Data East / Sega support #3
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mkalkbrenner
requested changes
Nov 4, 2025
src/dmd_reader.c
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| lcd_width = 128; | ||
| lcd_height = 32; | ||
| lcd_bitsperpixel = 4; // data east sega is 2bpp |
src/dmd_reader.c
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| dmd_pio = pio0; | ||
| offset = pio_add_program(dmd_pio, &dmd_reader_desega_program); | ||
| dmd_sm = pio_claim_unused_sm(dmd_pio, true); | ||
| dmd_reader_whitestar_program_init(dmd_pio, dmd_sm, offset); |
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dmd_reader_desega_program_init
src/dmd_interface_whitestar.pio
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| wait 0 gpio DOTCLK ; falling edge | ||
| wait 1 gpio DOTCLK ; raising edge | ||
| in null 2 ; padding | ||
| ;in null 2 ; padding |
src/dmd_interface_whitestar.pio
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| in null 2 ; padding | ||
| ;in null 2 ; padding | ||
| in pins 1 ; read pin data | ||
| in null 1 |
src/dmd_interface_whitestar.pio
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| wait 0 gpio DOTCLK ; falling edge | ||
| wait 1 gpio DOTCLK ; raising edge | ||
| in null 3 ; padding | ||
| in null 1 ; padding |
| dotloop1: | ||
| wait 0 gpio DOTCLK ; falling edge | ||
| wait 1 gpio DOTCLK ; raising edge | ||
| in null 2 ; padding |
| wait 1 gpio DOTCLK ; raising edge | ||
| in null 2 ; padding | ||
| in pins 1 ; read pin data | ||
| in null 1 |
| dotloop2: | ||
| wait 0 gpio DOTCLK ; falling edge | ||
| wait 1 gpio DOTCLK ; raising edge | ||
| in null 3 ; padding |
mkalkbrenner
reviewed
Nov 4, 2025
| lcd_planesperframe = 2; // in Whitestar, there's a MSB and a LSB plane | ||
| lcd_lineoversampling = LINEOVERSAMPLING_WHITESTAR; // in Whitestar each line is sent twice | ||
| lcd_mergeplanes = MERGEPLANES_ADDSHIFT; // required for correct 2bpp merge | ||
| //lcd_mergeplanes = MERGEPLANES_ADDSHIFT; // required for correct 2bpp merge |
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Logic is nearly identical to whitestar, except the beginning of a frame detection is different. Looking at the signals there was no clear way to identify the start of a frame. It seems that they fixed this for Whitestar, where ROWDATA clearly shows the beginning of a frame. Unfortunately not the case with DE/Sega.
Display Enable is now used to detect the beginning of a frame instead, but that is measured through checking the length of the GPIO being low.