i almost didn't open this because it said 'e-paper' and i've sort of dismissed e-paper for this kind of thing
this is much more interesting than an e-paper device; it's a memory-in-pixel lcd device, which means 100 times better refresh rate and 1000 times better power consumption than e-paper. the lcd in question (ls027b7dh01, i assume, though that information is missing from the web pages) is supposed to run on 175μW at 20fps, so you can get a full usable computer system in submilliwatt territory, so the 2.2 kilojoules in a cr2032 can power it for weeks
however, i think that, as a low-power device, this is probably fatally flawed. the rp2040 dooms it; the rp2040 lacks a reasonable deep-sleep mode; its lowest-power mode is nearly a milliwatt, so it will drain the battery flat when it's not being used
also it's unclear, in this design, how much the rp2040 can do without powering up the pi zero, which is a humongous power hog, using over 1000 milliwatts. so instead of weeks of active use from a cr2032 (and months of standby if you use a low-power micro instead of an rp2040) you get hours
what's the point of using a super expensive memory-in-pixel lcd to get the display power consumption down from e-paper's 10-100 milliwatts into submilliwatt territory if you're just going to burn a thousand milliwatts in a raspberry pi? just use a conventional lcd then, maybe one with nice 24-bit color. old nokia lcds will run on a milliwatt
maybe an esp32 would be a better middle ground if you aren't willing to go all the way to an ambiq apollo3 or something, which can (hypothetically) give you submilliwatt power consumption with workstation-class performance, as long as you don't need virtual memory; you probably want an esp32 or equivalent in there anyway for wi-fi
usb-c is a great way to be able to hook up a full-size external keyboard, but speaking usb-c to a keyboard is also probably beyond the capabilities of the rp2040, and so would also need to power up the giant power hog pi zero
this is much more interesting than an e-paper device; it's a memory-in-pixel lcd device, which means 100 times better refresh rate and 1000 times better power consumption than e-paper. the lcd in question (ls027b7dh01, i assume, though that information is missing from the web pages) is supposed to run on 175μW at 20fps, so you can get a full usable computer system in submilliwatt territory, so the 2.2 kilojoules in a cr2032 can power it for weeks
however, i think that, as a low-power device, this is probably fatally flawed. the rp2040 dooms it; the rp2040 lacks a reasonable deep-sleep mode; its lowest-power mode is nearly a milliwatt, so it will drain the battery flat when it's not being used
also it's unclear, in this design, how much the rp2040 can do without powering up the pi zero, which is a humongous power hog, using over 1000 milliwatts. so instead of weeks of active use from a cr2032 (and months of standby if you use a low-power micro instead of an rp2040) you get hours
what's the point of using a super expensive memory-in-pixel lcd to get the display power consumption down from e-paper's 10-100 milliwatts into submilliwatt territory if you're just going to burn a thousand milliwatts in a raspberry pi? just use a conventional lcd then, maybe one with nice 24-bit color. old nokia lcds will run on a milliwatt
maybe an esp32 would be a better middle ground if you aren't willing to go all the way to an ambiq apollo3 or something, which can (hypothetically) give you submilliwatt power consumption with workstation-class performance, as long as you don't need virtual memory; you probably want an esp32 or equivalent in there anyway for wi-fi
usb-c is a great way to be able to hook up a full-size external keyboard, but speaking usb-c to a keyboard is also probably beyond the capabilities of the rp2040, and so would also need to power up the giant power hog pi zero