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Topic: Advise for circuit, and pcb layout (Read 16341 times) previous topic - next topic

graynomad

Yes that's the same data sheet I was looking at, honestly life is too short to mentally convert between chips because the wrong model in on the schematic. And I made comment or two you haven't addressed.

If you can produce a readable schematic (hint, look at the schem on page 22 of the data sheet, I don't think your circuit is anything like that but I really can't tell without too much strain on my old brain) and answer the questions I'll look again.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Jak24


Yes that's the same data sheet I was looking at, honestly life is too short to mentally convert between chips because the wrong model in on the schematic. And I made comment or two you haven't addressed.

If you can produce a readable schematic (hint, look at the schem on page 22 of the data sheet, I don't think your circuit is anything like that but I really can't tell without too much strain on my old brain) and answer the questions I'll look again.

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Rob

Hi
Working on the new schematic,
so you suggest I create my own eagle part for the BTN7971B ?
And also I am not 100% sure why the resistors are "indecipherable"
I tried cleaning It up a bit, I have attached a pic of the work in progress, hope its better
and I also attached the schematic which I based my design on, hope that helps as well.
Thanks

CrossRoads

Yes, create a new symbol.
Also try a search at newark.com for  BTN7971, they often eagle symbols that one can download after registering & then logging in.
Unzips as a script file.
In eagle control panel, open a new library, run the script, save the resulting symbol.

The way you drew it up is just a mess.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

wes000000

The redrawn one is still pretty messy. For example the junction between pins 7 are overlapped on top of the IC.

I would work on a new symbol and try and move the schematic wires around to get rid of all the junctions and wires running through the ICs themselves.
"I have not failed. I've just found 10,000 ways that won't work." - Thomas A. Edison

graynomad

That schematic is just plain wrong, it does not match the reference at all as far as I can tell.

The "indecipherable" resistors on you schem are connected between the control signals, on the reference they are connected to VIN.

The ref schem has pins 4 and 8 connected together to drive the motor, you only have pin 4 connected to the motor and don't have a pin 8 at all.

It is not possible to advise any further without a decent drawing, and there's no point at all in commenting on the PCB until the schematic is correct.

Hopefully making a better schematic is what you are doing now :)

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

TomGeorge

#20
Feb 01, 2014, 04:19 am Last Edit: Feb 01, 2014, 04:33 am by TomGeorge Reason: 1
Hi, can I make a suggestion, have a look at how other circuit diagrams are done, then go and look at yours.
You should be able to move any of the text, associated with any of the components, around to make clear non overlapping wires and text.
Also running wires through components is not done, it is confusing and in your case,place wires around outside of chips.
Your last attempt was a hundred percent better but still has some issues as Graynomad states.
What CAD did you use in the last schematic?


Tom........ :)
Everything runs on smoke, let the smoke out, it stops running....

Pedro147

Tom looks like one labelled original.png was done with Altium designer and schemati2.png with Eaglecad

http://www.pedroduino.com

graynomad

Yeah, original.png looks very Altiumish.

_____
Rob
Rob Gray aka the GRAYnomad www.robgray.com

MarkT


Tom looks like one labelled original.png was done with Altium designer and schemati2.png with Eaglecad




"Eagle" not "Eaglecad", if anyone wants to google it.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Pedro147


"Eagle" not "Eaglecad", if anyone wants to google it.


Yes Markt I usually just call it Eagle too but there is a lot who call it Eaglecad  :D judging by   
the Google search  you suggested
EAGLE (for: Easily Applicable Graphical Layout Editor CAD for Computer-aided design

Yeah but as we say over here"six of one, half a dozen of the other"
http://www.pedroduino.com

Jak24

Hi!

That schematic is just plain wrong, it does not match the reference at all as far as I can tell.

The "indecipherable" resistors on you schem are connected between the control signals, on the reference they are connected to VIN.

The ref schem has pins 4 and 8 connected together to drive the motor, you only have pin 4 connected to the motor and don't have a pin 8 at all.

It is not possible to advise any further without a decent drawing, and there's no point at all in commenting on the PCB until the schematic is correct.

Hopefully making a better schematic is what you are doing now :)

______
Rob

Attached the new schematic, hope its better, working on the board, I will put it up tomorrow.

Tom looks like one labelled original.png was done with Altium designer and schemati2.png with Eaglecad



Yes, but the Altium one, I didn't design, that Is the circuit for a pre-built motor controller I found on ebay, which I based my design on.

Hope the schematic is better, and hope you can advise what I should add/change.

Thanks

graynomad

Some pin names on the driver chips would be good.

And what regulator is it? I assume a switching reg as it has a diode and inductor on the output.

What's pin 6 on the reg?

Pin 5 on the reg has no overscore or other indication that it is active low so I assume active high, and yet it's tied low.

Half of the drivers have both .47u and 470u caps, the other half only have .47u. Is that correct? Are each pair sharing a large cap?

Component values typically have the units and are abbreviated. EG is that really a 470uF cap or 470nF? And 10000 is usually written as 10k. Thank goodness you didn't have any 10000000 10M resistors. :)

C11 and C8 don't have values.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Jak24


Some pin names on the driver chips would be good.

And what regulator is it? I assume a switching reg as it has a diode and inductor on the output.

What's pin 6 on the reg?

Pin 5 on the reg has no overscore or other indication that it is active low so I assume active high, and yet it's tied low.

Half of the drivers have both .47u and 470u caps, the other half only have .47u. Is that correct? Are each pair sharing a large cap?

Component values typically have the units and are abbreviated. EG is that really a 470uF cap or 470nF? And 10000 is usually written as 10k. Thank goodness you didn't have any 10000000 10M resistors. :)

C11 and C8 don't have values.

______
Rob

Attached the new schematic, sorry it took so  long, school got in the way :D
I think I addressed all the issues, hope it's ok!
I will post the -hopefully- final board design tomorrow,
Thanks for all your help!

cld_1

#28
Feb 07, 2014, 11:29 pm Last Edit: Feb 08, 2014, 12:30 am by cld_1 Reason: 1

I use 2 arduino's because I have 2 I2C devices and their address can't be changed for some reason... :P


Changing the subject a bit..

Surely there is simple way around that?  If the I2C devices don't have chip select pins, possibly a CD4053 or similar could be used to multiplex the I2C signals, or possibly there is an even simpler way?  

If it is only necessary to switch the clock signal SCL between the devices, a 'Fetlington' 2N7000 per device connected to a digital output pin would be rather simpler than a second Arduino...

Jak24



I use 2 arduino's because I have 2 I2C devices and their address can't be changed for some reason... :P


Changing the subject a bit..

Surely there is simple way around that?  If the I2C devices don't have chip select pins, possibly a CD4053 or similar could be used to multiplex the I2C signals, or possibly there is an even simpler way? 

If it is only necessary to switch the clock signal SCL between the devices, a 'Fetlington' 2N7000 per device connected to a digital output pin would be rather simpler than a second Arduino...

Again sorry for such a late reply.
Could you perhaps point me at a schematic/circuit for that.
However, wouldn't that cause a delay with the sensors response time?
And also I am think of using the extra analog pins on the mini as I need more than 16 analog inputs.

Any further advise/suggestions would be great!
Thanks


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