qmk_firmware/keyboards/1k/rules.mk

# MCU name
MCU = attiny85

# Bootloader selection
BOOTLOADER = custom
BOOTLOADER_SIZE = 1862
PROGRAM_CMD = micronucleus --run $(BUILD_DIR)/$(TARGET).hex

# Build Options
#   change yes to no to disable
#
BOOTMAGIC_ENABLE = no       # Enable Bootmagic Lite
MOUSEKEY_ENABLE = no        # Mouse keys
EXTRAKEY_ENABLE = no        # Audio control and System control
CONSOLE_ENABLE = no         # Console for debug
COMMAND_ENABLE = no         # Commands for debug and configuration
NKRO_ENABLE = no            # Enable N-Key Rollover
BACKLIGHT_ENABLE = no       # Enable keyboard backlight functionality
RGBLIGHT_ENABLE = no        # Enable keyboard RGB underglow
AUDIO_ENABLE = no           # Audio output

# Save as much space as we can...
LTO_ENABLE = yes
GRAVE_ESC_ENABLE = no
MAGIC_ENABLE = no
SPACE_CADET_ENABLE = no