3 ms·

It's a neat proof-of-concept, but the video gets a little optimistic and hand-wavey about how practical this could actually ever be. "Right now we have interru

by hbn 4y ago

It's a neat proof-of-concept, but the video gets a little optimistic and hand-wavey about how practical this could actually ever be. "Right now we have interruptions, but[...] that interruption amount is going to continually decrease as we make these systems better and more energy-efficient." Is that really the case? The limiting factor here is not just the efficiency of harvesting energy. The energy being harvested from the sun and from the button presses has a hard cap at some point, and while I don't know enough about the topic to do the math, I'd have to assume it's not particularly high. Even if you were able to harvest 100% of the sunlight hitting a smartphone (quick Google search says solar panels harvest ~15%), and 100% of the energy from the taps of a user's finger, would that be anywhere close to enough power to run the thing? This seems like more of a conceptual limit than a technological one.

colechristensen 4y ago
With magic solar panels and full sun an iphone shaped solar cell could charge my iphone fully in under an hour and a half. Good commercial solar cells can get a little more than 20% efficiency so really with good sun and a bit of restricted usage an iphone with a solar cell for a back that got a lot of sunshine could power itself enough to be practically useful. With the ability to scale down the power usage with processors that do a whole lot less it’s certainly practical to get much more out of usable processors. You can do a lot with, say, 10 watt hours per day and that much is certainly achievable on a hand held device.
jetbooster 4y ago
Without concentrating the sunlight, the max efficiency of a solar panel is about 68% conversion. With 1kW/m², and a solar panel the size of a 0.01m² phone (6.1 inch, 16:9) that's 6.8W to play with, at the theoretical maximum. A quick check states a Raspberry Pi 4B at 100% CPU draws 6.4W, so in perfect conditions with a perfect panel, it's just about approaching feasible to run a chip on a phone sized panel. However a Gameboy is much simpler than a Pi. It seems the Gameboy draws about 70-80mA@1.5V, or 0.1W, which is very impressive. I would say that would 100% be physically feasible to power with a gameboy sized solar panel in our lifetime.
- whoisthemachine 4y ago
  That's interesting, with so much juice available, it seems like it would be worthwhile to pursue this project with the original hardware rather than adding in the snapshotting and emulation, which definitely makes a more robust system, but adds lots of extra power consumption.
LeifCarrotson 4y ago
The efficient processor they've chosen requires on the order of 20 microamps per megahertz at 1.8V to run code out of Flash, or 1.7 milliwatts of power. It draws only about 0.004 milliwatts in deep sleep, and takes less than a microsecond to enter and exit deep sleep. Their energy-harvesting switches produce 0.33 milliwatt-seconds when pressed or released. So you want to be efficient and enter deep sleep whenever possible. If you can have a duty cycle that looks like "Take sensor reading and run computation when button is pressed or when timer elapses, transmit over BLE, update e-ink display, or whatever our device does, then go back to sleep after 2 ms" that's easy - at even absurdly fast update rates of ~20 Hz, you're only using a 4% duty cycle and drawing an average of just 0.07 mW, requiring one button press every 10 seconds or so. If you've got 3 button clicks per second, you can stay active all the time. But neither a 3 Hz button-press rate, nor a non-sleep-using firmware are reasonable. Of course, when you're bringing in a full ~10 mW of power continuously from the solar panels, the buttons are kind of a nice-to-have, you'd have to mash them at crazy rates to even equal the panels. They're not even close to the potential efficiency of the processor - they're running an emulator for goodness' sake, which was almost certainly not designed with power saving in mind. If they started from the ground up reverse-engineering the Gameboy functions with the goal of maximizing power efficiency, yes, it's perfectly reasonable to assume that they could run continuously.
- initramfs 4y ago
  The processor used was an Ambiq Apollo3. The 22nm Apollo4 is out and uses around 5uA/Mhz. Ambiq is also working on a 12nm Apollo5 with an interest in developing a linux SoC: https://ambiq.com/wp-content/uploads/2023/02/A-Vision-for-Ambient-Computing-White-Paper.pdf https://ambiq.com/wp-content/uploads/2023/02/A-Vision-for-Am... p.10 "Explorations of Linux/Android-grade processors in an "Apollo-like" power footprint"
- initramfs 4y ago
  Yes continuously. This capacitor has 11mAh capacity, which could run a flip phone with an Ambiq processor and a monochrome screen for 2-3 hours continuously. The 250F size has the equivalent of 90MAh. They used a capacitor that has much lower capacity, and Lithium-Ion Capacitors were not very common in 2020: https://www.farnell.com/datasheets/3816249.pdf https://www.farnell.com/datasheets/3816249.pdf https://www.farnell.com/datasheets/3816250.pdf https://www.farnell.com/datasheets/3816250.pdf

