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FLIP Pendant
ATIoNo Posted: 15 Jan 2025, 03:43 AM
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 My second favorite project after the precision clock. Would've loved to have gotten my hands on one, but I came in 11 hours too late it seemed.

I believe the video presentation was also one of your longer ones, though half as long as the UV pendant video. Lovely job on all parts of the project, as usual.

I dug through git.mitxela and github, but found no project files. Is this project something you'll consider sharing? Am I badgering you before you've gotten a chance to publish? Either way, I would absolutely love to give producing one of these a go, hope it's not too near and dear to your heart.

Lovely confluence of all you like to do. Regards.

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Dunkle Posted: 15 Jan 2025, 05:15 PM
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 I also want to know its specific details. I plan to use STM32, MPU6050, and 16 * 16 WS2812 for production

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SapereAude1490 Posted: 16 Jan 2025, 11:07 AM
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 From the blog post:

"These demos, along with the source code to the pendant itself, are not yet released to the public, but I plan to do that at some point in future. I figured that at least for a short while, given that I've put some of the pendants up for sale, there should be some mystery behind their exact operation, but all will be revealed in time."

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Tonyp56 Posted: 17 Jan 2025, 08:58 PM
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 How much to purchase the pendant from you?

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Slashasher Posted: 11 Apr 2025, 04:52 AM
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 Any update on if or when the files for this project will be shared? I plan on taking the original design and morphing it to a credit card sized format.

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mit Posted: 14 Apr 2025, 08:36 PM
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yeah whatever

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QUOTE (Slashasher)
Any update on if or when the files for this project will be shared? I plan on taking the original design and morphing it to a credit card sized format.
Probably at least a few months sorry.

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Lestat Posted: 29 Apr 2025, 11:02 AM
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 here and waiting lol i just need to know the cap / res and mayve the code for the chip but i have a pcb ready to go i think

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MrFastfinger Posted: 30 Apr 2025, 11:49 AM
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 I really liked your project and decided to create something similar for my engineering thesis.

As far as I understand, it's not possible to update GPIO pins using DMA on the STM32L4xx series.
It works on my STM32F103, but not on my STM32L467RG.

How did you manage to make it work?

I implemented the display using two 4-bit decoders instead of using Charlieplexing. This way, I don’t have to deal with tri-state outputs — I just need to update the GPIOA register.

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mit Posted: 1 May 2025, 10:27 AM
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yeah whatever

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QUOTE (MrFastfinger)
I really liked your project and decided to create something similar for my engineering thesis.

As far as I understand, it's not possible to update GPIO pins using DMA on the STM32L4xx series.
It works on my STM32F103, but not on my STM32L467RG.

How did you manage to make it work?

I implemented the display using two 4-bit decoders instead of using Charlieplexing. This way, I don’t have to deal with tri-state outputs — I just need to update the GPIOA register.
DMA to GPIO is definitely possible on both L476 and L432. The setup is probably different to the F103 though as they have a different number of streams/channels, I can't remember the details. It's also different again on the newer generation of chips with their GPDMA.

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MrFastfinger Posted: 2 May 2025, 10:31 AM
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QUOTE (mit)
QUOTE (MrFastfinger)
I really liked your project and decided to create something similar for my engineering thesis.

As far as I understand, it's not possible to update GPIO pins using DMA on the STM32L4xx series.
It works on my STM32F103, but not on my STM32L467RG.

How did you manage to make it work?

I implemented the display using two 4-bit decoders instead of using Charlieplexing. This way, I don’t have to deal with tri-state outputs — I just need to update the GPIOA register.
DMA to GPIO is definitely possible on both L476 and L432. The setup is probably different to the F103 though as they have a different number of streams/channels, I can't remember the details. It's also different again on the newer generation of chips with their GPDMA.

I've been trying to get it to work since your reply. I found out it might be possible using DMA to write to GPIO->BSRR, but I couldn't get it working. I think I still need more experience to pull this off.
In the meantime, I optimized my simulation parameters, and now it runs decently on my F103. (I also overclocked it to 128MHz...)

Last edit by MrFastfinger at 2 May 2025, 10:33 AM

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Jos Posted: 27 May 2025, 06:10 AM
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 Hello, I followed your suggestions and built a prototype, but encountered some issues. After adding collision detection, the refresh rate became too slow and the screen appears too dim. Have you performed any overclocking?
Regarding DMA usage:
- I'm only using DMA to control GPIO output levels
- I'm not using DMA to change GPIO input/output modes
- Could DMA also be used to control GPIO modes?

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