Schematic and PCB for the $50 Robot

[Soeren]

Hi,

There seems to be some that are missing a schematic and/or a PCB for the $50 Robot, so here's a file that should help:
http://That.Homepage.dk/PDF/$50_Robot_SCH_OVL_PCB.pdf

Even if you don't need it, if you've got the eyes for it, please look it over to see if there's any apparent blunders.
Anything you'd like to see included, please tell me and if sound, I'll consider it.

The PCB(s) may look "funny" when inspected on-screen unless the zoom-factor is upped to at least 200%, but it will print just fine in 100%.

Admin <- If you like, you are welcome to include it on the project page (although it might be wise to wait for any eventual error corrections )

[galannthegreat]

Sweet Soeren, thanks for posting this one up. I'll take it to my class tomorrow and see if I can get a prototype made on the rapid protoyping machine, just to test things out. I'll report back as soon as possible.

[Joker94]

Great job Soeren, from first glance it all looks good.

For the final confimation we'll wait to see how galannthegreat goes tomorrow.

And i think it is a good recource to have on the $50 robot page as alot of people can make pcb's and would like to have a pre drawn track to use.

[Soeren]

Hi,

After I posted it, I realized that there have been a lot of talk about using two batteries (9V and ~4.8V).
Is there a need for two battery connectors?

Personally, I'd think a 5 cell NiMH would be able to handle both being regulated with an LDO regulator (if run down to no lower than 1.1V/cell) and the Servos.
5 cells would have a charge termination voltage of around 7.25V, but will quickly drop to around 6.75V when removed from the charger.
When loaded, the voltage should stabilise at 6.25V max.

Another option is a switching regulator (either buck or boost), but what do people think?

[galannthegreat]

Would you by chance be able to post up a gerber file, that would make the process way easier.

[Admin]

Hi,

After I posted it, I realized that there have been a lot of talk about using two batteries (9V and ~4.8V).
Is there a need for two battery connectors?

Personally, I'd think a 5 cell NiMH would be able to handle both being regulated with an LDO regulator (if run down to no lower than 1.1V/cell) and the Servos.
5 cells would have a charge termination voltage of around 7.25V, but will quickly drop to around 6.75V when removed from the charger.
When loaded, the voltage should stabilise at 6.25V max.

Another option is a switching regulator (either buck or boost), but what do people think?

My vote is for single voltage supply. Its easier.

Also, soldering single 3 pin male headers are a pain to get aligned correctly. I recommend doing them flush like on my Axon.

Lastly, include a separate 6-pin ISP header connection. 10 pin programmers are becoming obsolete.


edit: fixed typo

[Pierre]

Great job Soeren

     The PCB looks great. 

     May I ask what software you used to make the $50 Robot PCB.  I see that the end result is in PDF.   

P.S.  Just finished last night the controller board with the old fastion soldering. 

[Soeren]

Hi,

Would you by chance be able to post up a gerber file, that would make the process way easier.

Put it to work last evening, but when I had to close down for the night, it hadn't finished (due to the ground polygon).
I just came home from a dinner party and am running the post processor now, but it hasn't even begun on the ground plane, so I fear I won't be able to finish it today either. Tomorrow I'm taking my SO to a movie, so... But if you have some patience, I'll get it done.

Personally, I make a LASER print on a good quality fairly heavy drafting paper and use that as a film for photo processing of a pre-sensitized PCB - works every time

[Soeren]

Hi,

My vote is for single voltage supply. Its easier.

Noted.

Also, soldering single 3 pin male headers are a pain to get aligned correctly. I recommend doing them flush like on my Axon.

I'm not certain about what you mean by soldering them flush. I do know the semantics of the sentense, but flush with what? I studied the photos of your Axon but didn't get any wiser.
Even though it's shown as 3 pin connectors, I'd recommend using 3 long strips laid the other way, as it is far easier to solder them that way, perhaps that's what you mean?

