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Topic: 1284p/nRF24L01+/proto dev board - Skinny Bob! :-) (Read 36971 times) previous topic - next topic

bluesmoke328


What is your application, if you don't mind me asking?


Robot(s). Need. Ram.

With 16K and lots of prototyping/expansion options this looks "da bomb". Not just in my usual way of blowing things up I hope. Although I expect that too. A socketed chip is nice to have there.

pico

#16
May 24, 2014, 04:53 pm Last Edit: May 27, 2014, 04:06 pm by pico Reason: 1
"Skinny Bob" now available:

http://embeddedcoolness.com/shop/rfx-1284p-devdep-board-w-prototyping-area-nrf24l01-headers-kit/

(Also created new thread in "Products and Services" section.)
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OldMicroGuy

Skinny Bob looks cool.   
Are you going to post a schematic?

Roger


pico


Skinny Bob looks cool.   
Are you going to post a schematic?


Yes, when I put together a "pretty" one, rather than the actual one used in Eagle development! Drawing proper connections and laying the components out nicely rather than connecting everything up by "name". You know, "nice". ;-)

If there's anything particular in the meantime you are curious about, let me know.

WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

CrossRoads

I'd rather see by name - so much easier to follow than little green lines all over the place.
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.

pico

#20
May 29, 2014, 04:48 am Last Edit: May 29, 2014, 04:52 am by pico Reason: 1

I'd rather see by name - so much easier to follow than little green lines all over the place.


Yes, I agree, much better during development. Unfortunately, what you end up with isn't what most people are thinking of when they ask "can I see the schematic?"

What would be sweet is if Eagle had a function to produce a "prettified" schematic automatically. laying out the components and drawing in all the nets as wires -- I was thinking about this, and realised that it's actually basically an auto-routing problem with a different output format.

But given the results I typically get from the standard Eagle auto-router, maybe this isn't such a good idea!
WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

bluesmoke328


If there's anything particular in the meantime you are curious about, let me know.


Could you explain in more detail exactly how the power configuration options you mention in the first post in this thread works?

pico

#22
May 31, 2014, 04:37 pm Last Edit: Jun 01, 2014, 05:26 am by pico Reason: 1

Could you explain in more detail exactly how the power configuration options you mention in the first post in this thread works?

LOL, yes, that description of the power rail configuration options in the first post is a bit "stream of consciousness" - sorry about that. I think I must have written that a bit too close to the time I had my head down in the nitty gritty of the board design.

In reality, the options are pretty simple. 99% of the time it boils down to whether you want to run Vcc to the chip at 5V or 3v3. In that case, there are two jumper settings to choose from.

So, let's assume you are primarily powering the "Skinny Bob" board from a DC supply >= 6V applied to Vin, either by the barrel jack or to the Vin rail directly (e.g., via a header pin).

On the 2x3 male pin power header, the jumper setting for 5V looks like this:

  o  o  o
[o  o] o
5V Vcc 3v3

And 3v3 looks like this:

  o  o  o
  o [o  o]
5V Vcc 3v3

That's it. Move one jumper to choose 5V or 3v3 Vcc for the 1284p.

So what are the jumper pins on the top row used for?

These are for less usual situations when you want tie rails together for some reason, typically for when you would be using some other arrangement for power than 6V+ supplied to Vin. (I'll elaborate a bit further in a follow-up post on some more "exotic" possible configurations, perhaps when I've drawn up a nice schematic.of the power section.)

And finally, what about switching to a USB power input from the Vin power input? E.g., what if we want to power the board by connecting a USB/TLL cable to the USB/TTL header, or an ISP programmer to the ICSP header? Do we have to change the power jumper block settings in that case?

Well, no. Just like a standard Arduino, the "Skinny Bob" will automatically switch to using a power supply available from USB on the 5V rail if there is no supply on Vin. It achieves this via a considerably simpler "auto-switching" mechanism (using a Schottky diode) than the FET/op-amp arrangement on the Arduinos, but ultimately the same effect.

So all pretty uncontroversial and unexciting so far. Which is as planned. As I say, I'll get back with a description of some more special case possible power configurations.

WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

pico

#23
Jun 03, 2014, 06:15 pm Last Edit: Aug 05, 2014, 05:16 pm by pico Reason: 1
Ok, so back with a schematic! :-)

So, when might you use the top row of pins on the power configuration header to tie rails together?

