ATmega4809 Curiosity Nano

Microchip's ATmega4809 Curiosity Nano evaluation board makes a very low-cost platform for running uLisp.

The ATmega4809 provides 48 Kbytes of flash memory, 6 Kbytes of RAM, and 256 bytes of EEPROM, and runs with a 20MHz internal oscillator. The board includes a debugger, providing a USB-to-serial interface:


It's available from suppliers such as Farnell [1].

Installing uLisp from the Arduino IDE

  • First download the latest AVR version of uLisp from the Download uLisp page.
  • Install MCUdude's MegaCoreX from GitHub, as described in MegaCoreX - How to install.
  • On the Board menu, under the heading MegaCoreX select Atmega4809.
  • Check that the subsequent options are set as follows (ignore any other options):

Clock: "20MHz"
Pinout: "48 pin standard"
Programmer: "Atmel nEDBG (ATSAMD21E18)"

  • Connect the board to the computer via USB.
  • Select the device corresponding to the USB port from the Port menu.
  • Upload uLisp to the board.

You should then be able to select Serial Monitor from the Tools menu, and enter Lisp commands.


The Curiosity Nano has a yellow LED connected to pin 39 which you can flash with the following program:

(defun bli (&optional x)
  (pinmode 39 t)
  (digitalwrite 39 x)
  (delay 1000)
  (bli (not x)))

Run it by typing:


Exit from the program by entering ~.

Pin 39 can also be used as an analogue output pin, so you can pulsate the yellow LED slowly on and off with this Pulse program:

(defun pls ()
   (dotimes (x 512) 
     (delay 5) 
     (analogwrite 39 (if (> x 255) (- 511 x) x)))))

Run it by typing:


As before, exit from the program by entering ~.

You can save the Pulse program to EEPROM by typing the command:


You can now load it again after a reset by typing:


Note that there's very little EEPROM on the ATmega4809, so this is close to the largest program you will be able to save with (save-image).

  1. ^ DM320115 - Evaluation Board, Curiosity Nano, ATmega4809 on Farnell.