Stub project for "new" 0-series megaAVR microcontrollers

This is a sample project demonstrating how to compile and upload code for the new ATmega808/809/1608/1609/3208/3209/4808/4809 microcontrollers without using an IDE.

These new chips do not use the 2x3-pin ISP connection for flashing. Instead, they use a 1-wire protocol called UPDI. You won't need a special programming device, just an FTDI USB-to-serial cable.

Note: these instructions are currently only for macOS and Linux.

Installing the toolchain

If you've done AVR development for the previous-generation Atmel chips (ATmega328P, ATmega644P, ATtiny85, etc.) you've probably installed the GNU distribution of avr-gcc/avr-libc from your OS's package manager (Homebrew, apt-get, etc.) However (as of 1/7/2020) support for these newer parts is only available in Microchip's toolchain. Installing it is a somewhat manual process, but is fairly straightforward.

1. Download the AVR 8-bit toolchain for your platform from Microchip's site. You'll wind up with a file named something like avr8-gnu-toolchain-osx-3.6.2.503-darwin.any.x86_64.tar.gz or avr8-gnu-toolchain-3.6.2.1759-linux.any.x86_64.tar.gz.
2. Extract this archive. You'll wind up with a directory named something like avr8-gnu-toolchain-darwin_x86_64 or avr8-gnu-toolchain-linux_x86_64.
3. Move this directory to a system-wide location, like /usr/local or /opt/local. (The Makefile in this repo assumes you are using /usr/local.) Use sudo if necessary.
4. Download the "Atmel ATmega Series Device Support" package from http://packs.download.atmel.com.
5. Change the file extension on the downloaded .atpack file to .zip and unzip it. You'll wind up with a directory named something like Atmel.ATmega_DFP.1.4.346.
6. Move this directory to the same directory from step 3. Use sudo if necessary.
7. Download pyupdi from GitHub: https://github.com/mraardvark/pyupdi/archive/master.zip.
8. Unzip the archive and rename the directory from pyupdi-master to pyupdi.
9. Move the pyupdi directory to the same directory as in step 3. Your base directory (e.g. /usr/local) should now contain these three subdirectories:

• avr8-gnu-toolchain-<osname>/
• Atmel.ATmega_DFP.<version>/
• pyupdi/

10. If you don't have the PySerial and IntelHex packages installed, install them with pip3 install pyserial intelhex.

Building

If you installed the tools in a directory other than /usr/local, change the value of AVR_BASE_DIR in the Makefile appropriately.

Run make to build the hex file.

Uploading

Connect your FTDI cable to the chip and power it up. If this is a brand new chip, run make fuse to configure the fuse bits for a 20MHz clock frequency.

Run make flash to upload your code! The example program (blink.hex) will blink an LED connected to PD7 (pin 27 on TQFP parts, pin 16 on PDIP parts) once per second.

UPDI circuit

All you need is an FTDI cable and a 4.7k resistor. For TQFP/QFN chips, the UPDI pin is pin 41. For DIPs, it's pin 30.

  ┌───┐                    ┌──────────┐
  │BLK├───GND              │          │
  │BRN│─x                  │          │
  │RED│─x                  │          │
  │ORN├────[4.7kΩ]──●──────│UPDI      │
  │YEL├─────────────┘      │          │
  │GRN│-x                  │          │
  └───┘                    └──────────┘
FTDI cable                  ATmega4809 

License

The contents of this repository are released to the public domain.