I'm afraid this is a bit of an epic post but I thought I would post this to warn others, and to try and save other people from hours of frustration and troubleshooting that I ended up going through before I finally discovered the cause of the problems I was experiencing.

For those that don't have time to read this (very) long post or can't be bothered, a summarised statement is that FrSky seem to be shipping out Taranis X9D+ transmitters, some (or maybe all) of which contain a fake capacity 1GB SD Card. The result is that files and folders on the SD Card start to become corrupt as additional files are added to the card and this completely screws up the OpenTX content on it. I don't know if this affects other FrSky transmitters but if FrSky are using the same SD Card supplier for all their transmitters then the likelihood is that it probably does. It makes you question what sort of dodgy component suppliers FrSky are using and why their quality control process is seemingly not up to scratch. FrSky have been made aware of this issue but they had no comment or explanation to give, and no apology to make. Shame on them.

For those that want to read on, there is a step-by-step guide complete with pictures further down the page to help you determine whether or not you have a fake capacity SD card in your FrSky transmitter. That guide is specifically aimed at the Taranis X9D+ but the same procedure can most likely be applied to other FrSky transmitters that contain an SD Card.


Background Story

Last week I spent the best part of a whole day trying to update the firmware of the X9D+ and corresponding content on the SD Card. The flashing of the firmware itself was always successful and I was also able to copy the associated content onto the SD Card with everything appearing to work fine after then powering the X9D+ back on. However, whenever I tried to copy additional files to the SD card (in my particular case, Betaflight Lua Script files) and then power the X9D+ back on, it would complain about the version of the content on the SD Card being incorrect for the installed version of the firmware. Further analysis revealed that the opentx.sdcard.version file in the root of the SD Card contained corrupt data, as did the BF folder.
 
I wrongly assumed that the issue was being caused by some kind of problem with the bootloader and/or firmware and/or the Lua scripts, and spent pretty much all day chasing my tail trying umpteen different combinations of firmware versions each with various different options selected (eu, noheli, lua, luac etc.) in conjunction with different versions of the Lua scripts, but to no avail. Nothing worked and files on the SD Card were still becoming corrupt as soon as I added the additional Lua script files.
 
I was almost ready to accept that my XD9+ was faulty when I then had some common sense to actually check the integrity of the SD Card. I ran a number of tests on the card and the result of these tests confirmed that the supplied "1GB" SD card was a fake. On the outside of the card it is stated as being a 1GB class 6 card, but the reported internal capacity of it is showing as 1.87GB or 2014MB (both of these values equate to the same capacity). Further testing has shown that files and folders on the SD Card start to become corrupt once data copied to it exceeds 170MB. This means that not only does the card not have a capacity of 1.87GB as reported by the file system, but it doesn't even have a capacity of 1GB as stated on the outside of the card. The REAL capacity of the card is actually 170MB. This is not due to a faulty card, but are known symptoms of a knock-off card which has been purposely manufactured to appear to have a larger capacity than it really does. The files and folders become corrupt because once the real 170MB capacity is breached, the file system then starts (over)writing data to sectors on the card that are already in use by other files.
 
I managed to find a verified authentic 2GB SanDisk branded SD Card in the back of my drawer from an old phone. After formatting this in the X9D+ and then copying across all the correct content files to it for the installed firmware version along with the additional Lua scripts, everything then started to work perfectly using that card with no file or folder corruption.
 
I was somewhat relieved that there was no issue with the X9D+ itself, but am disappointed that a supposedly reputable company like FrSky have been shipping out transmitters with knock-off no-name brand fake capacity SD Cards in them. I am starting to wonder how many others have spent hours of wasted time trying to figure out why on earth the Taranis is complaining about invalid files on the SD Card after doing a firmware upgrade and updating the content on the SD Card. Reputable branded SD cards of the same capacity only cost a few dollars (and even less if bought in bulk) so I don't really understand the logic of FrSky skimping on cost and using no-name generic SD Cards in premium priced transmitters.


Overview of the Issue

The steps below will help you to verify whether or not the factory supplied 1GB SD Card that is installed in the battery compartment of the FrSky Taranis X9D+ is a fake capacity one like mine was. For reference in case this issue is batch or region related, I purchased my Taranis X9D+ SE in May 2018 from a UK based supplier and it came pre-loaded with the EU-LBT version of OpenTX v2.1.6.



Below are photos of the fake 1GB SD Card that was present in my Taranis X9D+ SE and which was reporting an internal capacity of 1.87GB as shown in the adjacent Windows Explorer properties dialog screenshot for the SD Card.

Based on the results of my tests, file and folder corruption starts to occur after data added to the card exceeds 170MB. This means that not only does the card not have a capacity of 1.87GB as reported by the file system, but it does not even have a capacity of 1GB as stated on the outside of the card. The actual capacity of the card is in fact only 170MB.

