Aapen-term is a Pi Pico based dumb terminal. While the orignal motivation was to build a terminal to interact with the AApen operating system, Aapen-term is a more or less generic UART based dumb terminal.
Aapen-term consists of two main parts:
- There is board, based on the Raspberry Pi Pico 2040 which had connections for a UART, a VGA monitor and a PS2 keyboard.
- And there is the firmware that runs on the board.
Note that the VGA code is based on the original by Hunter Adams ([email protected]), which can be found on github.
- Make a build directory:
firmware/build. - Cd to the
builddirectory and runcmake ... - Either in the
builddirectory or infirmwareyou can now runmake.
At the end of the build you will have three different versions of the firmware:
firmware/build/term.uf2- This is the actual terminal firmware.firmware/build/test_ps2.uf2- This is a simple test firmware that will print a message for every keystroke.firmware/build/test_vga.uf2- This is a simple test firmware that print some text on the VGA screen.
The protocol implemented by the firmware is based on a simple stack oriented set of commands.
With the exception of the escape character, any byte received from the host is simply echoed out to the screen. The escape commands are:
- escape 1 - read the next byte and push it as a 16 bit number onto the stack
- escape 2 - read the next two bytes, turn them into a 16 bit number and push that onto the stack. Hi byte first.
- escape H - print hello on the screen
- escape P - pop the value off of the stack and print it on the screen
- escape l - toggle local echo
- escape D - drop a number from the stack
- escape r - pop color, h, w, y and x off of the stack and fill a rectangle.
- escape h - home the cursor
- escape p - pop x and y off of the stack and move the cursor to that character position.
- escape c - pop a number off of the stack and set the text color. Values 0-7.
- escape S - dump the stack onto the console
- escape X - reset the protocol handler
- escape T - display a VGA test screen.