Hi, I saw in the ABB manual that in one example, the robot (one of the hex’s) uses on batery to power both. in an other example, it uses one 7.2 volt to power the SSC-32, and a 9 volt to power the logic on the ABB and the SSC-32.
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Sam, thanks
Logic powers the electronics. The other battery, if it’s not running both, provides the power needed for the servos. Sometimes the logic is run off a seperate 9-vot battery because some of the electronics (like the SSC-32 board) will stop running when the battery starts to get low, even though the servos would still run fine.
You could power the ABB with only logic, but you can’t run any servos directly off it. This is helpful for programming and working on stuff not requiring movement (like how I’ve been working on the PS2 controller part of my program.)
For a biped, it can be a tossup. There is the issue of added weight, especially if you’re looking into the BRAT biped unit. I have yet to recieve my BRAT, so I can’t help you there.
I’d recommend using seperate logic and servo batteries for the initial test purposes.
A 9V alkaline battery won’t set you back, cost-wise, and it won’t be a weight issue while your still learning how things work, since your bot probably won’t be walking at that time.
After that initial (and sometimes very frustrating) learning period, it’s simply a matter of opinion whether or not the weight is worth it.
I didn’t think it was on my bot.
The low dropout regulator on both the ABB and SSC-32 is of the average variety that drops out a maximum 1V (although it’s usually quite a bit less than that).
If you’re using a 6V battery, this doesn’t give you a very large run time.
If you go with a 7.2V pack, though (provided your servos can handle that), then you’ll experience this less.
It also allows you to split which power supply is powering the logic (basically the ATOM, stamp, etc) and the servos. This is sometimes used to prevent the heavy switching that goes on in the servos from adversely affecting the more delicate electronics that makes up the ‘brain.’
To move a servo 90 degrees from dead stop, or even worse have a routine that makes it fly to left 90 then fly right back to 0, yanks a considerable amount of current (and in the second examples, reverses it quickly) which sometimes isn’t friendly with the low power electronics.
For an example you might be familiar with, you ever sit down for a while then get up suddenly and get dizzy (slight vertigo)? That’s a similar, biological situation.
I don’t have the board in front of me but I think the two grounds are connected on the board.
