eMMC Adventures, Episode 2: Resurrecting a dead Intel Atom-based tablet by replacing failed eMMC storage

As seen on Hackaday!

Recently, I purchased a cheap Intel Atom-based Windows 8 tablet (the DigiLand DL801W) that was being sold at a very low price ($15 USD, although the shipping to Canada negated much of the savings) because it would not boot into Windows – rather, it would only boot into the UEFI shell and cannot be interacted with without an external USB keyboard/mouse.

The patient, er, tablet

The tablet in question is a DigiLand DL801W (identified as a Lightcomm DL801W in the UEFI/BIOS data). It uses an Intel Atom Z3735F – a 1.33GHz quad-core tablet SoC (system-on-chip), 16GB of eMMC storage and a paltry 1GB of DDR3L-1333 SDRAM. It sports a 4500 mAh single-cell Li-ion battery, an 8″ 800×1200 display, 802.11b/g/n Wi-Fi using an SDIO chipset, two cameras, one microphone, mono speaker, stereo headphone jack and a single micro-USB port with USB On-The-Go support (this allows the port to act as a USB host port, allowing connections with standard USB devices like keyboards, mice, and USB drives).

Step 1: Triage & troubleshooting

The first step was to power on the tablet to get an initial glimpse into the issues preventing the tablet from booting. I was able to confirm that the eMMC was detected, but did not appear to have any valid MBR or file system; therefore, the UEFI firmware defaulted to entering the UEFI shell (which was of little use on its own as there is no on-screen keyboard available for it).

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DigiLand DL801W with UEFI shell

However, one can immediately notice there is an issue with the shell: how do you enter commands without an on-screen keyboard? The solution was to use a USB OTG (On-The-Go) dongle to convert the micro-USB type B port into a USB type A host port.

Using the shell commands, I tried reading the contents of the boot sector, which should end with an MBR signature of 0x55AA. Instead, the eMMC returned some nonsensical data: the first half of the sector had a repeating byte pattern of 0x10000700,  and the second half was all zeroes (0x00) except the last 16 bytes which were all ones (0xFF). The kicker was that this data was returned for every sector I tried to read. No wonder the eMMC was unbootable – the eMMC had suffered logical damage and the firmware was not functioning correctly.

After creating a 32-bit Windows 10 setup USB drive (these cheap low-RAM PCs often use a 32-bit UEFI despite having a 64-bit capable CPU), I opened Hard Disk Sentinel to take a deeper look at the condition of the onboard eMMC.

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Malfunctioning Foresee 16GB eMMC visible in Hard Disk Sentinel

The eMMC identified itself with a vendor ID of 0x65, and an MMC name of “M”. It reported a capacity of 7.2 GB instead of the normal 16 GB, another sign that the eMMC was corrupted at the firmware level.

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Foresee 16GB eMMC returning corrupted data

Using HDS, I performed a read scan of the entire eMMC despite its failed condition. The read speeds were mostly consistent, staying between 40 to 43 MB/s. A random read test revealed a consistent latency of 0.22 ms.

In order to assess whether the eMMC was writable in its current state, I ran a zero-fill and subsequent read scan. The eMMC appeared to accept writes but did not actually commit them, as HDS threw verification errors for all sectors.

After the tests in HDS, I decided to attempt an installation onto the eMMC to assess its writability. Windows Setup failed to create the disk partition structures, throwing an error message reading “We couldn’t create a new partition or locate an existing one”.

Step 2: Teardown & eMMC replacement

Since the onboard Foresee NCEMBS99-16G eMMC module was conclusively determined to be faulty, there was no point keeping it on the tablet’s motherboard. This also provided an opportunity to upgrade the eMMC to a a larger and faster one. Since this required the tablet to be disassembled, I decided to do a teardown of the tablet before attempting to replace the failed eMMC module (the teardown will be in a separate blog post when the time comes).

After removing the insulating plastic tape on the bottom of the PCB, I masked off the eMMC with some kapton tape to protect the other components and connectors from the heat of my hot-air rework station. With some hot air and patience, the failed Foresee eMMC was gone. This also revealed that the eMMC footprint supported both the 11.5×13 mm and 12×16 mm sizes, but the 12×16 mm footprint did not have the extra 16 solder balls for reinforcement (most eMMC balls are unused so their omission had no negative functional effect).

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Foresee eMMC removed from DL801W’s motherboard

Instead of a barely-usable 16 GB of eMMC storage, I opted to use the Samsung KLMBG4GEND-B031 – a 32 GB eMMC 5.0 module. This chip boasts more than 2000 IOPS for 4K random I/O, which should be a boon for OS and application responsiveness.

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Replacement Samsung KLMBG4GEND-B031 eMMC installed

A little flux and hot air was all I needed to give the 32 GB eMMC a new home. Time to reassemble the tablet and try installing Windows 10 again.

Step 3: OS reinstallation

After spending a few minutes cleaning the board and reinstalling it in the tablet, it was time to power the tablet back on, confirm the presence of the new eMMC and reattempt installing Windows.

