mangavalkandClaude Opus 5.5
f1dbc35ebd
- Commands run on '\n' instead of busy-waiting for a byte count, which fixes s/F/T waiting for the next command and P drawing 0xFF garbage - Invalid bitmaps no longer leak their data as commands; bitmap data is streamed so full-screen bitmaps still fit - Store flip time as uint16 with magic marker, validate 50-2000 us - Overflow-safe millis() handling for the periodic refresh - Run the full refresh only after D or when serial is idle, so incoming data is not lost while the redraw blocks - Put the boot refresh measurement behind MEASURE_REFRESH - Fix DEBUG hex output and use F() strings to save RAM - Driver: direct mode now updates the old buffer instead of re-setting the new one Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
3.0 KiB
Arduino Nano: flipdot driver
PlatformIO environment: nano
The Nano is connected directly to the Brose panel electronics. It keeps an 84 × 19 frame buffer and takes drawing commands over serial (115200 baud). It has no clock or network logic.
Behaviour
- Boot: the Nano loads the flip time from EEPROM and flips the whole display on and then off.
display(): compares the new buffer with the last one that was shown and strobes only the dots that changed.- Every 2 minutes (
REFRESH_TIME) it does a full redraw to fix dots that got stuck. A full redraw blocks for about half a second, which is long enough to overflow the 64-byte serial buffer. So it only runs right after aD(the end of a frame, when the ESP is quiet) or when no serial data has arrived for 2 seconds. - Flip pulse length (µs, 50–2000) is set with the
Tcommand and stored in EEPROM, so it is kept after a reboot. The default is 200 µs.
Debug options
Uncomment these at the top of main.cpp:
| Define | Effect |
|---|---|
DEBUG |
Print unknown command bytes on the serial port |
MEASURE_REFRESH |
At boot, time a full redraw and print the duration in ms |
Serial protocol
Each command is one ASCII line that ends with \n (\r is ignored). The Nano
collects a whole line before it runs the command. If a line is broken or unknown, it is
skipped and the next line starts clean. Coordinates are 2-digit hex. Color is 0
(black) or 1 (yellow). The ESP32 driver (ESPSERIAL) only uses s, S, F, D and
T.
| Cmd | Format | Meaning |
|---|---|---|
s |
sXXYYc |
Set pixel in the buffer |
S |
SXXYYc |
Set pixel and flip it right away (direct mode) |
F |
Fc |
Fill the whole buffer |
D |
D |
Push the buffer to the display (changed dots only) |
P |
PXXYYcsTEXT |
Print text at (XX,YY), color c, size s. A literal \n (backslash, n) in TEXT starts a new line. The whole line can be at most 64 characters. |
B |
BXXYYWWHHcHEX... |
Draw a bitmap. WW must be a multiple of 4. Pixel data is one hex digit per 4 pixels, row by row. The data is drawn while it arrives, so it is not limited to 64 characters. |
R |
R |
Print the buffer as ASCII art on the serial port |
T |
Tnnn |
Set the flip pulse length in µs (decimal, 50–2000), stored in EEPROM |
Invalid commands get a reply that starts with ERR: on the Nano's TX pin.
Example (what the ESP32 sends for one pixel and a refresh):
s0a051
D
Wiring (default pinout)
The pins are defined in lib/BROSE9323/BROSE9323.h.
If you use the PLCC adapter board, build with -D FLIPDOT_PLCC_ADAPTER to switch to its
pinout.
| Signal | Nano pin |
|---|---|
| ENABLE | D7 |
| ADDR_0 / 1 / 2 (panel select) | D3 / D5 / D6 |
| COL_DATA | D4 |
| COL_0 … COL_4 | D8, D10, D9, D11, D12 |
| ROW_0 … ROW_4 | A3, A4, A2, A0, A1 |
| ROW_RESET | D13 |
| ROW_SET | A5 |
| Serial RX | D0 (from ESP32 TX) |