hmmm…ok, i did find one or two with the 128k listing but now im not trusting any
these are the blue pills sold as 128kb . but they look like are configured like the black pill . no jumpers like the blue pills that have been posted here .
the 5 volt pin on bottom right is the one that should not be connected ? .
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I’ve had success using a blue pill identical to yours, so there shouldn’t be any problems using one that looks like this. 
It’s the 5V pin by the USB connector that shouldn’t be connected (top right on the picture below):
Edit: Proof of success! Thank you @sebastian for putting together the design and documentation.
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thanks for the info , good thing I didn’t get that far before learning about that 5v pin . I am not really up on the Arduino things and was a bit confused , now its on to figuring out how to load the software …
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Article and discussion might be of interest:
This looks like an interesting module but its being based on a microcontroller board that seems to be so problematic to obtain in its correct form puts me off. If for example someone got a 128k board from the AliExpress link posted above, great, but it says 64k in their listing and if you were to order one and receive a 64k board you’d have no recourse. Not a mess I want to immerse myself in. If this project were built around a Teensy it’d be a very different story; you know where to get genuine Teensies with known specifications.
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I travelled this path a while back and almost gave up getting a compatible blue/black pill at one point. I ended up with a bunch of different boards ordered in haste with the hope of getting one of them to work. I ended up with a standard looking black one with the robotdyn branding which reported as being 64k, but worked fine. I also got a bunch of cheap looking APM32 boards which have 128k and work fine, but they have an additional B pin towards the right on the usb jack, with a little pin bending, that once also worked too. You may find the APM boards easier to find.
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Do you still know of the link where you got them from?
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I got them off taobao, but I am in China where it’s the goto for any kind of shopping, I dont think it’s directly accessable outside of China. You should be able to get them from aliexpress.
I just checked my cart and the 2 boards I got at the time, both of which worked are a GD32F103CBT6 (blue) and a APM32F103CBT6 (green and slightly wider)
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Digging this back up…ordering parts for this. Wouldn’t 15k and 30k work or 75k and 150k? Is there a reason why the values have to be around the 25k and 50k range?
Edit: Okay, I see there is that 100k. so you would need a 120k or 600k to get that 1/4 ratio. Would that cause issues? I suppose just going with 24k&51k makes things easier to keep track of.
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They’re using 100k, 49.9k, and 24.9k to get close to 4:2:1 ratios. As said above, since they’re calibrating in software, it’s not at all obvious why 100k, 51k, and 24k wouldn’t be perfectly good. 62k, 30k, 15k would be a little further off the ratios and 62k might be a tad low for the input impedance. 150k, 75k, and 39k also is further off the ratio. 30k, 15k, and 7.5k gives the ratios spot on but I really wouldn’t go for an input impedance that low.
Since you’re ordering anyway you could play it completely safe and just order the values specified, 24.9k and 49.9k and 100k. At Digi-Key they don’t cost any more than E24 values. But then at Tayda they don’t carry those values.
I’d probably go for 24k, 51k, and 100k. And then, quoting myself,
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I’m ordering most parts from Tayda, but the DAC and ADC and some other stuff are going to need to be from Digi-Key and Mouser. Their prices seem to be exponential higher on resistors and I am cheap, haha.
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Ten cents each is highway robbery! For certain values of highway.
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Oh…oops…I double checked, they are cheaper than I realized. Digi-Key and Mouser’s websites stress me out.
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I used 100k, 47k, and 24k, and everything seems to work fine.
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Has anyone built one of these recently? Wondering about the status of the blue/black pill situation!
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it largely depends which IC your blue pill has onboard, if it’s some kind of clone it may not work
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I have had some luck with some 64kb blue pills from AliExpress.
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mine are still on the shelf until I get around to leaning the firmware loading thing …
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I still haven’t gotten mine working. I have tried a bunch of ways of programming the Bluepills (The are supposed to be 64kb, but show up as 128). I don’t know if it’s something I am doing or the chips currently being made aren’t exactly compatible with the firmware. I am not sure I would attempt it unless you are sure you have Bluepills that will work.
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Ahh what a bummer! I might have to bite the bullet and just do a Braids euro>Kosmo conversion