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enable-1mhz-correct-visually #159

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d82646f
feat(1mhz): F_CPU-derived timing + divide-elimination + HSV→RGB LUT +…
livingkurt Jun 19, 2026
5d907ce
feat(1mhz): Optimize performance for 1MHz CPU speed by reducing divis…
livingkurt Jun 19, 2026
79027f1
Update global brightness settings in test 0506 to enhance sleep mode …
livingkurt Jun 20, 2026
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10 changes: 8 additions & 2 deletions Helios/Colortypes.cpp
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Expand Up @@ -369,8 +369,14 @@ RGBColor hsv_to_rgb_generic(const HSVColor &rhs)
return col;
}

region = rhs.hue / 43;
remainder = ((rhs.hue - (region * 43)) * 6);
// At 1MHz the AVR has ~8x fewer cycles per tick. The original division
// (hue / 43) compiles to a ~200-cycle software divide on AVR. Replacing it
// with a branchless compare tree + a LUT subtraction cuts this to ~10 cycles.
static const uint8_t region_base[6] = { 0, 43, 86, 129, 172, 215 };
region = (rhs.hue < 86) ? ((rhs.hue < 43) ? 0 : 1)
: (rhs.hue < 172) ? ((rhs.hue < 129) ? 2 : 3)
: ((rhs.hue < 215) ? 4 : 5);
remainder = ((rhs.hue - region_base[region]) * 6);

// extraneous casts to uint16_t are to prevent overflow
p = (uint8_t)(((uint16_t)(rhs.val) * (255 - rhs.sat)) >> 8);
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9 changes: 8 additions & 1 deletion Helios/Helios.cpp
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Expand Up @@ -328,7 +328,14 @@ void Helios::handle_state_modes()
uint32_t holdDur = Button::holdDuration();
// calculate a magnitude which corresponds to how many times past the MENU_HOLD_TIME
// the user has held the button, so 0 means haven't held fully past one yet, etc
uint8_t magnitude = (uint8_t)(holdDur / MENU_HOLD_TIME);
// At 1MHz, 32-bit division is a ~240-cycle software routine called every tick.
// Unrolling into threshold comparisons eliminates the divide entirely.
uint8_t magnitude =
(holdDur >= (uint32_t)(MENU_HOLD_TIME * 5)) ? 5 :
(holdDur >= (uint32_t)(MENU_HOLD_TIME * 4)) ? 4 :
(holdDur >= (uint32_t)(MENU_HOLD_TIME * 3)) ? 3 :
(holdDur >= (uint32_t)(MENU_HOLD_TIME * 2)) ? 2 :
(holdDur >= (uint32_t)(MENU_HOLD_TIME * 1)) ? 1 : 0;
// whether the user has held the button longer than a short click
bool heldPast = (holdDur > SHORT_CLICK_THRESHOLD);

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9 changes: 7 additions & 2 deletions Helios/TimeControl.cpp
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Expand Up @@ -103,8 +103,13 @@ uint32_t Time::microseconds()
// should always just rely on the current tick to perform operations
uint8_t oldSREG = SREG;
cli();
// multiply by 8 early to avoid floating point math or division
uint32_t micros = (timer0_overflow_count * (256 * 8)) + (TCNT0 * 8);
// Scale overflow count and timer ticks by the number of microseconds each Timer0
// tick represents at the configured CPU speed. Timer0 runs at F_CPU/1 (no prescaler),
// so each tick = (1/F_CPU) seconds = (1000000/F_CPU) microseconds.
// The factor (64000000UL/F_CPU) bakes that in as an integer: 8 @ 8MHz, 64 @ 1MHz,
// 4 @ 16MHz. Using F_CPU here means this formula automatically adapts when
// CPU_SPEED is changed in the Makefile — no manual constant updates needed.
uint32_t micros = (timer0_overflow_count * (256 * (64000000UL / F_CPU))) + (TCNT0 * (64000000UL / F_CPU));
SREG = oldSREG;
// then shift right to counteract the multiplication by 8
return micros >> 6;
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10 changes: 7 additions & 3 deletions Helios/Timer.cpp
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Expand Up @@ -48,9 +48,13 @@ bool Timer::alarm()
if (timeDiff == 0) {
return true;
}
// if the current alarm duration is not a multiple of the current tick
if (m_alarm && (timeDiff % m_alarm) != 0) {
// then the alarm was not hit
// At 1MHz a 32-bit software modulo costs ~240 AVR cycles — called every tick,
// that's a significant fraction of budget. The original (timeDiff % m_alarm == 0)
// was checking if the alarm interval divided evenly, but because start() always
// resets m_startTime the moment the alarm fires, timeDiff simply counts up from
// 0 to m_alarm and then resets. So "has the alarm fired?" is just (timeDiff >= m_alarm),
// no division needed.
if (timeDiff < (int32_t)m_alarm) {
return false;
}
// update the start time of the timer
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8 changes: 6 additions & 2 deletions HeliosEmbedded/Makefile
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Expand Up @@ -84,7 +84,9 @@ AVRDUDE_FLAGS = $(AVRDUDE_CONFIG_FLAG) \
-P$(AVRDUDE_PORT) \
-b$(AVRDUDE_BAUDRATE) \
-v \
-B1
-B10 # ISP bit-clock period in microseconds. Was -B1 (1µs = 1MHz ISP clock).
# At 1MHz CPU the target can only accept an ISP clock up to F_CPU/4 = 250kHz,
# so -B1 overclocked the ISP bus and caused upload failures. -B10 = 100kHz ISP.

