4 ms·

Power is really one of the weaknesses of the rpi family (I'm quite excited for the new pico 2 for exactly this reason - it seems like they're finally making it

by dgacmu 2y ago

Power is really one of the weaknesses of the rpi family (I'm quite excited for the new pico 2 for exactly this reason - it seems like they're finally making it easy to enter a relatively deep sleep without external hardware). I built some cameras for an application like this using a Google Coral mini, whose camera is not nearly as good as the HQ cam, unfortunately, but it supports a built in suspend + wake from onboard RTC that is very easy to use and perfect for a periodic camera app - while still having enough oomph and 2GB of memory to handle a high resolution image. (You can physically hook an HQ camera up but the software pipeline doesn't exist to manage it on the coral AFAIK.) The Rpi ecosystem is a lot more mature and (sorry, friends) I trust the future availability of rpi more than I trust Google to keep delivering the coral line, but it really underscored how helpful good power support in the hw was. (Ironically, we ended up outsourcing the next version of these cameras to a firm that built them using an rpi and we just threw in a much larger battery to compensate. Which means I have a stack of 100 unopened coral dev minis + cameras looking for either good ideas or to sell to someone. Oops.)

cgearhart 2y ago
Interesting, I’ve always run pis from wall power. Is the pi hardware incapable of similar power optimizations to coral, or is this a problem of a lack of software support for power management on pi? (I assume from your mention of external hardware to manage power that it’s not just a software issue.)
- dgacmu 2y ago
  I'm really mixing two things and wasn't very clear about it. The pico can kinda deep sleep but it requires an external wakeup trigger. It can't deep sleep from its own clock. Even so its deep sleep is pretty high power compared to most embedded chips. The zero (w) and zero 2 w don't have the equivalent of suspend-to-ram with a low sleep current. I'm not sure if that's a limitation of the SOC or the driver or both, but rpi was fairly clear it wasn't in the cards: https://github.com/raspberrypi/linux/issues/1281 https://github.com/raspberrypi/linux/issues/1281
- rcxdude 2y ago
  I'm pretty sure it's the hardware. The SOCs they use in the mainline pi products are generally targeted at applications which aren't battery powered, so they don't focus on fast sleep support and similar power optimisations (which make the system design much more complex). Unfortunately if you want that you generally need to go with phone SOCs which are generally incredibly NDA-bound, very hard to buy even if you're as big as the rpi company, and have short availability windows which runs counter to requirements of large parts of the SBC market segment.
- michaelt 2y ago
  A typical battery-powered IoT device like the Ring video doorbell will last ~2 months on a ~6000mAh ~3.3v battery. An average power draw of about 14 milliwatts. This is quite low - a power LED can use more than 14 milliwatts. Of course some products have power consumption even lower than that, right down to the tens-of-microwatts level. Meanwhile a raspberry pi, when idle, consumes ~3 watts [1]. That's 200x more than the video doorbell. Getting the power consumption down requires (a) that your hardware draws very little power when it's in sleep mode, and (b) that it spends as much time as possible in that sleep mode. Hardware and software have to work together to achieve this, and the software changes can be extensive. [1] https://www.jeffgeerling.com/blog/2024/new-2gb-pi-5-has-33-smaller-die-30-idle-power-savings https://www.jeffgeerling.com/blog/2024/new-2gb-pi-5-has-33-s...
brk 2y ago
Out of curiosity what are you doing that can’t be done with an OTS camera these days?
- dgacmu 2y ago
  Dual cameras at 90deg to each other with lightweight onboard ml to decide capture / no capture + geotargeted higher frame rate captures for regions of interest. In a housing that can handle hard impacts from brush and off-road use (we take pictures of pasture). A lot of the video solutions have much worse image quality than a still camera operating at 1fps to 1/20 fps; you can stick a quite good camera on an rpi. It's quite likely we could COTS this but there was no interest from vendors when we wanted to start with 200 of them. So we went with a custom solution. (We are https://enriched.ag https://enriched.ag -- if you scroll down you can see our overly-heavy-metal but quite tough camera unit. Some day it will be injection molded instead...)
  - brk 2y ago
    I will contact you, I may be able to help with a better solution. This is something I do a lot of.
    - dgacmu 2y ago
      Please do, I'd love to learn. We just completed a run of our latest version so we're a ways from thinking about a new design, but it would be helpful to know know what I should be thinking about for our roadmap. dave.andersen at Gmail is probably my easiest address.
KeplerBoy 2y ago
Isn't the Coral line already dead/discontinued? The site (coral.ai) seems to have been last updated in 2021 and it says Copyright 2020. Oh god, just searched for "google coral twitter" looking for an official twitter presence of the project and the second hit was a tweet of yours looking to sell your 100 excess boards.
- michaelt 2y ago
  Well, they haven't announced it's dead. In the electronics industry, even 30-year-old microcontrollers often have pin- and software-compatible replacements available to this day. So just because something has long been surpassed, doesn't mean it becomes unavailable. The electronics industry also has an orderly process for discontinuing parts, where customers are given advanced notice and a chance to place one last order if they want to stock up. This process hasn't been started for the Coral accelerators. With all that said - it's pretty clear that Google has lost interest in the product. When you're making hundreds of billions of dollars from ads, who's got the time for a product line that's bringing less than 0.1% of that? So personally I wouldn't base a new product on Coral today.
  - Aherontas 2y ago
    It is really common for Google to delete projects out of the blue. So don't be surprised that they haven't much updates.
- dgacmu 2y ago
  I haven't seen anything official indicating it's discontinued, and they've released a few updated libraries, but there certainly seems to be very little momentum and I'm skeptical about its future. I think some friends have still bought the USB accelerator version of it to use with the frigate DVR, though. Not a good sign when offers to sell old ones feature prominently in the search results. :) It's a shame. They're actually really quite nice boards. I may have to sell them from the startup to my academic self and use them for some project or another if nobody wants them - but I don't really want to teach a machine vision course.
shrubble 2y ago
Curious if you have looked at the BeagleBone hardware with its PRU devices for low-power operation; they can stay awake while the system sleeps.