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Installing Windows 10 from USB drive via USB-OTG adapter

The eMMC replacement proved to be successful; within minutes, I was off to the races with a clean installation of Windows 10.

Conclusion

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DL801W restored, running Texas Instruments’ bqSTUDIO software

This was a pretty fun project. With some electronics and computer troubleshooting skills, I had a tablet capable of running desktop Windows programs. Its low power consumption and USB host capabilities made for a great platform to run my Texas Instruments battery hardware and software without being tethered to my desktop.

However, I was not finished with this tablet. The 1 GB of onboard RAM made Windows painfully slow to use, as the CPU was constantly bogged down performing memory compression/decompression. The 32GB of eMMC storage I initially installed began feeling cramped, so I moved to a roomier 64GB (then 128GB) eMMC.

I won’t go into the details of how I upgraded the RAM in this post, as it’s a long story; simply put, soldering the RAM ICs was the easy part.

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WordAds Adventures, Episode 3

Another month has passed and that means another round of ad revenue trickling in.

Results for January 2018

This is rather interesting – despite getting more views than December 2017, the pay rate was lower than before!

Curious to see what the dollar-per-impression rate was for each month, I tabulated the results and graphed them:

Period Earnings Visitors Views Ads Served $/Impression
Nov 2017  $     5.03 3833 8538 4648  $ 0.00108219
Dec 2017  $   15.18 4344 9732 17369  $ 0.00087397
Jan 2018  $   11.96 4359 9458 17887  $ 0.00066864

WordAds Rate Nov 2017 to Jan 2018

That is a pretty linear drop in dollar-per-impression rate. Perhaps this is due to ad market fluctuations, or maybe WordPress is “incentivizing” increased viewership to maintain ad revenue. Who knows? Either way, it will be interesting to track this trend as time goes on.

Mini-Ramble: WordAds – I think it’s working!

Over a month has passed since my first post about seeing where the WordAds train will take me and my blog, and the first (meaningful) payout numbers have rolled out.

Current Earnings

ss (2018-01-05 at 12.42.57)

WordAds earnings for 1/3 of November 2017, and all of December 2017.

Not too bad – in 1 1/3 months, I’ve earned $20.20 USD in ad revenue. In December alone I earned $15.18 from 17,369 attempted ad impressions; with 9,732 views in December this equates to an impression-to-view ratio of 1.785.

Assuming that I receive the same number of views per month, $15/month * 12 months = $180 USD/year. With this amount of revenue, my blog can finally run itself!

Blog Budget Breakdown (yay, alliteration!)

Item  Value 
Yearly Ad Revenue ($15 USD * 12 months)  $ 180.00
Domain Name Registration (1 year for 3 domains, assuming CAD-to-USD conversion rate of 0.8x)  $  (76.80)
G Suite (1 year, assuming CAD-to-USD conversion rate of 0.8x)  $  (48.00)
Final Balance (USD)  $   55.20

If I assume that my current view count doesn’t change, this would leave me with a little over $50 USD in pocket change by the end of the year. Perhaps this money could be put to use to buy some more things to make blog posts with – maybe some iPhone batteries or an eMMC module or two…

Once again, thanks to all of my readers – I couldn’t have done any of this without you! 😀

Packing Boxes & Stomachs: Edible foam packing peanuts?!

Earlier today I picked up my replacement fire extinguisher from Kidde (check out the recall here) and noticed the packing peanuts weren’t the pearlescent S-shaped Styrofoam peanuts I was used to seeing – rather, they looked like fluffier versions of Cheetos (cheese puffs). This piqued my curiosity… can you eat these?

To see whether these were at least water-soluble, I poured a small amount of water on one of these peanuts, and it dissolved within seconds. Now that I’ve determined that these packing peanuts are indeed the biodegradable type, it’s time to take the taste test…

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A biodegradable (and edible!) foam packing peanut.

… So, how do they taste?

Perhaps surprisingly, they taste faintly of popcorn; I was expecting them to taste more unpleasant like cardboard, but these had a fairly agreeable yet neutral flavour and I suspect that they can be seasoned with a dry popcorn seasoning with little issue, but they may need a light spray of cooking oil in order to make the seasoning adhere to the peanut.

There are multiple manufacturers of biodegradable packing peanuts (one example is Puffy Stuff), and these are made from some form of starch like corn. However, these packing peanuts are basically devoid of any significant nutritional value, making them less attractive to animals and/or pests. Reference.com says that they are not manufactured under food-safe conditions, and are therefore not recommended for human consumption.

… I’m still going to eat these anyway. 😛 *crunch munch*

Self-discharge test of Kentli PH5 1.5V Li-ion AA (Part 5)

It’s amazing – 894 days (and counting) have elapsed since the start of my long-term experiment, documenting the real-world self-discharge behavior of the Kentli 1.5V Li-ion AA battery… and it’s still ongoing! How have things fared so far?

