Maybe the "free" ad-supported cables could have limited charging or data transfer speeds, but those features could be unlocked by paying a subscription or watching more ads.
I'm more worried about companies forbidding third party cables or bricking cables you own. "Sorry, this cable was only licensed for 100 charging cycles. Please buy a new one, for your safety of course."
Any reasonable manufacturer will rotate firmware images and have the bootloader fall back to the most recent validated image. Though I imagine this could happen if this practice becomes common enough that you get it on some 5$ gas station charging cable kinda thing.
A reasonable manufacturer looks at its bottom line and doesn't waste his engineering hours and BOM costs (double the flash memory!) on silly features like that. Either that or there are many unreasonable manufacturers out there.
- How much do you think the NOR flash costs inside this cable?
- How big do you think the firmware actually is?
- 16MB Winbond NOR flash is like $0.70 with no price breaks (for me, I am not Apple making 1 million units) - there's no way they need 1MB for two slots, much less 16MB.
- These cables retail for $49.
Two firmware boot slots is standard practice because it is essentially free to provide in any higher-end consumer electronic device: especially one that is explicitly designed to be unplugged easily.
How many support claims are saved on this $49 cable because mid-update bricking does not occur?
Cost (reputational as well as CSR hours and the actual replacement units) of a bunch of warranty claims for bricked units is a factor too.
In practice pretty much every embedded device I've worked on that has supported in-field firmware updates has had either double buffering and/or a recovery mode to limit the possibility of bricking.
For the products where every last penny really needs to get squeezed out of the BOM (toys, low-end appliances, ...) the ability to do in-field firmware upgrades itself is IME often one of the first things to go.
A reasonable manufacturer who is releasing something that updates automatically with no warning to the user nor any indication an update is happening to alert the user that they should not disturb it to avoid bricking looks at the potential cost of a class action suit from people whose devices get accidentally bricked, the potential cost of regulators order the devices recalled as defective, and the potential damage to the reputation. This will almost certainly be more than what they'd save by not providing some way to automatically recover from an interrupted update.
BTW, they don't have to double the flash memory. They just have to provide enough extra memory for a fallback updater that the boot code can load if the main firmware is corrupt. All the fallback updater has to handle is telling the computer it needs firmware and then installing the firmware the computer provides.
That's what I was about to ask. It says that the cable should update itself transparently, but there can always be a chance of corruption. Maybe the cable keeps the old FW and only boots the new one if it is signed.
Presumably there is space for two copies of the firmware, and once the new one decompresses and checksums correctly you update the firmware-start pointer.
Really that shouldn't be called firmware (the actual firmware would be the fixed code that receives second-stage code from the host), but "software" doesn't fit that either. Maybe "controllerware" or something like that.
What I always understood firmware to be is: a ROM that gives a CPU something to do when power is applied, as RAM is blank on power on and things like storage devices can't just put stuff in RAM without being directed by the CPU (which doesn't have code to do that at power on unless provided by a ROM).
Depending on the scope of the device (from multipurpose PC down to single-purpose things like microwaves, gas pumps, hard drives, LCD controllers) the firmware may just allow an operating system to be loaded or actually be all the code the appliance needs for its CPU.
If the CPU is embedded in a peripheral, then:
- it has to have some small ROM that does nothing but wait for an image to come in from a bus (USB, etc.) and then execute. The sound chip in Nintendo's Super NES is an example, on power on/reset it has a 64 byte boot ROM that does nothing but wait for data to come in from the main 65816 CPU and then runs that code when received.
- the host has to have some way of externally programming the peripheral's RAM directly and resetting the peripheral's CPU but not the peripheral's RAM. I suppose JTAG could be used for this.
My opinion: CPU microcode isn't firmware - CPU microcode sets the configuration of internal connections/parameters in the CPU. It's kind of like a settings file. But: I think recent microcodes do actually include code (see Xucode) but that code is meant to be the behavior of advanced instructions and not designed to be something that tells the CPU what to do from the moment it's powered on.
There are plenty of things that have firmware, but run it out of RAM. FPGAs do this, and some microcontrollers. Dialog, now Renasas, has microcontrollers that run their firmware out of RAM.
Commonly there is a hardware peripheral that pulls the firmware from a couple of places (could be an onboard ROM, could be jtag, or other) and loads it in to RAM.
