libflipdot

Flip Dot Display driver for Raspberry Pi
https://wiki.attraktor.org/FlipdotDisplay

Uses

• Everything that can be converted to a bitmap
• Flip Dot Camera
• Flip Dot Spectrum Analyzer
• Clock
• Video Wall with vlc

Installation

• Install the bcm2835 library
• Edit flipdot.h
  • configure GPIO to display input mapping
  • configure display geometry
• Connect display to GPIOs
• make
• sudo ./examples/fliptest
• sudo ./examples/flipclear
• echo 'Hello World!' |toilet -f 3x5 |sudo ./examples/flip_pipe

Beware of signals!
Terminating a program while one of the OE outputs is still set will keep the display transistors on and may cause damage to the matrix or the driver board. Call flipdot_shutdown() or run sudo ./examples/flipoff to turn the GPIO outputs off.

Examples

flip_pipe: Reads an ASCII bitmap followed by an empty line (\n\n) from stdin and sends it to the display, loops until EOF. Use this 3x5 figlet font to pipe text onto the display.

flipspect_record: Flipdot Spectrum Analyzer. Samples audio from ALSA input and displays the FFT output. Requires FFTW3 and ALSA.

To use the library for your own code, copy flipdot.h and libflipdot.a where compiler and linker will find it. Link with -lflipdot

Functions

void flipdot_init(void);
Initialize hardware and internal buffers

void flipdot_shutdown(void);
Shut down hardware outputs

void flipdot_clear(void);
void flipdot_clear_to_0(void);
Flip all pixels to position 0

void flipdot_clear_to_1(void);
Flip all pixels to position 1

void flipdot_clear_full(void)
Flip all pixels to 0, to 1 and back to 0. This should recover pixels stuck in the middle between end positions

void flipdot_display_row(const uint8_t *rows, const uint8_t *cols);
Flip all pixels in rows selected by rows to positions set in cols.
The internal frame buffer is not updated to reflect the changes

void flipdot_display_row_diff(const uint8_t *rows, const uint8_t *cols_to_0, const uint8_t *cols_to_1);
Flip 0-bits in cols_to_0 and 1-bits in cols_to_1 in rows selected by rows.
The internal frame buffer is not updated to reflect the changes

void flipdot_display_frame(const uint8_t *frame);
Display a full display frame.
frame contains all pixels shifted into the display registers, including blind gaps between horizontal modules

void flipdot_display_bitmap(const uint8_t *bitmap);
Display a full bitmap.
bitmap contains only the visible pixels of the display, excluding any blind gaps

void flipdot_update_frame(const uint8_t *frame);
Update the internal frame buffer and flip only the difference to the last frame.
frame contains all pixels shifted into the display registers, including blind gaps between horizontal modules

void flipdot_update_bitmap(const uint8_t *bitmap);
Update the internal frame buffer and flip only the difference to the last frame.
bitmap contains only the visible pixels of the display, excluding any blind gaps

void flipdot_bitmap_to_frame(const uint8_t *bitmap, flipdot_frame_t *frame);
void flipdot_frame_to_bitmap(const uint8_t *frame, flipdot_bitmap_t *bitmap);
Convert between bitmap and frame format by adding or removing blind gaps