Cathy3K

An assembly optimized bootloader in 3K for Arduboy based on reversed Caterina bootloader.

Main features

Bootloader size is under 3K alllowing 1K more space for Applications
Built in menu to select and burn programs from external serial flash memory
100% compatible with Arduino IDE uploading
No bootloader time out
Power on + Button Down launces bootloader instead of programmed sketch
A USB icon is displayed in bootloader mode when there is no serial flash chip or has not been initialized.
Identifies itself as serial programmer 'ARDUBOY'
Added command to write to OLED display
Added command to read button states
Added command to control LEDs and button input
Added command to read and write to serial flash memory
Sketch self flashing support through vector at 0x7FFC
Software bootloader area protection to protect from accidental overwrites
closing com port @ 1200 baud while in bootloader mode will restart bootloader (speeds up Arduino IDE uploading while in bootloader mode)

the following obselete commands where removed:

Flash Low byte, flash high byte and Page write commands are removed. These commands are not used because flash writing is done using the write block command.
Read flash word command. Again it is not used because all flash reading is done using the read block command. A single word can be read as a 2 byte block if required.
Write single EEPROM byte. Command not used. write EEPROM block command is used instead. A single EEPROM byte can be written as a one byte block.
Read single EEPROM byte. Command not used. read EEPROM block command is used instead. A single EEPROM byte can be read as a ne byte block.

Flashing bootloader

The easiest way to flash the bootloader is through the Arduino Arduboy IDE with the Homemade package installed. When flahing manually using AVRdude you'll also need to flash the fuses BOOTSZ1 = 0 BOOTSZ0 = 1 (2K-byte/1K-word).

Recommended fuse settings: LFUSE:0xFF EFUSE:0xCB HFUSE:0xD2

building bootloader

To (re)build the bootloaders. Install the Arduino IDE and run the make3k-all.sh script.

bootloader filenames

The batch file creates many bootloaders for Arduboy and many homemade Arduboy configurations, keywords in the filename help indentify a specific target. Without keywords the bootloader is for Arduboy/Leonardo/ProMicro standard wiring with SSD1306/SSD1309 display and Rx as flash chip select.

game

After powering on the last flashed game is run immediately. Pressing down while switching on or pressing reset will enter the bootloader menu.

Micro

Bootloader for the Arduino Micro which has The Rx and Tx LEDs polarity reversed.

ProMicro

Bootloader for ProMicro using alternative wiring.

devkit

Bootloader for original Arduboy DevKit

sda

The SDA pin is used to select the serial flash chip instead of the Rx pin.

sh1106

Bootloader for using a SH1106 OLED display

ssd132x 96x96 128x96 128x128

Bootloader for using a SSD1327/SSD1329 OLED display with pixel resolutions 96x96, 128x96 or 128x128

st7565

Bootloader for using a st7565 LCD display with backlight

menehune23/cathy3k-dotmg