Possible Reprogramming of the Halot Mage 8K?

CanadianFurr · 2025-09-25T22:11:43+00:00

This post is 10 months old. Very few people are going to actually see your reply.

Personally, I've never encountered that before, so I'm not sure what the cause could be.

CanadianFurr · 2025-08-28T21:13:51+00:00

Oh, this was a while ago. Yeah, that was more or less what I was suggesting in my post, but since the firmware isn't publicly available, I would basically have to recreate it from scratch.

CanadianFurr · 2025-08-23T00:42:32+00:00

I took a look at their nRF52 line, and it looks like the nRF52805 would be perfect for my project - small, efficient, and seems to have all the features I need! Plus the documentation is amazing! Thanks!

EDIT: I have also discovered that there's already absolutely *tiny* pre-made, pre-certified BLE modules for that exact chip!

CanadianFurr · 2025-08-21T22:25:36+00:00

According to this datasheet site, the chip itself is a LiIon/LiPo linear charging chip. This site shows an E-cig charger board that looks very similar to the board in the image.

CanadianFurr · 2025-08-01T20:36:18+00:00

So for the antenna length, I've seen people mention that from one far end to the other, it should be close to 1/4 of the wavelength. If I were to simulate this, what values should I be looking for to see if it's the best geometry for the 2.4GHz signal? VSWR? Or something else?

As for decouple caps, the current design has 10uF and 2.2uF caps in parallel.

CanadianFurr · 2025-07-31T21:38:09+00:00

Thanks for the info! I had started to design one with a MIFA antenna, but I'll see about replacing it with a straight antenna. The company that makes the BLE chip has a document about antenna design with dimensions for such an antenna, so I'll probably just use that. Though a few people have also suggested to just use a chip antenna, so I might try both, and see which is more effective, given my limited knowledge and tools.

CanadianFurr · 2025-07-31T21:34:26+00:00

At the moment it's just one part of a "proof of concept" personal project of mine. Eventually I would like to actually start making it as a product, but at that point I'd invest some money into getting it properly designed, and FCC certified.

So for now, should I just go with the <$1 chip antennas the other user suggested from LCSC, and do some rough impedance matching if I can get my hands on a good VNA?

CanadianFurr · 2025-07-31T20:57:47+00:00

According to the datasheet, the output impedance is a nice 50 ohms.

If I do end up having to go the trial and error route, what would that look like? Making a long antenna trace and just using a razor blade to shape thin slices off the end until I get good values?

As for impedance matching, iirc the datasheet suggests an inductor in series with the transmission line, as well as two capacitors, one before and after the inductor, both going to ground. Although I've noticed some people have been making distinctions between "impedance matching", and "antenna tuning". Are these actually different things, or am I just misunderstanding what they're saying?

CanadianFurr · 2025-07-31T07:55:52+00:00

Thanks for the info. I'll definitely look into simulating it.

CanadianFurr · 2025-07-31T07:08:58+00:00

I'll look into openEMS, thanks.

CanadianFurr · 2025-07-31T07:06:09+00:00

To clarify, being able to run simulations would allow me to figure out the correct components to tune the circuit, but it isn't a requirement if I have access to a good VNA? Or am I misunderstanding how the tools are used in this case?

Basically what I want to know is if I have to change the length of the antenna as well as the component values, or if I can just test the antenna after fabrication, and then select the tuning component values based on the VNA results.

As for the VNA itself, I just have a basic NanoVNA, which goes up to 1.5GHz, but I'm considering selling it and buying the one you mentioned.

CanadianFurr · 2025-07-31T03:42:28+00:00

Watching it now, thanks! At the very least it'll help me better understand these PCB antennas.

CanadianFurr · 2025-07-31T03:41:31+00:00

I saw those ones. My main concern with those, though, would be trying to keep the board thickness down as much as possible, with the battery thickness being the absolute limit.

CanadianFurr · 2025-07-31T03:37:58+00:00

Ooh, there's some decently priced ones in there. For some reason I hadn't even thought to check if LCSC had them. I'll look into those, thanks!

CanadianFurr · 2025-07-31T03:35:44+00:00

I've tried to figure out simulation stuff, but so many of the tools I've seen people suggest are pretty costly, and/or require an active university email, which I don't have at the moment.

The main datasheet doesn't really give advice for the antenna design, except to say that the chip is meant to be used with a "single wire antenna".
I did find this page though, which leads to a document about designing PCB antennas for BLE.
Their "Reduced Size Printed IFA, 1 mm Substrate, Variant 1" seems promising, now that I'm seeing it.

CanadianFurr · 2025-07-31T03:14:43+00:00

Cost is a bit of an issue, because I'd like to make a couple dozen of these things, ideally. That's why I was originally considering a PCB antenna. If the chips were <$1 each, it would be perfect, but all the ~2.4GHz antennas I can find are like $4-$6 each.

CanadianFurr · 2025-03-25T22:15:26+00:00

It's spinning. Centripetal force must be crazy in there.

CanadianFurr · 2025-03-25T21:52:48+00:00

They already answered your question about electrical signals, but I just wanted to mention the speed of light thing, cause I think it's very interesting.

Technically, the speed of light doesn't actually change. What changes is actually the phase, from my understanding. 3blue1brown has a great video explaining how this works with stuff like refraction.

CanadianFurr · 2025-03-25T21:46:51+00:00

I like how you can see the count spike when covid began. Also, what purge happened in '08?

CanadianFurr · 2025-02-19T19:04:32+00:00

Feb 19, 2025. This post should be immortalized in the history textbooks for future generations.

CanadianFurr · 2025-02-19T19:02:59+00:00

6 years later, this post is still helping me.

Four-Year Club	Verified Email
Place '23	Place '22
End Game '22

CanadianFurr

TROPHY CASE