If you wish you update LEDI with the latest firmware, you’ve come to the right place. To take advantage of the latest LEDI development, it is advisable that you acquire the tools and the know-how to flash LEDI’s firmware.

You will need 3 things in order to upgrade the firmware on your LEDI.

What You Need What It Is
1 latest firmware file with extension .hex
2 ISP (In-System Programmer) "burns" the .hex file onto the chip
3 avrdude sends the firmware file to ISP for upload

Disclaimer: We are not affiliated with any of the companies that make any of the programmers mentioned in this tutorial.


The main clock source of LEDI is the internal RC oscillator. By default, the Atmega328p chips come with 2MHz max frequency on the internal clock. However, we need to overclock this. LEDI runs at 8MHz and in order to run at this higher frequency, you need to modify the fuses.

In order to modify our chip to run at 8MHz, run this on your terminal. You will need avrdude to do this:

avrdude -F -p m328p -P usb -c avrispmkII -U lfuse:w:0xE2:m

Obtaining the Firmware

The latest firmware source code is in git repository:


The latest firmware will be placed under


You can also easily pull the entire project from git:

git clone https://github.com/techversat/ledi_firmware.git
# or
git clone git@github.com:techversat/ledi_firmware.git

If you are new to git, we suggest reading this page first: https://help.github.com/articles/set-up-git

Choosing the Programmer

Atmel’s microcontrollers are quite popular with the hobbyist community. As such, there are variety of hardware choices available. We’ve listed some of the programmers we’ve personally tested.


Programmer Synopsis Comments
avrisp mkII you like brands Official programmer by Atmel. Can’t go wrong, but pricey in comparison
avrisp clone personal fav Cheap, yet reliable. Powers the target
littlewire multi-purpose Relatively cheap, can be used for other purposes besides programming.
USBTiny easy to follow Great resources online from adafruit.com

No matter which programmer device you choose, you will use a single software to communicate against it: avrdude

Setting up the FlashingSoftwre

avrdude is a command line utility which works for Windows, Mac OS X, and Linux. It can flash most Atmel produced microcontrollers, and also can modify configuration "fuses" on these chips.

For Linux

Simply run:

sudo apt-get install avrdude
which avrdude

You then need to give proper system permissions for ISP device. Create a file called /etc/udev/rules.d/99-avrisp.rules with this content:

SUBSYSTEM=="usb", SYSFS{idVendor}=="1781", SYSFS{idProduct}=="0c9f", GROUP="plugdev", MODE="0666"

The run:

sudo service udev restart

For more detailed instructions, please refer to:

http://www.ladyada.net/make/usbtinyisp/avrdude.html http://www.ladyada.net/learn/avr/setup-unix.html

For Mac OS X

There is an excellent all-in-one package called CrossPack-AVR on OS X.


This package is one-stop-shop. It gives the development environment as well as the avrdude. Very neat.

Connect Programmer to LEDI

On the bottom right side of LEDI (next to the microcontroller), you will see 2×3 header. That’s where the ISP connector goes. The top right pin is annotated with a small triangle. That’s where the red strip on the ribbon cable will align:

| o   o   o | <- first pin (MISO)
| o   o   o |

Here’s how the ribbon cable is connected to the LEDI board:


Notice the small triangle engraving on the ribbon cable adaptor. The triangle points to the first pin, the same pin where the red strip corresponds to.


Flash with New Firmware

Once you have the programmer connected to the LEDI board, and the programmer is connected to the USB port on your PC, you are ready to flash the firmware.

If you have downloaded the ledi_firmware repository, you can also simply do:

cd ledi_firmware/src
make upload
# or if you have tinyisp, littlewire
make tinyisp

If you only downloaded the firmware file, run the following commands for the programmer you own. It assumes your firmware file is named main.hex and exists in current working directory.

avrisp mkII or avrisp clone:

avrdude -V -F -P usb -c avrispmkII -p m328p -U flash:w:main.hex

littlewire or usbtiny:

avrdude -V -F -c usbtiny -p m328p -U flash:w:main.hex


  • If you have Atmel’s avrispmkII, make sure you power LEDI with the DC adaptor. The programmer does not supply power to the board, and the board will simply be off if you only had avrispmkII plugged in.

  • To confirm whether your PC sees the programmer, you can try the following command on linux. It should show a device with USB signature 03eb:

    $ lsusb | grep -i atmel
    Bus 002 Device 011: ID 03eb:2104 Atmel Corp. AVR ISP mkII
  • Make sure you have the correct connection of the programmer to the LEDI board. Verify the pinouts of your programmer and match the pinouts on the LEDI board:

    LEDI ISP Connection
      R   C   I
      S   L   S
      T   K   O
    | o   o   o | <- first pin (MISO)
    | o   o   o |
      G   M   V+
      N   O
      D   S