Awesome contribution to this thread. My question is, what do you mean by the "Toruk Test"?
Thank you again for your assistance!!
Basically, the Toruk Test is... If the Arduino fails, will the blaster still function as if it were stock, or close to?
Thats cool, I had no idea that the arduino could do that. But if I'm not mistaken, it will only show you the 5v or 3.3v rail that the Atmega328 is running on. If you are using an S3 (3 Cell) LiPo battery, then full voltage will be 11.1v. If you run off of any of fewer cells though, you'll still only get as close as 7.4v, or 3.4v. I suppose you could run the MCU off of a single cell of the lipo, but there are a few things you need to keep in mind.
1. A fully charged lipo cell runs at 4.2v, and at maximum safe discharge, it will go to down to 3v. 4.2v may be more than a 3.3v MCU can handle. And 3v may be less than a 5v can handle.
2. Discharging a lipo unevenly (more load on some cells than others) is bad for your lipo. And if you are only measuring one or two cells to determine the battery's overall power level, then you'll be estimating the unmeasured cell's power level. (i.e. if cell one is at half discharge, then I'm assuming cells 2 and 3 are as well.) And while that may work at first, because of the uneven load distribution, you will eventually get faulty readings as the cells deteriorate.
As far as I know, you'll have to regulate the power down from 11.1v to 5v or 3.3v, but if it is regulated, you won't know if the battery is loosing power or not based on the power to the MCU.
If I'm not understanding what you're saying, please let me know because my current understanding says I need to know the voltage of each cell of the lipo individually, in order to properly protect the battery from over discharge. Hence the circuitry to measure the battery's power.
The rest of your project sounds great though. Will you be making a project post on Nerf Haven?
Once all my bits arrive, I'll make a build post both here and on the Britnerf forums. I have already done some stuff using a 3S LiPo to power an Arduino, and I power using full voltage off the JST plug, so I don't severely unbalance the LiPo. I have considered wiring in my LiPo charge meter in parallel so I just have a low voltage alarm, if not a full volt reading. Not sure if it will work.
Already going to be using lots of the analogue pins, I2C display, flywheel and pusher MOSFETs, may use a variable resistor or rotary encoder for changing settings, then digital pins for microswitches and navigation... Might have to lose features if I want per-cell health, knocks out 3 analogue pins right away, maybe just one if I can get a clock to toggle between the three cells once per second or so... I really need to get a sketch of the hardware finalized.
I may just re-use that Lipo and current-limit using the MOSFET to keep the max voltage supplied to the motors at or around 6 volts. Heck, I may make that a programmable feature, along with the dart pusher rate of fire. Got software control, might as well make the most of it.
For my use, powering off the unregulated supply, I will have to see what happens. Those particular pins regulate from 6-20V down to the internal required 5V for my board. This internal regulator will probably stop the function of the on-board voltmeter, as I don't think I can get the pre-regulated voltage using this method.