Blink

03_reset_resistor

10 kiloOhm ‘pull-up’ resistor

Look for a brown or blue cylinder with a wire at each end, with stripes of Brown, Black and Orange. Resistors have no orientation, so you can’t wire them backwards.

This will be used as a pull-up resistor. A positive voltage, usually 5V, ‘pulls up’ the reboot pin (Pin 1) through this resistor. The ATMEGA will keep running so long as it gets a high voltage on this pin. When reprogramming, the brown wire is briefly connected directly to 0V, (a stronger signal than the flow from 5V limited by the resistor). Pin 1 therefore gets pulled to 0V which causes the chip to reboot. After rebooting the ATMEGA listens for a new program sent over the orange wire. If nothing is sent, it runs the last program.

The colored stripes are decoded just like the ‘104’ capacitor earlier, but colors are used instead of digits. Decoding the colors Brown=1, Black=0, Orange=3 gives us the number 103. That means the resistance in Ohms starts ‘10’ and continues with a further 3 zeroes – 10,000 Ohms or 10 kiloOhms.

Attach the resistor with Brown, Black and Orange stripes between…

  • row 9 on the breadboard (will be the positive power line, approx. 5 Volts)
  • the top left leg of the chip (pin 1, immediately anticlockwise from the half-moon shape)

19 Responses

  1. Colton
    Colton October 23, 2013 at 1:22 am | | Reply

    This device is so awesome it solved all of my problems of finding an affordable development board and I plan on making one. I found this site on Hack-A-Day!

  2. gjs
    gjs November 10, 2013 at 12:04 pm | | Reply

    does the crystal not need any power?

  3. Walt
    Walt November 10, 2013 at 6:23 pm | | Reply

    What should the “Arduino Programmer” be set to? I see options: AVR ISP, AVRISP mkII, USBtinyISP, USBasp, Parallel Programmer & Arduino as ISP.

  4. femi
    femi November 24, 2013 at 9:16 pm | | Reply

    avrdude: stk500_getsync(): not in sync: resp=0x00

    I keep getting the above error at step 12 any tips?

    1. efficacy
      efficacy January 20, 2014 at 1:52 pm | | Reply

      I got this, and checked my circuit several times, but everything seemed OK. Then I checked the AVR chip itself. I had bought my own components and inadvertently ordered a chip without a “bootloader”, so the Arduino IDE did not recognize it as a Uno.

      If this is your problem, then its easy enough (although often a bit more costly) to get the chip pre-programmed with the bootloader, or you can go the hacker route and build your own ISP (bootloader programmer). I followed the instructions at http://learn.adafruit.com/arduino-tips-tricks-and-techniques/arduinoisp and can now buy the cheaper, unprogrammed AVR chips in bulk and put whatever bootloader I like,

  5. Blink | Physical Computing | Scoop.it
    Blink | Physical Computing | Scoop.it December 16, 2013 at 3:48 pm |

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  7. Martin
    Martin May 10, 2014 at 4:33 pm | | Reply

    I have got to step 12 of blink and haven’t managed to get it blinking. I’m fairly certain everything is wired correctly and all the components are in the right place.

    I have downloaded the CP2102 installers for windows 8 from your website.

    When I tried to upload the blink programme from Arduino it says ‘Serial port “com 1″ not found.’ I checked the serial port in ‘tools’ but it was greyed out and I can’t select it.

    I may be wrong but I think that somehow I haven’t installed the drivers properly. I checked the USB in my PCs device manager and tried to update the device driver, but when I browsed for it in my computer it says it can’t find the driver software.

    Do you have any suggestions about what I’m doing wrong?

  8. onewolfmusic
    onewolfmusic June 25, 2014 at 11:24 am | | Reply

    Hi there, just got my USB to serial through, but it doesn’t have a DTR pin. It does however have an RST, being a total noob I thought I’d ask – have a bought the wrong adapter, or will this one work?

    Thanks

    Ross

  9. marl
    marl August 1, 2014 at 6:23 am | | Reply

    So, what do I do if I didn’t buy a pre- bootloaded atmega 328p?

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