Could some double check my layout?

Hey guys,

Just updating my Stripduino project to include a ftdi pins, and was wondering if someone could check this over with fresh eyes and see if iv dropped any clangers?


:slight_smile: thank you!!!!

How about a schematic of what you intend to have connected?

CrossRoads:
How about a schematic of what you intend to have connected?

ummmmm......Im now thinking a schematic could have been a good STARTING point!!!!

Basicly, going for a stand alone voltage regulated arduino, that will work with a 6 pin ftdi cable.

Issue: 328p’s pin1 connected to VCC (left hand side connector) ??
Issue: R2 - shall be 1k, for example…
Add:
I would add 100nF caps near chip’s VCC and GND (C6, C7)…
I would add 100nF cap from Aref to GND(C8)…

brd.bmp (179 KB)

Thanks pito!

Are caps C6,C7,C8 all smoothing caps?

Are caps C6,C7,C8 all smoothing caps?

Yes, they all are the decoupling caps…

Would they really be needed when using a DC power source like a 9v battery or regulated PS going through the LM7805 with decoupling caps?

(not disagreeing, just curious ^_^)

Would they really be needed

I would always recommend you to use it.. :wink:
PS: 100uF caps at the 7805 do not smooth higher frequency peaks.. You need something from 10nF-100nF to decouple higher frequencies or transients..

How about now?

And do I need to bother using D2 on the ftdi VCC pin, as iv seen a few other layout that just use a jumper?

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You have a short on the Vin and GND on the right side. Vin needs to be moved one pin down.

Iv got a cut in the track between the diode (d1) and the ground jumper over on the top right.....or am I missing another short?

You have a short on the Vcc and GND on the right side.

There is a drilled copper from bottom as I can see that…

But still the Vcc connector on the left side - you have to connect the Vcc with the Vcc somewhere…(but you miss a hole for it…) :slight_smile:
PS: or is it an INPUT from the USB serial dongle - to feed the board’s Vcc via the diode D2??

PS1: Frankly, I would go with 3V3 Vcc and I will use low drop voltage regler - so you can power it from a single lipo - lion cell fro example (328p works fine at 16MHz/3V3). Moreover, everything is 3V3 today, your life will be easier then…

n00b:
Iv got a cut in the track between the diode (d1) and the ground jumper over on the top right.....or am I missing another short?

Oh ok, I could barely see that.

pito:
But still the Vcc connector on the left side - you have to connect the Vcc with the Vcc somewhere…(but you miss a hole for it…) :slight_smile:
PS: or is it an INPUT from the USB serial dongle - to feed the board’s Vcc via the diode??

The plan was to use a 5v USB serial to ftdi cable that will feed the board through the diode…but if this is a bad idea i’m really option to suggestions!

pito:
PS1: Frankly, I would go with 3V3 Vcc and I will use low drop voltage regler - so you can power it from a single lipo - lion cell fro example (328p works fine at 16MHz/3V3). Moreover, everything is 3V3 today, your life will be easier then…

cool, lower power the better for me as I would like to use this in some sola powered applications!

(I could still use the 5v USB serial to ftdi cable too without any problem when running a 3v3 Vcc?

I am using following setup:
Vcc = 3V3 (see my latest post above)
Low dropout voltage regler - so you need 3.5V input to make the voltage regler happy
You can go then from USB dongle (Vcc on the left) via the D2 diode → to the INPUT of the voltage regulator… You need to switch off the VIN when using USB_VCC (or better, use a diode in VIN there as well, but that limits the lion-lipo battery range then)…
Use Schottky diodes (see below). Blocking capacitors not depicted…
If you plan low-power operation then do use an low-dropout regulator with ~uA quiescent current - ie MCP1700 or something like that. Also there are LEDs which lits fine at 150uA (when required there)…:slight_smile:

vreg.jpg

Got it, run both the Vcc and Vin though Schottky into the regulator on the top rail, and move the LED to another point on the board to free up that rail!?

See my comments above (I edited).
Do you need a power-on LED?? It consumes power.
I would suggest you to use the LED on the 328p's pin 19 (arduino standard = D13, or somewhere else) so you can blink, fade, and indicate the upload process with optiboot, for example..
Find a high-brightness LED and use a larger resistor (ie 4k7). Mind the LED is connected via R2 to GND !!
You can also switch the LED off then - a nice feature, indeed.. :slight_smile:

I'd like to have the option of a power LED, and a Dig pin 13 one too for that matter, even if I chose not to use them XD

But a couple of diode questions:

1: If I was to go with the 5v version as it is on the previous posted layout (using 5v Vcc for the USB ftdi) what value diodes should I use
2: if I use both Vcc and Vin into 3v3 regulator, what voltage Schottky diodes should I use?

Just can't bring yourself to do a schematic, eh?

CrossRoads:
Just can't bring yourself to do a schematic, eh?

I think at this point installing Eagle cad, getting appropriate libraries and laying out the schematics is going to take a fair bit of time I just don't have spare, and I don't think the circuit i'm talking about here is either complicated enough or unfamiliar to a extent that require a schematic to solve the problem of the two remaining questions about diode values.

Sure starting with a schematic is good practice, and I will try and follow that in the future.....but it seems a little pointless to do one now?