201–210 of 309 posts
I wonder how much would it decrease the battery life to add a screen. Maybe just an e-ink display that refreshes to show the most recent image? I'd love to have a dead-simple point-and-shoot camera for my little kids to play with.
I hope OP doesn’t increase the cost of the product and decrease the battery life by adding edge case features like this.
That’s a pity. Though probably the use cases behind a window usually have access to power anyway and wouldn’t need this.
Earlier quoted context omitted.
Totally fair question! My reasons were: 1. To maximize Photon's battery life I tried to make the hardware do the absolute minimum to record imagery. To that end, Photon stores images on an unformatted SD card (ie one huge linear array of bytes) which is easy and fast to index into. 2. A 16-bit MSP430 handles writing the image data, and the MSP430's codespace is 99% exhausted without dealing with the complexities of a…
how do you manage the balancing of card use, or is there still a card firmware layer in the loop that does that? eg lower memory being used far more often over the life so wearing out well before upper memory? how do you handle memory dropouts for a given address/cell/whatever you call a memory location, or as above?
The SD card is accessed as a ring buffer, so all addresses are written evenly. (It was my understanding that SD cards implement wear leveling themselves though, so the wear leveling should be free even if the SD card was written to randomly -- if my understanding is correct.)
> how do you handle memory dropouts for a given address/cell/whatever you call a memory location, or as above?
SD card write failures cause the firmware to crash and reset itself, so it'll try again when another photo is triggered. (It also logs the reset so it can be debugged.)
FWIW I'm using Samsung 128 GB "PRO Endurance" SD cards, with endurance == 820 TBW, which works out to 820e12 / 5.97e6 (size of one photo) == 137e6. So you can capture 137 million photos before the SD card is expected to fail.
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> That is likely even lower than the effective self discharge rate of a lithium coin cell battery. That's what I've found too. Based on my measurements and calculations, Photon uses 5µA (MSP430 + motion sensor) while sleeping, while the battery's self-discharge is more like 80µA. That's probably a good argument for using a more powerful chip though, if the battery self-discharge is that high, hah.
Or a different battery chemistry with a lower self discharge rate. No need to be rechargable in most of the use cases, I'd imagine.
The guys with the purple LiSoCl2 batteries make ones with up to 40 years of usable life
Earlier quoted context omitted.
> That is likely even lower than the effective self discharge rate of a lithium coin cell battery. That's what I've found too. Based on my measurements and calculations, Photon uses 5µA (MSP430 + motion sensor) while sleeping, while the battery's self-discharge is more like 80µA. That's probably a good argument for using a more powerful chip though, if the battery self-discharge is that high, hah.
Or a different battery chemistry with a lower self discharge rate. No need to be rechargable in most of the use cases, I'd imagine.
Earlier quoted context omitted.
Not the OP, but my understanding (admittedly a few years outdated) is that an MSP430 will, in idle, with sleep states properly set up and low power modes in use, drain a coin cell battery (e.g. CR2032) over a period of years - with the current drawn around 1.5 uA in standby and 0.1uA in RAM retention idle. That is likely even lower than the effective self discharge rate of a lithium coin cell battery. I don't believe…
> That is likely even lower than the effective self discharge rate of a lithium coin cell battery. That's what I've found too. Based on my measurements and calculations, Photon uses 5µA (MSP430 + motion sensor) while sleeping, while the battery's self-discharge is more like 80µA. That's probably a good argument for using a more powerful chip though, if the battery self-discharge is that high, hah.
Earlier quoted context omitted.
Or a different battery chemistry with a lower self discharge rate. No need to be rechargable in most of the use cases, I'd imagine.
This sounds like a job for a lithium thionyl chloride battery. The guys with the purple LiSoCl2 batteries make ones with up to 40 years of usable life
Okay, you also made a drag and drop terminal app for rebasing?? Super cool products all round. True hacker news. https://toaster.llc/debase/index.html
This is really cool. As a software guy, how can I learn more about making PCBs (other than the linked blog)?
“Photon's motion sensor can't detect motion behind glass.” That’s a pity. Though probably the use cases behind a window usually have access to power anyway and wouldn’t need this.
> When placed in nature, Photon's motion sensor tends to trigger often due to grass or leaves blowing in the wind, which can cause Photon's battery to deplete quickly if configured to capture a photo when motion occurs. A future software update may provide a motion-sensitivity setting to help address this scenario.
So, not behind a glass and not outside a glass. Maybe I could place it close to my front door and check who rings to me and which cats pass by? I hope that software update will happen soon. On the other side, the demo images on the Mac app page seem to be all outdoor pictures, so I wonder if excessive motion sensitivity is really an issue.