4 ms·

There are things I would build many of if they cost $2 instead of $20. Say a medium-resolution 3D volumetric mapping of temperature and humidity in my house bec

There are things I would build many of if they cost $2 instead of $20. Say a medium-resolution 3D volumetric mapping of temperature and humidity in my house becomes reasonable at $2/node, but not at $20/node. I think scale still applies at this level, but fewer hackers are thinking in terms of swarms. There are transformative applications at scale that could be interesting even to individual hackers, but scale is its own niche, just as IoT in general is a niche.

mkl 6y ago
Interesting idea. How would you power a swarm like that?
- jwr 6y ago
  Great point :-) I don't know how to build an $2 device. Especially given that in any small device I've designed, power management always took 30-60% of board space and device cost. You reach the upper bounds if it uses a Li-Po battery. There is a big gap between powering a hobby device from a bench power supply and building an actual end-user solution. EDIT: I'm reading the answers here and it's clear I did not clearly communicate what I meant. Taping a board to a bunch of AA batteries is not an actual end-user solution. Neither is hanging a couple of boards off a bunch of wires. I was talking about products, something you might expect to pull out of a retail box and use. Those mentioning PoE clearly haven't designed a device that is powered with IEEE 802.3af-2003 :-) (I have, and I have the battle scars to prove it). PoE doesn't mean you can just connect the wires and call it a day.
  - kaetemi 6y ago
    I wonder if single twisted pair Ethernet that's being standardized with PoE might become popular for cheap sensor devices... Putting WiFi on a sensor makes no sense when you still have to run a power wire.
    - jon-wood 6y ago
      I don't know how it turned out, but a friend of mine was talking about running a DC power loop round his house alongside the AC one. The idea was that he could pull 5-12v lines off that for powering things like motion sensors, or even tablets being used as control panels, rather than having the house scattered with USB wall warts.
      - Gibbon1 6y ago
        What's potentially interesting is the 802.3bt PoE standard, power up to 55W or 90-100W. And data.
        sgt 6y ago
        What PoE switches are compatible with that right now? I would love to wire the house with that.
        Gibbon1 6y ago
        I'm not sure. Though I see a whole lot of chatter from chip makers trying to sell solutions into that market. Sounds like they have figured out you can run lighting and and other IoT stuff off it. If you think about it most current IoT stuff blows. You need power for the device. And then you're using shit like WiFi for data. And even worse shit like Bluetooth for configuration. Security is a big big problem because it's brittle and conflicts with consumers need for stuff to just work. PoE solves all of those issues.
        sgt 6y ago
        Yes, even having my CCTV cameras on PoE is such a pleasure. Just one cable to worry about.
    - fanf2 6y ago
      The single pair ethernet web pages gave me the impression that it is aimed at industrial applications - the connectors alone look like they would cost $2 https://singlepairethernet.com/en/ https://singlepairethernet.com/en/
  - michaelt 6y ago
    In a way designing a $2 device is simpler, as the low price means a low component count. Having built a Dash Button clone with an ESP8266: 1. Choose a microcontroller that will run on <3 volts, and power it directly from two AA batteries in series. You have neither the power budget nor the financial budget for anything more complicated than that. 2. Your microcontroller should spend 99.99% of its time in its lowest power sleep mode. When sleeping, the microcontroller should consume <10μA and the other, non-microcontroller circuitry should consume the same amount. These are rock-bottom power levels, expect to remove any status LEDs, USB-serial converter/in-circuit debugger chips, and even linear regulators compared to a development kit. You don't have to use an ESP8266 like I did - a more experienced guy might have chosen an MSP430 or something similar. 3. Given you can only leave sleep mode 0.01% of the time, i.e. 8 seconds per day, if it takes 1 second to connect to wifi, send a message and get an acknowledgement back, you can only do that 8 times per day. If you want to update more often, you'll need something faster to connect and send a message. This is why many smart home systems use 433MHz to a base station, rather than using wifi directly. 4. A $2 budget won't include a case until you're making fairly serious volumes. Repurpose something you were throwing out, or wrap it the circuit in electrical tape, or go over budget but declare victory as you could hit the target in larger volumes.
    - StavrosK 6y ago
      You can use ESP-NOW instead of WiFi, although I'm not sure how quickly that connects and how much power it uses. I think it's much less than WiFi, but do double-check.
    - sgt 6y ago
      4. Just encase it in a blob of hot glue!
    - twic 6y ago
      For cases, matchboxes are ~20p a go: https://www.ebay.co.uk/itm/SET-50-PLAIN-WHITE-EMPTY-MATCHBOXES-WITH-DRAWER-FOR-CRAFT-FAVOURS-ADVENT-7080-/391442753163 https://www.ebay.co.uk/itm/SET-50-PLAIN-WHITE-EMPTY-MATCHBOX... You might struggle to get an AA cell in them, though.
  - StavrosK 6y ago
    There are LoLin ESP32 boards that cost around $3 and will take a JST-SH 1S lipo connector natively (and charge the battery, IIRC).
dalbasal 6y ago
True, and I think that sitting back and thinking... we will come up with such applications. These aren't hard rules. It's a matter of extent though, not absolutes. Hobby, experimental & light-commercial applications do not often need millions of units. If they don't, the difference between a $1 & $10 controller doesn't matter in the way the difference between $10 & $100 matters... in more cases than not. Other considerations (eg the dev already knows the more expensive platform, maturity, etc.) can easily override High-volume swarm applications could change the reality. You need a nexus between low end and high volume. Swarms might be that. These aren't that common though, and "high volume and cheap" is usually a large company thing. IE, if you browse around kickstarter, most microcontroller applications fit into OP's scenario. The cost of the microcontroller is not that operative. There are undoubtedly some exceptions.