The serial number printed on the back of the card is AOS2A803F1AE. Counterfeit/fake cards all tend to have the same serial number printed on them instead of unique numbers so if yours has the same number on as this one then the chances are that it is almost certainly a fake card.

  

These are the details of the fake 1GB SD Card when viewing the “SD Info” for it through the Taranis X9D+ interface which show a capacity of 2014MB (1.87GB). This corresponds exactly with the capacity that was reported by Windows Explorer.




Steps to verify whether you have a fake capacity 1GB SD Card in your Taranis X9D+

1. Delete all existing content from the SD Card and then copy new content data to the SD Card (from the relevant zip file HERE or HERE) that corresponds to the firmware version installed on your X9D+. Open the opentx.sdcard.version file in a text editor to display and confirm that it contains a valid version number for the content files on the SD Card:-
   
   
   
   
2. Get the required version of Betaflight Lua scripts (from HERE) and copy the folders from underneath the obj folder within the zip file to the root folder of the SD Card. This will merge the content from those folders on the zip file with content on the SD Card. Some of the scripts will end up under the existing SCRIPTS folder and other scripts end up in a new BF folder:-
   
   
   
   
3. Insert the SD Card back into the Taranis X9D+ and power it on. Acknowledge the throttle and failsafe warnings (if either of those appear). If you are then presented with an SD Card warning message indicating a version mismatch with the same version number stated in the warning message as per the version of the content you copied to the SD Card in step 1, this is a symptom of the contents of the SD Card having become corrupt:-
   
   
   
   
4. Either examine the contents of the SD Card either via a USB cable connected to the Taranis, or by switching off the Taranis and removing the SD Card, then inserting it into an SD Card reader and viewing it through file explorer software. Open the opentx.sdcard.version file in a text editor file and you will immediately be able to see whether or not the original version number that was previously present in it has become corrupt with some other text and/or unicode characters. If so then this has happened because part of another file has overwritten the content of this one, pointing to the SD Card having a fake capacity:-
   
   
   
   
5. Also take a look in the BF folder and if you find a whole load of folders and files with corrupt/invalid files names where there used to be just 2 Lua script files, then this also indicates a fake capacity SD Card:-
   
   
   
   
6. Put the SD Card into an SD Card reader connected to a Windows machine and run the H2testw utility (only works under Windows) which can be downloaded from HERE. This is a defacto piece of software that is used to test SD Cards for read/write performance and fake capacities. If when you run the test you see that numerous errors are reported along with DATA LOST then this is because files being written to the card are being written to sectors of the card that are already in use by other files, thus causing file and folder corruption to occur on the SD Card. This happens because the SD Card is reporting a larger fake capacity than it actually has thus confirming that the card is a fake.
   
   The card that was supplied with my Taranis X9D+ has a reported capacity of 1.87GB but as you can see on the screenshot below it is losing 1.7GB of data during the test which means that the REAL capacity of it is only 0.17GB (170MB). Also, a reported write speed that is the same or faster than the read speed, as per my card in the test below, is highly suspicious. Everything about this card is wrong:-
   
   
   
   
7. Put the SD Card in an Android device and install the “SD Insight” app from the Google Play store which is a utility that can be used to identify counterfeit/fake SD Cards. Then run SD Insight against the card and if the SD Card is reported as being invalid then this is an indication of the SD Card being a counterfeit/fake:-
   
   
   

Heh, had the same exact thing happen with a brand new transmitter, thank you for the write up. Didn't gave it much thought (an unbranded SD card these days generally screams of "so cheap, so fake, we did not even bother to imitate the laser etching"), changed to a 2 GB card and no problems ever since.

Yes. I think the lesson to be learned from this is that if you ever see an SD Card in any device that has no branding on it whatsoever then bin it and spend a few extra dollars on a known branded card from a reputable supplier. Even if the card passes all tests, who knows how reliable a no-name card is going to be in the long term. It's just not worth the risk, even more so in devices where you value the data being stored on it.

Unfortunately I didn't even remove the SD Card from the battery compartment and take a look at it until I'd already wasted far too much time tearing my hair out because I was originally just transferring all files to the SD Card via USB cable to the Taranis.

I can understand counterfeiting of the large capacity SD Cards that can fetch a reasonable sum of money, but what I don't really get is why anyone would even bother to manufacture non-branded fake SD Cards with a "1GB" advertised capacity that are worth virtually nothing these days. Not to mention that it's getting increasingly more difficult to source a card with such a low capacity because no-one really wants them anymore anyway 

And as for FrSky even contemplating making use of such non-branded cards in transmitters that their customers are paying a fairly whack of money for, I think my jaw is still on the floor!

Over time, you learn that manufacturing/shipping/China ways are way too mysterious or absurd to give them much thought. Who knows what supplier contract must be still in place

Thanks for the write up SLF, very interesting!