FET+7135 Driver Question(s)

First, let me say this question set is directly related to a 17mm Lexel driver from a few years back. I would direct this question right to Lexel, but he has not repled to a PM and I notice he has not logged in for 6days. I hope he is well or if not is recovering.

This driver has Narsil loaded, has 7*7135 regulators, and a FET. I have a planned use where I don’t need, actually don’t want, the FET. Just want the 7*7135’s. And I want Narsil, or maybe would reflash to Anduril. That’s not important.

So I fired up the reflow heat gun and removed the FET. (A couple of years ago Lexel made me a pair of special drivers like this; no FET and 4*7135’s. I used one in my SRK based, DBSAR inspired lantern. It works well.) I was hoping for the same performance with this modified driver.

What I have happening with this driver that I removed the FET from, is that it powers up and ramps up/down fine, but when it reaches maximum, the led turns off just after the led reaches the brightest level. I am assuming the firmware is shifting the output to only go through the FET. If I release the button briefly and ramp down the led comes back on very bright and then ramps to ML.

Is that a correct assumption? Is there a way a non-coder like myself, can change whatever needs changing in Narsil or Anduril, and reflash the MCU?

And does anyone know if Lexel is okay or just overcome with whatever is transpiring in his life?

Yes you are understanding correctly I think. On the ramping tables I’ve seen it ramps up to all 7135s then starts the FET ramp, but during the FET ramp it keeps the 7135s all on. This is to make the ramp transition smoother. Only at the very highest mode does it turn the 7135s off and go 100% FET. So if there’s no FET there would be a portion of the ramp near the top that is just constant brightness (all 7135s). But it’s possible your ramping table is different.

To fix, you would need to alter the ramping table, which is not complicated I think, then recompile the FW and reflash.

There’s a no FET firmware floating around, you just need to find a suitable one and reflash it. Would also work without melting chips off.

If you can manage to solder in a amc7135 in place of the fet, it should work but high or turbo would be 350ma. The light would work without having the no light spot.
This is how the amc7135 fet driver originated in the first place. howto: Build a Nanjg-092
The best way would be to flash with a modified firmware though.

You made from 3 channels into 2 channels , you have to re-flash with 2 channels soft… or, maybe , you can try to short signal input of FET and 7135 bank . :smiley:

If you don't find suitable FW and your FW needs are not so complicated I can try write the FW for you

Thanks for the offer YuvalS. Maybe some future help.

I figured out how to remedy my problem.

I have one of the lexel FET+7135 drivers with NarsilM running in my lantern. It was made by Lexel without the FET on my request. No FET, 4 x 7135’s, NarsilM. I like it.

I used avrdude to dump the files from that driver. Then I flashed the flash-dump.hex file to the driver from which I had removed the FET. Voilà! My newly re-flashed driver ramps from low to high without going off at FET-Max like it was doing. Ramps back down.

I still don’t understand the coding but heck, the new light will do as I want. :smiley:

In the past, I have blundered my way into simple code and made some simple changes on some attiny13 code, such as what I used for the blinking tail-light on the 7th O-L contest entry of mine.

If I wanted to see what is inside the code for Narsil or maybe Anduril what would be a good stable file version to download? I may get in over my head but chips are cheap. :person_facepalming:

Thanks all.