peripherals or connected emotive robots or whole divisions at Google. My question is: why? Why not, with your skills, make a thing and fucking sell it?

CuriousCosmic 3y ago
Not OP but > I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." You aren't meant to make no mistakes, just only make recoverable mistakes. In a lot of cases you can rely on your hardware for this. Watchdog Timers are specifically intended for this. You set up a watchdog when you deploy the device and your software has to periodically "pet" the watchdog or the system triggers some action. In practice this is used to verify that the software never gets stuck or else it triggers a recovery/restart sequence and maybe sends out an alert. The end goal shouldn't be bug free but "even with bugs it eventually recovers and keeps working unless the hardware physically dies". > Why do sensor things at all? What is the ROI for the person who needs that stuff? I mean this in no derogatory sense, I really admire this work. Once again not the OP but I could see this being useful. They are recording wave patterns on or around a reef. That could be used for modelling how reefs can buffer water conditions (ex: for the purpose of constructing man made analogues) or as part of a greater sensor suite for documenting how "weather" impacts reef ecosystems. And you would want a system you can deploy and leave unattended for long periods of time since every trip out costs money and depending on what you are specifically researching, simply returning to the site could interfere with/disrupt the experiment.
lelanthran 3y ago
> I don't comprehend how you made no mistakes on the journey after drafting the PCBs and writing drivers. From my POV as a software developer, C has so many pitfalls that it is incomprehensible to me that things will Just Work, especially in the context of something that is meant to run for a very long time and not be "restarted." Process, design and architecture play a larger role in the bugcount than language choice. I wrote munitions control software in C; many of the systems that would cause loss of human life were written in C for decades. The recent meme of "if it's written in C it must mean unreliable" is inaccurate - all the most reliable systems, for decades, were written in C.
- danielheath 3y ago