Thanks
You all were very helpful.
Sorry for my n00b questions, this is a lot to take in all at once.
If I were to use the barrel plug and a 9v battery, would that provide “only” 5v to a DC motor shield (via the 5v in/out pin)? The brochure for the shield on this site says:
“Connect the Motors to M1 and M2 connectors and supply +6 to 12 Volts to FEZ Domino board”
The motor driver board makes sense to me, as it has a separate input for external DC power.
Regarding motor electrical noise - if you have 2 power sources (1 for FEZ and 1 for the motors), would that help to keep the power clean for the FEZ?
Once I get my head around all of this, I think I would like to create some beginner tutorials on the hardware. While the programming help might be Freakin’ Easy, if you don’t have a hardware background, then that aspect certainly is not.
This is a have to in my book. The noise produced by any motor can cause you multiple problems.
Brown outs in what not and backlash from the motors.
You don’t really want to power a motor on a 9v battery the battery will die a early life as the draw from almost all motors is way to great for a 9v battery.
Just please make sure if you are going to power a motor from the fez output you put protection in your circuit. If not its a matter of when not if you will have a dead fez.
You say “power a motor from fez outputs”… but it can’t be done as there’s not enough current available for this. So I understand that FEZ controls “something else” that will power the motor, right ? Something like a L293, for example.
In this case, do I need protections and, if yes, where ? I would have thought that the L293 would act as the protection ??? Do you mean I should add optoisolator between FEZ outputs and L293 inputs ?
If it’s the case, then I think that most motor shield would be wrong ? What did I miss here ? :-[
@ bstag - Thanks for the reply.
This is a point of confusion for me:
My plan was to use the battery holder on this site to power my FEZ and using rechargeable AAs, that would yield 4.8v. Would that go to the VBAT IN? This would be ok, since the board has a regulator, correct?
Also, is this correct: I would have to solder this in from underneath since if I ran the wire to the pin, it would block shields from being able to be plugged in.
That scares me - I’ve soldered before, but I worry about frying my FEZ.
Again thanks for taking the time to help.
@ bec a fuel - This is (yet another) point of confusion for me: as the DC Motor Shield PDF brochure says:
“Connect the Motors to M1 and M2 connectors and supply +6 to 12 Volts to FEZ Domino board”
I thought that the FEZ would only provide 5v. But then again, my understanding is rather limited.
Motors draw a lot of power and do not require regulated voltage so using regulated 5V is a bad idea. This is why the motors are powered directly from the input, not from 5V not from the USB cable.
I think that in this case, the shield is using the Vin pin, which outputs the same voltage that is applied to the Domino (via the power jack).
Edit: Gus first ! 
So is the VIN is a pass through only? Or would that provide 5v+ power to the shields and 3.3 to the FEZ?
For example, if I wanted to use 1 power source for my bot - let’s say for discussion’s sake a 9v 2400mAh Li-Ion or the like. So then would I have to solder: (1) the “red” wire to the VIN pin and (2) the “black” wire to the adjoining Ground pin to the on bottom of the FEZ board?
Thanks for the help - my fuzzy FEZ picture is slowly getting clearer
No need to solder, just plug in power in the power connector.
Ok great.
Thanks for the help - this is why I’m getting a FEZ vs other solutions. The help on this forum is exceptional.
After some thought … one last set of questions on this - I promise 
So my desire is to have 2 battery packs:
-
9v pack for the motors - using the Motor driver board - with the power connected to that board, (the one using the 6xJST to connect to the Domino). This seems rather straight forward to me.
-
the 4 AA battery pack on this site, using rechargeable batteries, for the FEZ.
With this, can these be plugged into the Power Connector, even though it’s < 6v (4x 1.2v)?
If not, how would I connect it while leaving the connectors open for shields to attach?
Thanks again ever so much - I appreciate your patience. I’m coming from a programmer’s background and not a h/w guy.
I think you could have problems if you run a FEZ off less than 6V into the power connector.
The 5V regulator needs more than 5 volts to perform it function. With 4.8V into a 5V regulator, you will not have regulated 5V power. If you don’t need the 5V for anything, then it might be ok.
I’ve attached an image of what I was planning on doing.
I think I’m good to go on everything except for the power source for the Domino. My plan was to use the battery holder on this site with rechargeables - so I’m not tossing a bunch of batteries every so often.
But they are only 4.8v instead of the 5. I can get to 3.3v by using the 1x1.2 and the VPack3.3V from Bodhilabs.com or to 5.0v by using their 2 AA pack.
On that site they show an Arduino with their power pack connected to the shield connector. I’m guessing I’d have to solder on the leads to do this and still be able to use a shield.
But I’m thinking this will have a decreased run time, due to the sensors, the motor shield and the setup regulator vs having 4 AAs connected.
Thanks
[quote]You say “power a motor from fez outputs”… but it can’t be done as there’s not enough current available for this. So I understand that FEZ controls “something else” that will power the motor, right ? Something like a L293, for example.
In this case, do I need protections and, if yes, where ? I would have thought that the L293 would act as the protection Do you mean I should add optoisolator between FEZ outputs and L293 inputs ?
If it’s the case, then I think that most motor shield would be wrong ? What did I miss here ?[/quote]
Bec In the case of L293D you do not as it has built in diodes to handle that. A L298 would be a different story but the data sheet shows that. I can offer advice for l293d in general though. Put a small cap between the lines driving the motor. try to suggest socketing the chip on the board in the build as they to tend to blow up on some higher draw motors. Also you might want to know you can double stack them so you can get more output. I have seen backlash from the motors blow out the l293d so diodes on those lines may not be bad but more of the case i see is drawing to much current for that size chip. Which normally happens at motor stall.
This being said after i have destroyed many l293d one of my favorite motor control chips.
Not meaning to be a pest, but any responses on my “highly technical illustration” would be appreciated.
I’m wondering in the above configuration, what’s the recommended way to power up the FEZ with 4.8v coming from the AAs.
Thank you all - and I appreciate your patience with me.
(this is all apart of my due diligence, since I’m not a hardware guy)
I tried to understand what you need and I am lost trying to help.
So, you want to connect 4.8V to domino? You can do that easily, just connect the 4.8V to the 5V pin on FEZ Domino and all will work fine
Thank Gus for the response.
I thought that someone else said (forgot who) that since 4.8v < 5v, so the regulator would have a problem with that. This confused me a bit, since the board only needs 3.3v.
Going with that the 4.8 is ok - I do trust you - would I need to solder it to the bottom of the board to allow the shields to still work?
If so, then I may wind up going with the “simple” route and just using the barrel adapter and provide something between 6 & 12v. Also, I would wind up getting the Motor Shield instead of the separate Motor board.
Once I feel more confident soldering a board - like putting a cap on the IR - then I may return to this.
Thanks again - I just got funding approval from the Family Budget Coordinator (aka wife) 
so I will submitting my order very soon!
You are not connecting 4.8V to the 5V regulator…you are bypassing the 5V regulator and connecting the 4.8V to the 5V power signal 
Oh ok. I figured that since the board runs on 3.3, there would be a regulator involved to take the 4.8v (or 5v) down to the 3.3 required.
So my final question is - do I need to solder this on?
Should be obvious, this is a bit scary to me, as I don’t want to fry my precious FEZ, due to my inexperience. I can picture either shorting something, or melting the adjoining pin and the solder joining together from those 2 pins.