There’s no way to directly update the cable, but it should update automatically when plugged into your Mac. While you can check the firmware of your power adapter by attaching it to your Mac and clicking on the Apple logo in the top left corner of the menu bar, then About This Mac, System Report, and Power, it’s not clear how to check the specific firmware version of the cable.
So presumably there is some UART to the cable, and the cable to the power adapter. Is it all stuffed in the cable treated as a USB device or is there some proprietary control on the laptop side to communicate with the cable?
> The chip uses the 1-Wire protocol, which is a clever system for connecting low-speed devices through a single wire (plus ground). The 1-Wire system is convenient here since the Mac can communicate with the Magsafe through the single adapter sense pin.
The only interface the computer normally has to the cable is the single control pin on in the middle of the MagSafe connector, so they are likely having to do something more sophisticated than UART.
(Apple could have had you plug the other end that has the USB-C connector into the computer to do the firmware update, but that isn't particularly intuitive or user friendly).
* Translation between USB PD and whatever communication protocol runs on the center Magsafe pin (in Magsafe 1 and 2 it was Dallas 1-wire)
* Disabling power output when the cable is not connected to a computer, so that a metal object touching the spring pins can't create a dangerous short circuit
> What could possibly be the use for any sort of logic in such cable be, given that on both ends of it there’s already a computer as well?
Maybe because MacBooks can be charged via both USB-C and MagSafe connector it forms part of the safety mechanism against frying your motherboard and/or against arcing during connection/disconnection. Especially on the higher-end of the spectrum (e.g. 16-inch MacBooks with 140W MagSafe).
Sort of like the same way electric car chargers handshake before throwing amps down the cable.
The MagSafe connector only has three distinct contacts (there are five pins, but it's mirrored), so there has to be some protocol translation between USB PD and the single control signal used in MagSafe.
Just been scratching my head about this. Then I thought, is it just so they can detect authentic Apple cables and scold you for using an inauthentic one? Because iOS definitely does that. Some kind of challenge/response thing that requires a full Turing machine maybe.
Another thought was something to do with monitoring current or degradation but I cant see why they couldn’t do the same things from either the computer in the power adaptor or the computer in the actual computer.
> It’s not clear what the firmware fixes or patches
I'm on M2 MB Air, and it seems odd to me that it (seems to) runs off battery even when plugged in and fully charged. Mine has been plugged in at desk for over a week, every day when I get on it says it's "Power Source: Power Adapter" yet it battery charging goes "On Hold" and dwindles as if it's running off battery all day. For example, it's mid-day for me and I'm at 79% but it's never been unplugged.
My last was a MB Air 2013 so maybe this is new behavior that I'm just not used to, but it seems strange. If I had to unplug and leave, I'd expect to be leaving with 100% charge.
Edit: "Optimized Battery Charging" was turned on as commenter mentioned, thanks for the tech support HN!
80% is the 'ideal storage' condition for the battery. If it's always charging to 100%, the battery life is pretty dramatically shortened.
Apple enabled this new charging manager that tries to learn your patterns (if you always unplug in the AM and leave with it, it'll learn to charge to 100% before you leave, for example). You can also click the battery icon in the tray (if you have that turned on) and tell it to charge to 100% 'right now', which only takes a minute or two with a full size charger.
This is a positive thing for the life of your battery, but if you do want to disable it, there's a setting in System Settings - click the 'i' in the circle next to Battery Health, and turn off 'Optimize Battery Charging' there.
One of the many utilities I love that comes with my Set App subscription is AlDente Pro. As others have pointed out, it allows me to set 80% as the max for my battery and it also will change the color of the LED on the magsafe connector to green once it gets to 80% and charging stops.
I had optimized battery charging enabled but my Mac seemed to always charge to 100% - with Al Dente I can force it to do what I want.
And recently I found Al Dente pausing charging because the battery temp got too warm. So then I went down a rabbit hole and found out I could tweak the fans up slightly higher with iStat Menus (also part of my Set app sub).
There are other utilities that will do similar things - those just happen to be two I use, especially since I tend to use my MBP plugged in the majority of the time.
I was having problems charging with my magsafe cable and for the last month was using the usb-c port to charge.
Today i took if of the drawer and it is magically working again.
I am using the beta mac os 13.2 so it may have solved my problem.
I've had a new MacBook Air M2 for a few weeks now. I've been charging exclusively with a USB-C charger. Is there any advantage to charging via magsafe?
https://panic.com/blog/the-lightning-digital-av-adapter-surp...