mkl 6y ago

Interesting idea. How would you power a swarm like that?

jwr 6y ago
Great point :-) I don't know how to build an $2 device. Especially given that in any small device I've designed, power management always took 30-60% of board space and device cost. You reach the upper bounds if it uses a Li-Po battery. There is a big gap between powering a hobby device from a bench power supply and building an actual end-user solution. EDIT: I'm reading the answers here and it's clear I did not clearly communicate what I meant. Taping a board to a bunch of AA batteries is not an actual end-user solution. Neither is hanging a couple of boards off a bunch of wires. I was talking about products, something you might expect to pull out of a retail box and use. Those mentioning PoE clearly haven't designed a device that is powered with IEEE 802.3af-2003 :-) (I have, and I have the battle scars to prove it). PoE doesn't mean you can just connect the wires and call it a day.
- kaetemi 6y ago
  I wonder if single twisted pair Ethernet that's being standardized with PoE might become popular for cheap sensor devices... Putting WiFi on a sensor makes no sense when you still have to run a power wire.
  - jon-wood 6y ago
    I don't know how it turned out, but a friend of mine was talking about running a DC power loop round his house alongside the AC one. The idea was that he could pull 5-12v lines off that for powering things like motion sensors, or even tablets being used as control panels, rather than having the house scattered with USB wall warts.
    - Gibbon1 6y ago
      What's potentially interesting is the 802.3bt PoE standard, power up to 55W or 90-100W. And data.
      - sgt 6y ago
        What PoE switches are compatible with that right now? I would love to wire the house with that.
        Gibbon1 6y ago
        I'm not sure. Though I see a whole lot of chatter from chip makers trying to sell solutions into that market. Sounds like they have figured out you can run lighting and and other IoT stuff off it. If you think about it most current IoT stuff blows. You need power for the device. And then you're using shit like WiFi for data. And even worse shit like Bluetooth for configuration. Security is a big big problem because it's brittle and conflicts with consumers need for stuff to just work. PoE solves all of those issues.
        sgt 6y ago
        Yes, even having my CCTV cameras on PoE is such a pleasure. Just one cable to worry about.
  - fanf2 6y ago
    The single pair ethernet web pages gave me the impression that it is aimed at industrial applications - the connectors alone look like they would cost $2 https://singlepairethernet.com/en/ https://singlepairethernet.com/en/
- michaelt 6y ago
  In a way designing a $2 device is simpler, as the low price means a low component count. Having built a Dash Button clone with an ESP8266: 1. Choose a microcontroller that will run on <3 volts, and power it directly from two AA batteries in series. You have neither the power budget nor the financial budget for anything more complicated than that. 2. Your microcontroller should spend 99.99% of its time in its lowest power sleep mode. When sleeping, the microcontroller should consume <10μA and the other, non-microcontroller circuitry should consume the same amount. These are rock-bottom power levels, expect to remove any status LEDs, USB-serial converter/in-circuit debugger chips, and even linear regulators compared to a development kit. You don't have to use an ESP8266 like I did - a more experienced guy might have chosen an MSP430 or something similar. 3. Given you can only leave sleep mode 0.01% of the time, i.e. 8 seconds per day, if it takes 1 second to connect to wifi, send a message and get an acknowledgement back, you can only do that 8 times per day. If you want to update more often, you'll need something faster to connect and send a message. This is why many smart home systems use 433MHz to a base station, rather than using wifi directly. 4. A $2 budget won't include a case until you're making fairly serious volumes. Repurpose something you were throwing out, or wrap it the circuit in electrical tape, or go over budget but declare victory as you could hit the target in larger volumes.
  - StavrosK 6y ago
    You can use ESP-NOW instead of WiFi, although I'm not sure how quickly that connects and how much power it uses. I think it's much less than WiFi, but do double-check.
  - sgt 6y ago
    4. Just encase it in a blob of hot glue!
  - twic 6y ago
    For cases, matchboxes are ~20p a go: https://www.ebay.co.uk/itm/SET-50-PLAIN-WHITE-EMPTY-MATCHBOXES-WITH-DRAWER-FOR-CRAFT-FAVOURS-ADVENT-7080-/391442753163 https://www.ebay.co.uk/itm/SET-50-PLAIN-WHITE-EMPTY-MATCHBOX... You might struggle to get an AA cell in them, though.
- StavrosK 6y ago
  There are LoLin ESP32 boards that cost around $3 and will take a JST-SH 1S lipo connector natively (and charge the battery, IIRC).

dalbasal 6y ago

True, and I think that sitting back and thinking... we will come up with such applications. These aren't hard rules. It's a matter of extent though, not absolutes. Hobby, experimental & light-commercial applications do not often need millions of units. If they don't, the difference between a $1 & $10 controller doesn't matter in the way the difference between $10 & $100 matters... in more cases than not. Other considerations (eg the dev already knows the more expensive platform, maturity, etc.) can easily override High-volume swarm applications could change the reality. You need a nexus between low end and high volume. Swarms might be that. These aren't that common though, and "high volume and cheap" is usually a large company thing. IE, if you browse around kickstarter, most microcontroller applications fit into OP's scenario. The cost of the microcontroller is not that operative. There are undoubtedly some exceptions.