by hbn 4y ago

colechristensen 4y ago

With magic solar panels and full sun an iphone shaped solar cell could charge my iphone fully in under an hour and a half. Good commercial solar cells can get a little more than 20% efficiency so really with good sun and a bit of restricted usage an iphone with a solar cell for a back that got a lot of sunshine could power itself enough to be practically useful. With the ability to scale down the power usage with processors that do a whole lot less it’s certainly practical to get much more out of usable processors. You can do a lot with, say, 10 watt hours per day and that much is certainly achievable on a hand held device.

jetbooster 4y ago

Without concentrating the sunlight, the max efficiency of a solar panel is about 68% conversion. With 1kW/m², and a solar panel the size of a 0.01m² phone (6.1 inch, 16:9) that's 6.8W to play with, at the theoretical maximum. A quick check states a Raspberry Pi 4B at 100% CPU draws 6.4W, so in perfect conditions with a perfect panel, it's just about approaching feasible to run a chip on a phone sized panel. However a Gameboy is much simpler than a Pi. It seems the Gameboy draws about 70-80mA@1.5V, or 0.1W, which is very impressive. I would say that would 100% be physically feasible to power with a gameboy sized solar panel in our lifetime.

whoisthemachine 4y ago
That's interesting, with so much juice available, it seems like it would be worthwhile to pursue this project with the original hardware rather than adding in the snapshotting and emulation, which definitely makes a more robust system, but adds lots of extra power consumption.

LeifCarrotson 4y ago

The efficient processor they've chosen requires on the order of 20 microamps per megahertz at 1.8V to run code out of Flash, or 1.7 milliwatts of power. It draws only about 0.004 milliwatts in deep sleep, and takes less than a microsecond to enter and exit deep sleep. Their energy-harvesting switches produce 0.33 milliwatt-seconds when pressed or released. So you want to be efficient and enter deep sleep whenever possible. If you can have a duty cycle that looks like "Take sensor reading and run computation when button is pressed or when timer elapses, transmit over BLE, update e-ink display, or whatever our device does, then go back to sleep after 2 ms" that's easy - at even absurdly fast update rates of ~20 Hz, you're only using a 4% duty cycle and drawing an average of just 0.07 mW, requiring one button press every 10 seconds or so. If you've got 3 button clicks per second, you can stay active all the time. But neither a 3 Hz button-press rate, nor a non-sleep-using firmware are reasonable. Of course, when you're bringing in a full ~10 mW of power continuously from the solar panels, the buttons are kind of a nice-to-have, you'd have to mash them at crazy rates to even equal the panels. They're not even close to the potential efficiency of the processor - they're running an emulator for goodness' sake, which was almost certainly not designed with power saving in mind. If they started from the ground up reverse-engineering the Gameboy functions with the goal of maximizing power efficiency, yes, it's perfectly reasonable to assume that they could run continuously.

initramfs 4y ago
The processor used was an Ambiq Apollo3. The 22nm Apollo4 is out and uses around 5uA/Mhz. Ambiq is also working on a 12nm Apollo5 with an interest in developing a linux SoC: https://ambiq.com/wp-content/uploads/2023/02/A-Vision-for-Ambient-Computing-White-Paper.pdf https://ambiq.com/wp-content/uploads/2023/02/A-Vision-for-Am... p.10 "Explorations of Linux/Android-grade processors in an "Apollo-like" power footprint"
initramfs 4y ago
Yes continuously. This capacitor has 11mAh capacity, which could run a flip phone with an Ambiq processor and a monochrome screen for 2-3 hours continuously. The 250F size has the equivalent of 90MAh. They used a capacitor that has much lower capacity, and Lithium-Ion Capacitors were not very common in 2020: https://www.farnell.com/datasheets/3816249.pdf https://www.farnell.com/datasheets/3816249.pdf https://www.farnell.com/datasheets/3816250.pdf https://www.farnell.com/datasheets/3816250.pdf