So the way this works seems to be this: It's an SRAM and an EEPROM in one little package along with a controller that talks with each, with a little capacitor (this clock uses 4.7uf) placed nearby.
The SRAM part does all of the normal SRAM stuff: It doesn't wear out from reading/writing, and as long as it has power it retains the data it holds.
The EEPROM does all the normal EEPROM stuff: It stores data forever (on the timescale of an individual human, anyway), but has somewhat-limited write cycles.
The controller: When it detects a low voltage, it goes "oh shit!" and immediately dumps the contents of the SRAM into EEPROM. This saves on EEPROM write cycles: If there are no power events, the EEPROM is never written at all.
Meanwhile, the capacitor: It provides the power for the chip to perform this EEPROM write when an "oh shit!" event occurs.
When power comes back, the EEPROM's data is copied back to SRAM.
---
Downsides? This 47L04 only holds 4 kilobits. Upsides? For hobbyist projects and limited production runs, spending $1 to solve a problem is ~nothing. :)
Has anyone found the chip on AliExpress? I only get unrelated listings with that part number, but this is a pretty interesting chip I'd like to get a few of.
An alternative would be a supercapacitor and a voltage divider connected to the ADC pin of the microcontroller. When the 5V rail dies, the supercapacitor can hold 3.3V for a few seconds while you write everything to the EEPROM.
It's as if people have never had shipping itemized before.
The only reason aliexpress shopping is cheap is because the rest of the world foots the bill. Unless somebody has finally removed China's "Developing Country" status thats gotten them essentially free international parcel service for the best part of 100 years.
Yeah OK, but if I only want 5 pieces and I have to choose between $5 or $30, I'm not going to think about the geopolitical situation, I'm just going to get the cheaper one.
I buy small parts with "Choice" shipping on AliExpress sometimes, because it's cheap and [usually] quick and they take care of all of that pesky tariff and customs business in ways that never have an opportunity to surprise me.
For years now, the shipping process has worked like this for me: They gather it up on their end and send the stuff on a cargo plane to a sort that is at or near JFK airport in New York.
If the order includes things from several different sellers, then at some point they generally get combined into one bag.
From there, they just mail it -- using regular, domestic USPS service. It shows up in my mailbox on my porch in Ohio a few days later.
Although it certainly was a thing I've experienced in the past, at no point does the process I've described exploit the "Developing County" loophole. They just send things to the other side of the world (at their expense), and then pay the post office the same way as anyone else does to bring it to my door.
EDIT: Oh lord, bad typo in my previous comment- it should have been aliexpress SHIPPING not Shopping.
It's not the same, what you described is Direct Entry (somewhere around page 25, linked below). Apparently the Terminal Dues system has been massively changed in the 5 years since I last looked- but it still appears unfavorable to USPS and US sellers, while favoring high volume foreign shippers.
As for how aliexpress delivers stuff, since the tarrifs: 1) no-name last mile. 2) USPS last mile, and USPS the entire way.
I don't know if any are associated with "Choice", Paid store shipping, and/or free store shipping.
Since I normally buy from aliexpress to avoid the insane 200-800% markups amazon/ebay/walmart/etc dropshippers demand the $5-$10 in shipping doesnt factor in.
"Hey, someone on the Internet used decent diction! Obviously, this means I must accuse them of being a bot!"
(Hey Dang. Can we get a ban button? There's a few people here that are impossible to conduct rational discourse with. My sanity would improve if they were simply gone from my view.)
Yes! The reflexive “must be LLM generated” is becoming ridiculous. Anything that includes proper punctuation and, god forbid, em dashes which I’ve used all my life must be suspect. The “it’s not x, it’s y” construction predates LLMs. I don’t recall ever sending a text without making sure it contained no errors, and yes, many have included infrequently used vocabulary.
I've been trying to write properly, clearly, and with the most expressive words I can come up with for many decades. I try to punctuate well, and to use functional formatting that I hope helps to effectively convey whatever it is that I'm on about. I try to improve as time goes on.
And I do this because if I'm going to bother with writing something for others to read, then I want my intended meaning to be easily-understood.
But increasingly, the instances where I manage to not screw any of that up too terribly result in a snarky and insulting retort in return.
And that kind of response is just not useful to anyone. I mean: What would people presume to have me do, instead? Become less-literate? Die in a fire? (Worse?)
It’s frustrating to the point that I have considered inserting grammatical errors, but that would go against my principles, which I have attempted to inculcate in my children. Yes, a significant amount of what’s posted is copied and pasted AI slop. But what in the world preceded this? Barely legible slop? I would much rather have someone craft their thoughts, run them through their preferred model, and write something coherent that is not marred by punctuation or basic elementary grammar errors. And you know what, the hell with the AI slop police. Yes, if we choose to use em dashes, we will.
An extra UI element or two should be enough. Maybe with sticky options for collapse-by-default or hide-by-default at the top of each HN comment section.
And the list of usernames can be stored and edited in the purveyor's HN bio (in plain text, like a monster), so that it works automatically across devices.
Upvoted because this stinks to high hell of an LLM response. Half the GPs comments seem to be in a similar vein. It’s such a shame but you can’t fight the trolls so don’t take it to heart.
So the way this works seems to be this: It's an SRAM and an EEPROM in one little package along with a controller that talks with each, with a little capacitor (this clock uses 4.7uf) placed nearby.
The SRAM part does all of the normal SRAM stuff: It doesn't wear out from reading/writing, and as long as it has power it retains the data it holds.
The EEPROM does all the normal EEPROM stuff: It stores data forever (on the timescale of an individual human, anyway), but has somewhat-limited write cycles.
The controller: When it detects a low voltage, it goes "oh shit!" and immediately dumps the contents of the SRAM into EEPROM. This saves on EEPROM write cycles: If there are no power events, the EEPROM is never written at all.
Meanwhile, the capacitor: It provides the power for the chip to perform this EEPROM write when an "oh shit!" event occurs.
When power comes back, the EEPROM's data is copied back to SRAM.
---
Downsides? This 47L04 only holds 4 kilobits. Upsides? For hobbyist projects and limited production runs, spending $1 to solve a problem is ~nothing. :)