- Apple II archaeology - Apple II archaeology is a collection of Lisp code useful for Apple II retrocomputing
- Arduino Lisp - Arduino Lisp is a compiler from a subset of Common Lisp to the subset of C++ used by the Arduino C++ compiler
- arduino-experiments - arduino-experiments is a library for interfacing to the Arduino embedded computer via serial I/O from Lisp
- cl-larval - S-Exp syntax to write assembler for AVR microcontrollers
- cluck - Cluck is a Common Lisp library written by Kevin Rosenberg for assisting in configuring timers on microcontroller chips
- common-db - common-db is a programmable debugging substrate, mostly geared to driving target devices by establishing control via on-chip debugging machinery through a JTAG (IEEE 1149.1) external port
- uLisp - uLisp is an embedded Lisp for microcontrollers, supporting Arduino, Adafruit M0/M4, Micro:bit, ESP8266/32, and RISC-V boards
Code for dealing with embedded systems. You also might want to check system programming.