I'm working on a relatively complex project, that at the end of the day is very compartmentalized - a ton (30) of digispark arduinos, 150 irleds and receivers, external adcs, etc.
I've got pcbs designed and on the way for most of it.
I'm planning on using just one decent-sized battery bank as the +5v/V- for everything, at 5v (regulated down to 3.3v in a couple of cases) and passing +V and -ground through each using the usb on the digisparks in most cases. Basically, everything has a common 5v and common ground. For the +V, it seems fine as the wires can more than handle the amperage I'm putting through, and each chip has its own regulator.
Do I need to have a concern about sharing a common ground for everything overloading something? Am I thinking about this wrong?
As long as each device has it's own regulator, I wouldn't expect any problems. Even without separate regulators, 30 Ardunios probably wouldn't be an issue (as long as the 5V was maintained.) The separate regulators act as somewhat of a filter so that noise from one circuit doesn't affect the others (hopefully).
You do need a fat ground return wire since it will be carrying all of the current.
...Where I work, we connect 20 or so boards (not Arduino) to one power supply for their burn-in cycle. Every time I add a board to the chain, the power supply glitches as a capacitor charges-up and all of the other boards reset. Once they are running they are fine.
Thanks. Each PCB has pins broken out for 5v/-5v, so I can avoid "truly" daisy-chaining them. If my math is right, in total I have a couple amps at max (the vast majority is pulsing so a true duty cycle is likely much less). I do use big fat routing on the pcbs. I know tons of microusb cables handle 500ma and many do 1a - not sure if I can go as high as I want to or not. I'll check the AWG of monoprice cables.
That should work, provided the supply is adequate for the whole project.
If you're switching any large loads, particularly inductive ones (motors and such), you should be on guard for problems caused on that or other Arduinii when these are switched, which might require additional filtering on the supply. Often, people put motors on a separate supply for this reason.
Note that you are not using the builtin regulator if supplying with 5v through the 5v pin (if you supply with 5v through barrel jack, it aint gonna be 5v when it gets to the chip, due to dropout).
Thanks. No motors or large loads suddenly changing states. Just a ton of pulsed irleds and receivers, 2 rfid readers, some 7-segments, a RTC, some IR-rangefinders, and an esp8266, compartmentalized over many multis and microUSB. A racing system. And you're right, I think I am actually forced to daisy-chain, or else I can't get the power from board to board the way I want. I'm fine with some voltage drop - I can use 9v or 12v since the regulators can handle that, and everything I run goes off 5v or 3.3v.
Hi,
Can I make a suggestion, I gather your 5V power supply is just that, 5V between + and - leads.
So you have +5V and gnd, not +5V/-5V, that is a totally different arrangement.
Tom - yes, sorry. It's all just tied to the gnd on the battery. Just pwr/gnd, no negative voltage (whatever that is :p). I'm thinking I'll divide it into 2 batteries just to be safe, as that doesn't change much (can still use small USB battery packs) and can then avoid running any wire across/under the racing lane. Glad consensus here is that daisying the grounds should be OK.
