Reseting the Juice Meter

[Bobby-H]

👋 Hello, circuit-newbie here! Following the readMe I was hopeful I'd be able to reset the juice-meter of the vape by disconnecting the battery for a power cycle. Hoping to keep potential destruction risk to a minimum i only de/resoldered the ground wire to the li-po; but after reassembly and a test i was still seeing the depleted juice animation. :/
not sure if i should have desoldered both ground & power, but figured i'd ask just incase there was an explanation that'd save me any unwarranted soldering.

[ginbot86]

Unfortunately the juice level is stored in the same SPI Flash that holds the animation/image data, hence why it didn't reset when you attempted a power cycle.

[Bobby-H]

ahhhh i see now. looks like im gonna need a probe!
iirc you used a segger eos probe &or a DSLogic Plus analyzer? - both of which look robust. another less costly (potential) option that surfaced was this open source 'jeff probe' ?
i know im out of my depth, i've never used a probe before; is it fair to ask if this would this suffice for accessing and editing firmware?
or if there's a comprehensive learning source for newbies like me just getting started, i'd do due diligence to learn - i just don't want to nag and beg for hand holding 😅

[ginbot86]

I'm using a Segger J-Link EDU but those are still pretty pricey. The DSLogic would be the wrong tool since it can't do any debugging on its own; it just passively listens for data.

I actually haven't heard of the Jeff Probe. Looking online, it appears to be based on the Black Magic Debug, which should support these microcontrollers. You'll still need to build your own debugging cable though, since you'll need a USB-C cable that brings out power and both CC lines.

Editing the firmware would be a pretty tough task, but technically doable with enough experience with tools like Ghidra. Editing the image data is a lot easier with tools like PixelViewer. I don't have any specific guidance to give for firmware debugging and modding myself, but I'm sure there's plenty of tutorials out there.

[Bobby-H]

Thaaaank you for steering me clear of buying something that's read-only!
Not sure if it matters but i'll mark that as the answer. From here i'll just look at anything comparable to the segger j-link edu and maybe further inspect the potential process for building a debugging cable. I'll aim to circle back with what i buy - potentially as a beginner recommendation if im successful in erasing the bytes from locations 0xF8000-0xF8004

[ginbot86]

Another project on GitHub has some Python code to automate the SPI Flash editing, including flashing new images and editing the vape juice counter: https://github.com/xbenkozx/RAZ-RE

It'll probably be a lot easier to use this with a GDB server than learning how to manually twiddle the SPI controller registers, then sending SPI Flash commands to edit the data. It would be a very worthwhile learning experience to do it, though.