by dgacmu 2y ago

cgearhart 2y ago

Interesting, I’ve always run pis from wall power. Is the pi hardware incapable of similar power optimizations to coral, or is this a problem of a lack of software support for power management on pi? (I assume from your mention of external hardware to manage power that it’s not just a software issue.)

dgacmu 2y ago
I'm really mixing two things and wasn't very clear about it. The pico can kinda deep sleep but it requires an external wakeup trigger. It can't deep sleep from its own clock. Even so its deep sleep is pretty high power compared to most embedded chips. The zero (w) and zero 2 w don't have the equivalent of suspend-to-ram with a low sleep current. I'm not sure if that's a limitation of the SOC or the driver or both, but rpi was fairly clear it wasn't in the cards: https://github.com/raspberrypi/linux/issues/1281 https://github.com/raspberrypi/linux/issues/1281
rcxdude 2y ago
I'm pretty sure it's the hardware. The SOCs they use in the mainline pi products are generally targeted at applications which aren't battery powered, so they don't focus on fast sleep support and similar power optimisations (which make the system design much more complex). Unfortunately if you want that you generally need to go with phone SOCs which are generally incredibly NDA-bound, very hard to buy even if you're as big as the rpi company, and have short availability windows which runs counter to requirements of large parts of the SBC market segment.
michaelt 2y ago
A typical battery-powered IoT device like the Ring video doorbell will last ~2 months on a ~6000mAh ~3.3v battery. An average power draw of about 14 milliwatts. This is quite low - a power LED can use more than 14 milliwatts. Of course some products have power consumption even lower than that, right down to the tens-of-microwatts level. Meanwhile a raspberry pi, when idle, consumes ~3 watts [1]. That's 200x more than the video doorbell. Getting the power consumption down requires (a) that your hardware draws very little power when it's in sleep mode, and (b) that it spends as much time as possible in that sleep mode. Hardware and software have to work together to achieve this, and the software changes can be extensive. [1] https://www.jeffgeerling.com/blog/2024/new-2gb-pi-5-has-33-smaller-die-30-idle-power-savings https://www.jeffgeerling.com/blog/2024/new-2gb-pi-5-has-33-s...

brk 2y ago

Out of curiosity what are you doing that can’t be done with an OTS camera these days?

dgacmu 2y ago
Dual cameras at 90deg to each other with lightweight onboard ml to decide capture / no capture + geotargeted higher frame rate captures for regions of interest. In a housing that can handle hard impacts from brush and off-road use (we take pictures of pasture). A lot of the video solutions have much worse image quality than a still camera operating at 1fps to 1/20 fps; you can stick a quite good camera on an rpi. It's quite likely we could COTS this but there was no interest from vendors when we wanted to start with 200 of them. So we went with a custom solution. (We are https://enriched.ag https://enriched.ag -- if you scroll down you can see our overly-heavy-metal but quite tough camera unit. Some day it will be injection molded instead...)
- brk 2y ago
  I will contact you, I may be able to help with a better solution. This is something I do a lot of.
  - dgacmu 2y ago
    Please do, I'd love to learn. We just completed a run of our latest version so we're a ways from thinking about a new design, but it would be helpful to know know what I should be thinking about for our roadmap. dave.andersen at Gmail is probably my easiest address.

KeplerBoy 2y ago

Isn't the Coral line already dead/discontinued? The site (coral.ai) seems to have been last updated in 2021 and it says Copyright 2020. Oh god, just searched for "google coral twitter" looking for an official twitter presence of the project and the second hit was a tweet of yours looking to sell your 100 excess boards.

michaelt 2y ago
Well, they haven't announced it's dead. In the electronics industry, even 30-year-old microcontrollers often have pin- and software-compatible replacements available to this day. So just because something has long been surpassed, doesn't mean it becomes unavailable. The electronics industry also has an orderly process for discontinuing parts, where customers are given advanced notice and a chance to place one last order if they want to stock up. This process hasn't been started for the Coral accelerators. With all that said - it's pretty clear that Google has lost interest in the product. When you're making hundreds of billions of dollars from ads, who's got the time for a product line that's bringing less than 0.1% of that? So personally I wouldn't base a new product on Coral today.
- Aherontas 2y ago
  It is really common for Google to delete projects out of the blue. So don't be surprised that they haven't much updates.
dgacmu 2y ago
I haven't seen anything official indicating it's discontinued, and they've released a few updated libraries, but there certainly seems to be very little momentum and I'm skeptical about its future. I think some friends have still bought the USB accelerator version of it to use with the frigate DVR, though. Not a good sign when offers to sell old ones feature prominently in the search results. :) It's a shame. They're actually really quite nice boards. I may have to sell them from the startup to my academic self and use them for some project or another if nobody wants them - but I don't really want to teach a machine vision course.

shrubble 2y ago

Curious if you have looked at the BeagleBone hardware with its PRU devices for low-power operation; they can stay awake while the system sleeps.