Surprisingly, even after spending nearly 30 months on the shelf, there is still 12% capacity left. The voltage has dropped from 4.216 to 3.692 volts according to my bq27621 Li-ion fuel gauge; the State of Charge (SoC) has dropped 50% since my last update.

november 28 2017 stats

The linear end date prediction is holding pretty steady, having changed slightly to an estimated 0% charge date somewhere in February 2018.

On that note, I’m impressed by how much attention this little battery has received, even years after my initial review. Every day I see a handful of views checking out the teardown and performance metrics, and there seems to be hardly any sign that this will change anytime soon. To everyone who stops by to check out my blog posts: thank you! 🙂

Mini-Ramble: So… WordAds!

I’ve finally done it – I took the plunge and tried to find out if I can enable advertisements on my blog (*gasp*) through the WordAds program – and as it turns out, yes!

Given what I’ve seen online, WordPress has always been vague on one of their acceptance criteria: views per month. They state on their own FAQ that they require “thousands of pageviews each month to earn meaningful revenue”. There were no clear answers from other bloggers either. In my case, I’ve had a paltry 8,000 views/month on average ever since I registered my domain, ripitapart.com (I had over 10,000 views/month when I was using the free WordPress domain). Given that I tend to blog about relatively niche topics (who really cares about battery fuel gauges, anyway?), this is not particularly unexpected; this isn’t helped by the fact I haven’t been posting frequently as of late (so far I have dozens of draft posts, with some that probably won’t be completed as they have essentially gone ‘stale’).

Application for WordAds

I submitted an application request for the WordAds program on November 20, 2017. Immediately after filling out the form I was given an automated message that I was initially declined due to insufficient viewership (but they would keep my request open until I had achieved enough page views per month). However, the next morning I awoke to an email that read “Welcome to WordAds!” – a pretty nice way to start the day. I’m guessing that the number of outstanding applicants were low, and that my content is original enough to warrant acceptance into the WordAds program. Perhaps there is a manual component to reviewing these applications?

So, what about earnings?

Given that it hasn’t even been a week since I was accepted into WordAds, it’s far too early to say how much I’ll actually get out of these advertisements; on that note, since I use WordPress’ Free plan/tier, there were always advertisements on my site (I didn’t get any revenue from those ads, however). Given how most people likely use an ad blocker (myself included), this will further reduce the amount of revenue I can generate from this blog. WordAds will only pay out advertisement revenue when earnings accumulate past $100, which means I won’t actually receive anything until that point… and who knows how long that will be.

Unlike other advertisement platforms, I do not get real-time analytics of ad traffic, and statistics for the month are only updated near the end of the next month (in my case, this means I will not see any information on November’s earnings until the end of December). One common complaint about WordAds is the lack of customization for ads that will be shown; on the flip side, the advertisement system does all the back-end work so I don’t need to lift a finger in that regard.

Your thoughts?

This is the first time I’ve ever tried online traffic advertisements and site monetization, so saying I’m inexperienced in this field is a bit of an understatement. However, I’m curious as to where this will go, and how this will affect my reader base.

What’s your experience with ads on my blog? I’d love to hear your comments on it, especially as time goes on.

Domain Get… again!

Another domain? You betcha!

My blog is now also accessible at http://jasongin.com. There isn’t any real different content if you follow the link; it just links to my normal domain at http://ripitapart.com.

But why another domain?

In a nutshell, it’s for the ability to register a more professional email address for work-related use (think resumes and so on). Coupled with WordPress G Suite integration, this allows me to easily create an email address that is truly unique (since a similarly named Gmail address has already been taken 😛 ).

The cost isn’t too high, about $100 CAD for a year’s worth in subscription fees.

Now, for formal communication, I am reachable at jason.gin@jasongin.com but any other conversation should be directed towards my personal email, ginbot86@gmail.com.

Self-discharge test of Kentli PH5 1.5V Li-ion AA (Part 1)

As an extension to my previous performance analysis of Kentli’s PH5 Li-ion AA battery, I fully charged an unused PH5 and left it on my desk to self-discharge. Every now and then, a Texas Instruments bq27621-G1 fuel gauge is hooked up to the Li-ion battery terminals (in the case of the PH5, the recessed ring around the 1.5V terminal) and the bq27621’s default settings are used to measure the voltage and state of charge.

I started this test on June 18th, 2015 and will keep taking occasional measurements until the protection IC in the PH5 shuts down.

Since the 18th, the voltage dropped from 4.216 volts down to 4.192 volts as of July 6, 2015; the bq27621’s State of Charge reading remains at 100% for the time being. The voltage drop has been fairly linear so far, but I expect it to taper off as the battery discharges to the Li-ion cell’s “flat region”, and only after that do I expect the cell’s voltage to decline more rapidly.

Ramble/WordPress auto-post time: 2014 in review

The WordPress.com stats helper monkeys prepared a 2014 annual report for this blog.

Here’s an excerpt:

Madison Square Garden can seat 20,000 people for a concert. This blog was viewed about 66,000 times in 2014. If it were a concert at Madison Square Garden, it would take about 3 sold-out performances for that many people to see it.

Click here to see the complete report.