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Fix long sync pulse was interrupted by spike of blankingLevel #4

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Fix long sync pulse was interrupted by spike of blankingLevel #4

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14 changes: 12 additions & 2 deletions colourpal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,14 @@
#define YDATA_START 43 // line number
#define YDATA_END (YDATA_START + YRESOLUTION*2)

//lines 1-5 with sync info
//lines 6-42 blank
//data start line 43
//data end line 262
//lines 263-309 blank
//lines 310-312 with sync info
//312 last line

// PAL timings - these are here as consts because the division needs to process
// a horizontal line is 64 microseconds
// this HAS to be divisible by 4 to use 32-bit DMA transfers
Expand All @@ -51,6 +59,7 @@
const uint32_t SAMPLES_PER_LINE = 4*((uint32_t)((64 * DAC_FREQ / 1e6)/4)); // this HAS to be a multiple of 4!
const uint32_t SAMPLES_GAP = 4.7 * DAC_FREQ / 1e6; // 312
const uint32_t SAMPLES_SHORT_PULSE = 2.35 * DAC_FREQ / 1e6; // the time of the little blip down mid line
const uint32_t SAMPLES_LONG_PULSE = 23.5 * DAC_FREQ / 1e6; // used in lines 1-3
const uint32_t SAMPLES_HSYNC = 4.7 * DAC_FREQ / 1e6; // horizontal sync duration
const uint32_t SAMPLES_BACK_PORCH = 5.7 * DAC_FREQ / 1e6; // back porch duration
const uint32_t SAMPLES_FRONT_PORCH = 1.7 * DAC_FREQ / 1e6; // front porch duration
Expand Down Expand Up @@ -274,8 +283,9 @@ class ColourPal {
memset(line3_B, levelBlank, SAMPLES_COLOUR);
memset(line4_B, levelBlank, SAMPLES_COLOUR);
memset(line6_B, levelBlank, SAMPLES_COLOUR); // this one is easy, nothing else needed

memset(line1_A + SAMPLES_DEAD_SPACE + SAMPLES_FRONT_PORCH, levelSync, SAMPLES_HSYNC + SAMPLES_BACK_PORCH);

const uint32_t longPulseLengthA = MIN(SAMPLES_LONG_PULSE, SAMPLES_SYNC_PORCHES - SAMPLES_DEAD_SPACE - SAMPLES_FRONT_PORCH);
memset(line1_A + SAMPLES_DEAD_SPACE + SAMPLES_FRONT_PORCH, levelSync, longPulseLengthA);
memset(line4_A + SAMPLES_DEAD_SPACE + SAMPLES_FRONT_PORCH, levelSync, SAMPLES_SHORT_PULSE);
memset( line6odd_A + SAMPLES_DEAD_SPACE + SAMPLES_FRONT_PORCH, levelSync, SAMPLES_HSYNC);
memset(line6even_A + SAMPLES_DEAD_SPACE + SAMPLES_FRONT_PORCH, levelSync, SAMPLES_HSYNC);
Expand Down