Yes. The values were chosen so that if I sum 10 ADC samples, the resulting value (plus a calibration offset value) is the battery voltage in millivolts. The voltage divider is driven by a processor pin (not directly off the battery) so that it can be turned off when not actually measuring the battery voltage… considerably reduces the driver parasitic drain.
Not enough pins on the processor for addressable LEDs…
There is a pin on the processor that is used to power strobe the battery voltage divider. It blips every 0.25 seconds when the light is off and at 60 Hz when it is on. One might be able to cobble a status LED onto that pin. I don’t know if the pulse width is wide enough to be visible…
It is rather difficult in the ramping modes to stop at the setting that is moon mode… the next tick up would be another 10 lumens. There are now two ramping modes available. Slow mode ramps up/down over 4 seconds and includes every available PWM value. Fast mode takes two seconds and skips every other PWM value.
I tried to put a 6 pin ISP header on the board, but there is no room.
It turns out all the pins required for ISP programming are available on easily accessible/solderable pads on the board. You could cobble a short ribbon cable with a 6 or 10 pin ISP connector to those pads. I think there is enough space in the SRK driver compartment for the cable.
> It is rather difficult in the ramping modes to stop at the setting that is moon mode…
That's why I usually add a pause at the lowest and highest level.
I sort of do that… I blip the LED at the ends of the ramp. I could make it a bit longer of a pause/blip.
YES PLEASE!
I will be in for one if you make these available.
Will be watching this thread!
Looks very promising! 
With this and copper stars, the SRK should be the chinese lumens rating by a healthy amount and the potential for much more with stacking. 
I got the first cut of the boards in today, but probably wont assemble them.
I changed the layout some to move the regulators inward a little so they wont hit the walls of the driver cavity on some versions of the SRK.
I also made those vias/drill holes in the power ring a bit bigger. The increased surface area of the new via walls should be able to better handle the current.
I also made the board around 0.4 mm wider so that it can be press fit into the head… the first board (and original SRK driver) turned out to be too small to press fit. If the board to too big for your SRK, it can be sanded down some.
The code for the processor is looking good. The random strobe is nasty… I also added a way to select the alpine distress beacon mode. It does not appear in the default mode list since those 10 and 60 second pauses in the flashing might make the typical user think something is wrong when that mode is selected (hey, I got one blip and then the light shuts down). To get the alpine mode you have to program the light. If you attempt to store the OFF state in the user mode list, that mode is stored as the alpine beacon mode (OFF is automatically/always made the first mode in the mode list).
Way to go pyro! It looks like you’ve planned for most contingencies and built a really robust versatile driver.
pyro, this is awesome! We need to bandy together the ‘BLF development team’ to make the 17mm boost driver a reality. 
Just imagine, “the blf triple boost SRK driver”.
Might it be easier to also do a boost driver that can do 6v for mtg2 or the voltage for 3/4 xmls or xml2’s?
4P is a nice setup, and its looking like most of the 4p stuff is fairly interchangeable
That’s another awesome SRK driver. Thanks for the giving us the details here.
I really think that everyone underestimates the size and complexity of a high ratio boost converter… I’m not saying it’s impossible, but it’s not a 20 minute hobby project either… The Ipk currents get staggering pretty quickly with high ratio boost, and all of the components in the switch loop have to be sized to handle them.
Inductors that can handle the Ipk of the type of driver you’re talking are just not ‘small’. For the most part, neither are MosFETs that can handle these current levels. Even the Diodes get bigger… Boost needs a sizable output cap… Everything takes up precious space.
I wish the ‘BLF Development Team’ luck, but I’ll be a bit surprised if a single board 17mm driver becomes a reality that can do 4A in boost mode…
PPtk
Thanks for the input PPtk. I don’t want to derail pyro’s thread, so I’ll quote you in the driver ideas thread.
this is awesome!!
nice job Texaspyro, looks very tidy! I’m always impressed by the ease with which people design these drivers. I’m also really interested by how you implemented temperature monitoring, as that’s something I’d really like to do at some point. As above, I appreciate that you might want to keep your code to yourself, but if you did feel like releasing it, even just the part for temp monitoring, it’d be hugely appreciated! Even if not, I’ll have to bug you once I’m up to speed on programming on how to tackle it.
I’d also second the request for a mid-discharge warning - the pulse from current drive level to 50% of that a couple of times would be plenty sufficient. Obviously it’s utility will vary with the batteries that are used, but it’ll still be useful.
Owning a SRK with a horrible PWM low, and a high mode that cooks the unit after a few minutes - I’d love to get hold of one of these drivers, either as a bag of components or a fully assembled unit.
Thanks TexasPyro.
P.S. After lurking for a while, signed up to BLF just to subscribe to this thread!
STL
There is a feature in the code to gracefully slew the PWM level when changing modes (instead of just jumping to the new level). I’m not sure if it should be enabled… it might make identifying that you are in a ramping mode a little confusing (even though it is faster than the ramp modes).
Speaking of ramping, should the ramp start at the current PWM level and ramp up or always start at dim and ramp up or start at max and ramp down? At the end of a ramp cycle, the direction reverses, it blips the light, then it repeats ad nauseum. Currently, I have it starting at dim and ramping up.