10-08-2018, 22:11
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#1 (permalink)
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| Crazy Poster
Join Date: Oct 2015
Posts: 57
Member: 2466640
Status: Offline Thanks Meter: 18 | Apple Watch knowledge dump
The company I work(ed) for closed their doors rather suddenly; my last day was 10/3. I dunno what's in my future work-wise, but the iBus and MFC devices were company property and so I don't have them. I may never work on another Apple Watch.
But the good news is that since the company is gone, there's nobody to complain if I share stuff I learned on the company's dime, right? Earlier I posted a link to the iFixit howto I made on Frankenstein-ing a Series 2 Display onto a Series 3 Watch. Here is a text file I kept on my desktop containing all the little stuff I learned about these Watches. It wasn't really intended to be public-facing, just notes to remind of things I already knew. But I'll post it here in case you-all might find any useful tidbits... Quote:
When the Apple Watch ("AW") was introduced there were no "Series", just the AW. Later on a new model was introduced with a faster processor and better graphics; this was called the "Series 1" and the original AW was retconned as the "Series 0". When you look at the back of the AW the S0 has the Serial Number ("SN") etched around the edge of the Heart Rate Sensor ("HR"). The S1, 2, and 3 have "Series x" etched around the top of the HR and the SN is etched inside one of the band cavities.
For testing, you can put a 38mm battery in a 42mm AW, it just rattles around a little. You can also use a 42mm Display for testing a 38mm AW; there will be bands of noise along the right side and bottom of the 42mm Display. You can put a 38mm Display on a 42mm AW however the right side and bottom will not be accessible. This includes the bit you need to tap to Reset the AW.
Some AW require a certain minimum iOS to pair with a phone. So you'll need iOS 9, 10, 11, and 12 test iPhones (at least!). The reason for this is that some users may have decided not to update the iOS on their phone. If we update the Watch to pair with a higher version of iOS then when the user gets their AW back and they try to pair it, they will be forced to update their phone's iOS version. So when working on a live job (i.e. not Asset Recovery) you should pair the AW with the lowest version of iOS that will accept it.
When the AW needs a higher iOS, during the pairing process the phone will display a message prompting you to update the phone. When the AW needs a lower iOS, the phone will display a message prompting you to update the AW. In either case, DO NOT UPDATE! Abort the pairing process and switch to a different test phone with the appropriate iOS version.
AW with WatchOS2.x or earlier will only work with certain charging pods. If you try a new charger with an old AW the AW will display a message saying "update the AW to use this accessory". If it's a live job, DO NOT UPDATE! (See above.) Find one of the old, WatchOS2-compatible chargers and use that. Usually the incompatible charger will work to charge the AW up to about 10%, then it will complain about compatibility and not charge further. For Asset Recovery jobs, you may need to use the old charger long enough to get the AW updated so it will accept any chargers. The older, WOS2-compatible chargers I've found have all been the 2-meter cable variety. All the 1-meter chargers I've tested have been too new for WOS2. But not all of the 2-meter chargers are compatible; you have to experiment.
On S0 and S1 AW, there is firmware in the digitizer that has to be compatible with firmware in the OLED. So if you buy a replacement digi and attach it to a scavenged OLED, you might not get any response from the digi. The fix for this is to reflash the OS on the AW; this downloads fresh (and compatible) code to the digi and/or OLED (not sure which) and then it works.
We've bought "iBus" tools and an "MFC Dongle" from http://www.mfcbox.com
The iBus (there's an S1 for S0 and S1 AW and an S2 for S2 and S3 AW) connects to the maintenance port inside the band cavity to a PC/Mac via a Lightning cable. iTunes can be used to reflash the firmware on an AW. You have to get an IPSW file that is iTunes-compatible and compatible with the specific AW. The files are different for S0, S1, S2, S3 and different for 38mm and 42mm. Also they're different for S3 wifi and S3 4G. An Over-The-Air ("OTA") update file will not work with iTunes. Once you've got the file, open iTunes, connect the AW to the PC. Hold Shift and click "Restore" in iTunes. Now you'll get a file selection dialog where you can point to the appropriate IPSW. The catch with this is that Apple doesn't publish these files so they have to be exfiltrated somehow from an Apple service center.
The folks at MFCbox sometimes obtain IPSW files at some expense to themselves. They wrap these files in an extra encryption layer so that they can only be used with the "MFC Dongle" software. These IPSW can be downloaded from mfcbox.com if you log in.
Another catch is that the IPSW files contain components that are cryptographically signed by Apple. At some point Apple pulls the certificate associated with a particular revision and that IPSW will no longer work. Then you have to wait for mfcbox to produce files with signed components. This is true of both iTunes-compatible IPSW and MFC Dongle-compatible IPSW files.
If you change the extension from "IPSW" to "ZIP" you can open an IPSW file with any program that can read ZIP archives. I don't know if you can do anything useful with it once you've opened it, but that would probably be the first step towards making your own iTunes-compaible IPSW.
S2 and S3 AW also have Display compatibility issues; the symptom is that the AW will not pair with a phone. The best workaround is to pair using the original Display, even though it's broken. This is pretty easy with WatchOS4.x and above, because the AW will go into the pairing image without having to use the touchscreen on the AW. After the AW is paired you can switch to a test Display and do whatever testing is needed. If a replacement Display is installed and the AW won't pair reflash the AW using the iBus device. This updates the code on the Display to something compatible with what's on the mainboard. Note that this may mess with the iOS version compatibility nonsense.
S3 Watches shipped with WatchOS 4.[something] but some S2 AW are out there with 3.x; these require a workable touchscreen to get into pairing mode. I have three 42mm and two 38mm S2 Displays that (apparently) have different firmware revisions. I try various Displays until I find one that allows the AW to pair. Do not reflash the OS on an AW with a test Display attached as this will replace the firmware on the test Display and we need the variety.
The "MFC Dongle" is a hardware device that's primarily used to crack passcodes on older (8.x and previous) iOS and some Android devices. Doing this requires "credits" which have to be purchased from mfcbox.com and are consumed when a passcode is cracked. Fortunately flashing an AW does not use credits but the MFC Dongle software must see the hardware attached before it will unlock the reflash functionality.
S2 and S3 Displays look the same; they have the same connector layout and the flex cables line up and fit. But there is a difference -- the Light Sensor/NFC module is different. If you put an S2 Display on an S3 AW the LS/NFC will get very hot, the battery runs down in just a few minutes and it won't charge. However the module doesn't appear to be damaged. If you take the LS/NFC module from a broken S3 Display and transplant it onto a working S2 Display this works as a replacement for the broken S3 Display. The transplanted module MUST come from the original Display; there is a cryptographic link between the NFC and the AW mainboard and if the module doesn't match the mainboard everything works except Apple Pay.
Wrap 3 turns or so of a Kimtech wipe around the stick of a cotton swab. Dip this in isopropyl and it makes a good tool for cleaning inside the band cavities. The silicone bands clean up pretty well with the blue glass cleaner. Sometimes isopropyl may be needed; depends on what's on them. If they're badly soiled the finish might be damaged. A tissue soaked in acetone is good for top-dressing the band. Acetone attacks the silicone a little bit so it's not a good choice as a cleaner but it will put a nice even patina on a badly worn band after cleaning.
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