On the 2x3 male pin power header, the second jumper setting on the top row for tying the 5V rail to Vin looks like this:

5V Vin 3v3
[o  o] o
[o  o] o
5V Vcc 3v3

You might want to do this if you were supplying a regulated 5V through the barrel jack connector, instead of the usual 6V+ supply.

In that case, tying the 5V rail to Vin would bring the 5V rail up to the full 5V level. Otherwise, it would be less than 5V, as there would be a voltage drop from 5V on the rail due to the LD1117v50 regulator.

Also note that in this case, you could dispense with installing the onboard 5V regulator entirely, if you wanted to. Note the 3v3 rail would still be supplied as normal by the LD1117v33 regulator, assuming that's installed. So you would still have the choice of running Vcc at 5V, as above, or at 3v3, as below:

5V Vin 3v3
[o  o]  o
 o  [o  o]
5V Vcc 3v3

Analogously, you could tie the 3v3 rail to Vin directly if you were supplying regulated 3v3 via Vin. In that case, you could dispense with both onboard regulators, if so desired. (Of course, 5V wouldn't be an option for Vcc unless there was some other source feeding the 5V rail.)

5V Vin 3v3
 o  [o  o]
 o  [o  o]
5V Vcc 3v3

So there are a couple of the more specialized power configuration options available. Anyway, the design philosophy is that flexibility is a good thing, as long it doesn't lead to confusion or makes it too easy to shoot yourself in the foot. Hopefully this design provides a good balance.

WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

OldMicroGuy

Hi pico,

That .jpg of the schematic is a bit hard to read.  Any chance of posting a hi-res .pdf?
Roger

pico


Hi pico,

That .jpg of the schematic is a bit hard to read.  Any chance of posting a hi-res .pdf?
Roger



Done.
WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

retrolefty

Only suggestion I might make is to power the 3.3 vdc regulator from the output of the 5 vdc regulator rather then feeding the 3.3vdc regulator from the Vin source voltage. That way if one was to power the board via an external regulated 5 vdc the 3.3vdc would be available?

pico

#27
Aug 05, 2014, 06:39 pm Last Edit: Aug 05, 2014, 07:01 pm by pico Reason: 1

Only suggestion I might make is to power the 3.3 vdc regulator from the output of the 5 vdc regulator rather then feeding the 3.3vdc regulator from the Vin source voltage. That way if one was to power the board via an external regulated 5 vdc the 3.3vdc would be available?



It's actually got an auto-power switching circuit using a Schottky that will power the 3v3 VR from the 5V rail, unless there is a higher voltage on the Vin input, in which case it will draw power from that.

So, just like a standard Arduino board you can power it from the USB 5V (which is tied to the 5V rail), or the Vin, without having to set a connector to select the power source. The switching is just done all a bit more straightforwardly than the fairly Byzantine op-amp/FET set-up on an Arduino Uno, for example.  :smiley-mr-green:

And this way, with an adequate supply on Vin, you get two full 800mA rails, at 5V and 3v3, (as opposed to 800mA combined total for both rails.)

Also, if you chose to supply a regulated 5V on Vin, the Vin and 5V rail can be directly tied together by a jumper on the power jumper block. In that case you could actually dispense with the 5V regulator entirely if you wished. And the capacity of the 5V rail would then only be limited to whatever your external supply can provide. Quite a neat solution for higher power applications, as long as you have a reasonable quality regulated external 5V power supply.

So short answer is yes, applying 5 vdc to the 5V rail directly will also result in power to the 3v3 rail with the current design.
WiFi shields/Yun too expensive? Embeddedcoolness.com is now selling the RFXduino nRF24L01+ <-> TCP/IP Linux gateway: Simpler, more affordable, and even more powerful wireless Internet connectivity for *all* your Arduino projects! (nRF24L01+ shield and dev board kits available too.)

retrolefty

Quote
It's actually got an auto-power switching circuit using a Schottky that will power the 3v3 VR from the 5V rail, unless there is a higher voltage on the Vin input, in which case it will draw power from that.


Ah, missed that feature of the added diode, thought it was just to protect the 5 vdc regulator, cleaver.

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