ESP32-P4 Feather board
This is an open-source Feather-format board that you can build yourself. It's based on the Espressif ESP32-P4 high performance RISC-V processor, and it runs uLisp:
The ESP32-P4 is a dual-core RISC-V processor running at up to 400MHz, with 768KB of on-chip SRAM, 32Mbytes of on-chip PSRAM, and up to 32Mbytes of external flash. The board can be powered through the USB port, or from a LiPo battery with charging through the USB port.
For full details see ESP32-P4 Feather Board on Technoblogy.
Example
As an example of using the ESP32-P4 Feather board, here's a variant of the simple Blink program in Lisp.
The ESP32-P4 Feather board has a red LED connected to pin 1. You can flash "SOS" in morse code with the following program:
(defun blink-sos ()
(let ((message #*1010100011101110111000101010000000))
(pinmode 1 :output)
(loop
(dotimes (i (length message))
(digitalwrite 1 (aref message i))
(delay 250)))))
This uses a Lisp bit array to specify the sequence of dots and dashes. Run it by typing:
(blink-sos)
Exit from the program by entering ~ followed by return.
You can save the blink program to flash memory by typing the command:
(save-image)
You can now load it again after a reset by typing:
(load-image)