# -v -- Verbose output - display detailed progress
# -B1 -- Bit clock period (in microseconds) - sets programming speed
Expand All @@ -96,7 +98,9 @@ AVRDUDE_FLAGS = $(AVRDUDE_CONFIG_FLAG) \
### COMPILER FLAGS ####
#######################

CPU_SPEED = 8000000L
CPU_SPEED = 1000000L # 1MHz internal oscillator. Drops power draw significantly vs 8MHz.
# Requires fuse H:0xDF L:0x62 (CKDIV8 enabled, SUT_CKSEL=internal 8MHz / 8).
# Run `make set_fuses` after changing this value.

# the port for serial upload
SERIAL_PORT = COM11
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26 changes: 13 additions & 13 deletions tests/tests/0008_Cycle_Color_Slots_Exit.test
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Expand Up @@ -3311,6 +3311,19 @@ D200FF
000000
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FF0000
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FF3C00
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FF7800
FF7800
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0000FF
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D200FF
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000000
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Expand Down Expand Up @@ -3599,16 +3612,3 @@ D200FF
000000
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2 changes: 1 addition & 1 deletion tests/tests/0125_From_First_Mode_Enter_Conjure_Mode.test
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Expand Up @@ -3805,7 +3805,6 @@ D200FF
3C1C00
000000
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Expand Down Expand Up @@ -4105,3 +4104,4 @@ D200FF
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2 changes: 1 addition & 1 deletion tests/tests/0153_Cycle_Master_Reset_Options.test
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Expand Up @@ -3604,7 +3604,7 @@ D200FF
003C00
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2 changes: 1 addition & 1 deletion tests/tests/0154_Cycle_Global_Brightness_Options.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
00003C
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0A0A0A
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2 changes: 1 addition & 1 deletion tests/tests/0155_Navigate_to_Exit_Master_Reset.test
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Expand Up @@ -3604,7 +3604,7 @@ D200FF
003C00
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2 changes: 1 addition & 1 deletion tests/tests/0156_Navigate_to_Master_Reset_Option.test
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Expand Up @@ -3604,7 +3604,7 @@ D200FF
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2 changes: 1 addition & 1 deletion tests/tests/0157_Navigate_to_Full_Brightness_Option.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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2 changes: 1 addition & 1 deletion tests/tests/0158_Navigate_to_Medium_Brightness_Option.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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2 changes: 1 addition & 1 deletion tests/tests/0159_Navigate_to_Low_Brightness_Option.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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8 changes: 4 additions & 4 deletions tests/tests/0252_Set_Global_Brightness_to_High.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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Expand Down Expand Up @@ -4906,9 +4906,6 @@ D200FF
000000
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Expand Down Expand Up @@ -5207,6 +5204,9 @@ D200FF
000000
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8 changes: 4 additions & 4 deletions tests/tests/0253_Set_Global_Brightness_to_Low.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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Expand Down Expand Up @@ -5508,9 +5508,6 @@ D200FF
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Expand Down Expand Up @@ -5809,6 +5806,9 @@ D200FF
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8 changes: 4 additions & 4 deletions tests/tests/0254_Set_Global_Brightness_to_Low_then_Mid.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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Expand Down Expand Up @@ -5508,9 +5508,6 @@ D200FF
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Expand Down Expand Up @@ -5809,6 +5806,9 @@ D200FF
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8 changes: 4 additions & 4 deletions tests/tests/0255_Set_High_Medium_Low_Lowest_Global_Brightness.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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Expand Down Expand Up @@ -4906,9 +4906,6 @@ D200FF
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Expand Down Expand Up @@ -5207,6 +5204,9 @@ D200FF
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2 changes: 1 addition & 1 deletion tests/tests/0256_Set_Global_Brightness_to_Lowest.test
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Expand Up @@ -4604,7 +4604,7 @@ D200FF
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