The standard Nano you have is using the Duemilanove bootloader, which works at 57600. Even though it's a different form factor, you program it by picking "Duemilanove" from the board type menu.

The Uno uses OptiBoot for its bootloader, which works at 115200 baud. It's the new standard because it's smaller (512 bytes vs about 2K). When you burned your new standalone chip you got OptiBoot.

So, if you treat your new Nano clone as a Uno, everything should work fine.

Good luck!

im always getting a value (with no pins connected what so ever, only usb cable!), and the longer my uno is on with that code, the more the value increases.
How come ?

Noise. You don't have the pin connected to anything, so it's picking up noise.

On Nick Gammon's page see the section "how to get a response from a slave". Specifically the code line

Code:

byte a = SPI.transfer (what);

On the master you call SPI.transfer() to send a byte to the slave, and the function returns the byte coming from the slave.

How do you burn a new bootloader to a chip on a surface mount board such as Nano?

The exact same way. D10 on the Arduino running the bootloader upload script to the reset pin on the Nano, D11 - 13 from the uploader to pins D11 - 13 on the Nano, ground to ground, and 5v to 5v.

RP is correct, the default Nano bootloader is the one from the Duemilanove.

I reflashed my Nano with OptiBoot (the bootloader used on the Uno) and have had no problems. I've now got OptiBoot running on all my boards & standalone chips; now I can leave the board at "Uno" and not have to switch every time I move between projects.

Correct. Stepper motors are current driven. It's very common to drive stepper motors at 12-30 volts when using stepper controllers like the A4988 (used on the Big Easy Driver).

Good luck!

Does the Avaya phone speak Ethernet like a regular client (so it will be on whatever VLAN the switch port defaults to), or does it speak VTP (so it can negotiate which VLAN it will use)?

For the former, you can probably just use plain old DHCP with at most hardcoding a MAC address similar to a phone.

For the latter, I don't know of any Arduino libraries that can use the VLAN trunk protocol so you might have to roll your own. One thing you could do is sniff the packets between a real phone and the switch, then mimic them with your Arduino.

Good luck!

Nick Gammon has an excellent writeup on SPI, including master/slave data exchange, at:

http://www.gammon.com.au/forum/?id=10892

Good luck!

So why is there also sda/scl pins in R3?

The ATMega328 used on the Uno uses A4 & A5 for I2C, so for the Uno they're the same pins.

On the Leonardo, however, the ATMega32U4 uses pins D2 and D3 for I2C. The Due also uses something other than A4/A5.

If a shield needs I2C connectivity and uses A4/A5 it will only work with a Uno (and the older 328/168 boards). If a shield uses the SCL/SDA pins, however, it should work with all the Arduinos (except the old ones, which don't have those pins)

I should look over digikey and mouser more often, but I find them those sites a bit overwhelming.

I agree they can be daunting at first but they're manageable. I much prefer DigiKey's interface; I find it the easiest to use. Many times if I get something from Mouser, Newark, etc. I'll find it on DigiKey then cut & paste the part # at the other sites.

I start by searching for as close to what I need as possible, e.g. "atmega328p-au" or "1/4 watt 10k resistor". This generally does a good job of getting close.

Next I check the "In Stock", "Lead Free", and "RoHS Compliant" boxes and search again; there's usually no point in searching if they don't have it in stock and the other two seem to help whittle things down further.

Next I start going through the search boxes like "packaging" or "height", etc. for things I know I want, e.g. a specific size or footprint and click "apply filters" each time.

When the result list is a reasonable size I sort by "unit price" and buy the cheapest one (unless I know I'll eventually need a lot of the part, in which case I give "quantity available" some weight).

Having said all that, I try to do as CrossRoads says and batch up purchases at one of the Chinese companies; this is usually the overall least expensive option.

Your question is a little vague...what do you want to do with them?

There's the SPI library, you can use that to send data to shift registers faster than shiftOut().

There's the ShiftPWM library (http://www.elcojacobs.com/shiftpwm/) if you want to blink some LEDs...

Where do you get resistors for less than one cent each? I get them cheap on the internet, and they are 2-5 cents each, in packs of 100 or more.

Pretty much anywhere. Here's some 10K resistors from DigiKey for 0.2 cents each at qty 100:

http://www.digikey.com/product-detail/en/1622826-4/A106045CT-ND/3477682

As an aside, this is easily my favorite thread of the new year.

So running the LED for half the time only loses a quarter of the perceived brightness,  and you could go down to 1:7 ratio before losing half the perceived brightness.

That makes sense, your eyes perceive light intensity as a logarithmic function. Here's the short table I use:

Step | Duty
===========
  0  | 0
  1  | 1
  2  | 3
  3  | 7
  4  | 15
  5  | 31
  6  | 63
  7  | 127
  8  | 255

Hello I have bought 4 8*8 LED Matrix.

And I saw this circuit and I have built it (eventually have all the components).
Do anybody here know how to program the LED Matrix?
Is there any available library for LED Matrix and those shift registers?

Thank you.
 

Hi,

For clarification -- do you want help to program the 8*32 matrix that you built exactly like the schematic you attached (including the At90s2313), or do you want to build an 8*32 matrix similar to the schematic but controlled by an Arduino?

For the former, it looks like you'd use the SPI bus to communicate between the Arduino's ATMega and your circuit's At90s2313, but you'd have to look at the At90s2313's programming to see how you communicate with it.

For the latter, the easiest way I know to do what you want is to replace the 74hc259 with another 74hc595 (outputs driving the ULN2003, inputs on the same bus as the rest of the 74hc595s) and use the ShiftMatrixPWM library.

Good luck!

This is why large commercial displays do not utilize multiplexing

I was under the impression that all large displays, commercial or otherwise, use multiplexing like this one:

https://www.adafruit.com/products/607

Using one driver per pixel seems like it would cost infinity money.