Lastly, include a separate 6-pin ISP header connection. 8 pin programmers are becoming obsolete.

Wouldn't it be better to use just the 6-pin connector then?
I assume there's a standard pinout for that I should follow - anyone has got a link to such a pinout?
Or should it just be what gives the best/easiest layout?

[Soeren]

Hi,

May I ask what software you used to make the $50 Robot PCB.  I see that the end result is in PDF.   

Thanks, it's made in Cadsofts Eagle.
The end result is just my way of gathering the output files - a great way to keep a project together and to make it useable to everybody.

[galannthegreat]

I am asking about the gerber file because I have access to a prototyping machine that could very easily make this board within minutes, and the software would either require me to have an UltiBoard file or a gerber file. I don't mind waiting awhile for it... I've got some of my own projects that I'm CADing up for the machine.

Thanks Soeren, I hope to be of help in testing this one out.  

[Conscripted]

Wouldn't it be better to use just the 6-pin connector then?
I assume there's a standard pinout for that I should follow - anyone has got a link to such a pinout?
Or should it just be what gives the best/easiest layout?

I found this lurking around the forum. I've used it on both of the hand made boards I have. Works great.

Conscripted

It has an internal pull up, dont worry about that (just dont leave your programmer plugged into it without power).



I think you have the orientation of the programmer pins wrong. You have pin one going to VCC, instead of MISO. Pin two you have going to MISO instead of VCC. etc. etc.

See if that works.
-Buk

[Admin]

Also, soldering single 3 pin male headers are a pain to get aligned correctly. I recommend doing them flush like on my Axon.

I'm not certain about what you mean by soldering them flush. I do know the semantics of the sentense, but flush with what? I studied the photos of your Axon but didn't get any wiser.
Even though it's shown as 3 pin connectors, I'd recommend using 3 long strips laid the other way, as it is far easier to solder them that way, perhaps that's what you mean?

Yeap you guessed right. I meant flush up (no spacing) with each other.

Lastly, include a separate 6-pin ISP header connection. 10 pin programmers are becoming obsolete.

Wouldn't it be better to use just the 6-pin connector then?

yes

I'll probably have to redo the $50 Robot tutorial all over again in ~2 years. Its already showing its age! Stupid march of technology . . .

[Soeren]

Hi,

Next iteration ready now on:
http://That.Homepage.dk/PDF/$50_Robot_SCH_OVL_PCB.pdf
PCB down to 2.4" x 1.5" with the 6 pin connector in place.
As I don't think it will be the final version, the file is pretty rough - just the bare necessities.

Let me know if you spot anything out of order or something.


Conscripted <- Thanks for the pinout, it has been incorporated.

galannthegreat <- It bugs me, but I still haven't succeeded in getting it to spit out a Gerber. I have tried several cam jobs now and I have to admit, that it's getting me to consider taking up watching paint dry as a hobby (I guess it's the ground plane pour that it stumbles upon, but I'm not sure, as I don't use Gerber myself).

[galannthegreat]

No worries about the gerber anytime soon. Nice job on it btw.

By any chance could you tell me what tool you're using to make the gerber?

[Soeren]

Hi,

I'm using the one that came with Eagle (gerb274x.cam) after the "excellon.cam" - followed a tutorial I found on the net to the point.
I also found a place to download a couple of other gerbxxxx.cam which was claimed to be of better resolution, but they wanted registration and I don't care registering for just 2 files. Since they should have a higher resolution, I don't think they'll work through any faster though.

Do you know of any shortcuts to take?

I probably won't be making a PCB myself, since I have no use for it, so if anyone find errors, please say so for the benefits of others.


Another project I might be putting together within a reasonable time (knock on wood) is a SEPIC supply, taking anything from a single Lithium cell or 4 NiMHs to a 4 cell Lithium a 10 cell NiMH or a 12V lead/acid and spitting out 6V for servos and 5V for logic. I think that might end some of the problems with selecting batteries - just pop in whatever you've got (within reason and specs of course).