FW3X: multiple upgrades...

- upgraded to DSM: lower lows, *much* smoother ramp
- made lows more efficient with underclocking
- fixed party strobe being too blurry
- calibrated UI speed / bogomips multiplier
- added readme to document this hardware's multiple quirks

1 files changed, 59 insertions, 9 deletions

diff --git a/hw/lumintop/fw3x-lume1/hwdef.c b/hw/lumintop/fw3x-lume1/hwdef.c
index 71cd799..0a8a62e 100644
--- a/hw/lumintop/fw3x-lume1/hwdef.c
+++ b/hw/lumintop/fw3x-lume1/hwdef.c
@@ -1,10 +1,11 @@
-// FW3X Lume1 PWM helper functions
+// FW3X Lume1 helper functions
 // Copyright (C) 2023 Selene ToyKeeper
 // SPDX-License-Identifier: GPL-3.0-or-later
 #pragma once
 
 #include "fsm/chan-rgbaux.c"
 
+
 void set_level_zero();
 
 void set_level_main(uint8_t level);
@@ -21,6 +22,12 @@ Channel channels[] = {
 
 
 void set_level_zero() {
+    // disable timer overflow interrupt
+    // (helps improve button press handling from Off state)
+    DSM_INTCTRL &= ~DSM_OVF_bm;
+
+    // turn off all LEDs
+    ch1_dsm_lvl = 0;
     CH1_PWM = 0;
     CH2_PWM = 0;
     PWM_CNT = 0;  // reset phase
@@ -29,19 +36,49 @@ void set_level_zero() {
 
 // single set of LEDs with 2 stacked power channels, regulated + DD FET
 void set_level_main(uint8_t level) {
-    CH1_ENABLE_PORT |= (1 << CH1_ENABLE_PIN);  // enable regulator
+    if (level == actual_level - 1) return;  // prevent flicker on no-op
 
-    PWM_DATATYPE ch1_pwm = PWM_GET(pwm1_levels, level);
-    PWM_DATATYPE ch2_pwm = PWM_GET(pwm2_levels, level);
+    PWM1_DATATYPE ch1 = PWM1_GET(level);
+    PWM2_DATATYPE ch2 = PWM2_GET(level);
 
-    CH1_PWM = ch1_pwm;
-    CH2_PWM = ch2_pwm;
+    // set delta-sigma soft levels
+    ch1_dsm_lvl = ch1;
+
+    // set hardware PWM levels and init dsm loop
+    CH1_PWM = ch1_pwm = ch1 >> 7;
+    CH2_PWM =           ch2;
+
+    // enable timer overflow interrupt so DSM can work
+    DSM_INTCTRL |= DSM_OVF_bm;
 
     // force reset phase when turning on from zero
     // (for faster, more consistent initial response)
     if (! actual_level) PWM_CNT = 0;
+
+    // don't enable ch1 and ch2 at the same time
+    if (ch2) CH1_ENABLE_PORT &= ~(1 << CH1_ENABLE_PIN);  // disable regulator
+    else CH1_ENABLE_PORT |= (1 << CH1_ENABLE_PIN);  // enable regulator
+}
+
+// delta-sigma modulation of PWM outputs
+// happens on each Timer overflow (every 512 cpu clock cycles)
+// uses 8-bit pwm w/ 7-bit dsm (0b 0PPP PPPP PDDD DDDD)
+ISR(DSM_vect) {
+    // set new hardware values first,
+    // for best timing (reduce effect of interrupt jitter)
+    CH1_PWM = ch1_pwm;
+
+    // calculate next values, now that timing matters less
+
+    // accumulate error
+    ch1_dsm += (ch1_dsm_lvl & 0x007f);
+    // next PWM = base PWM value + carry bit
+    ch1_pwm  = (ch1_dsm_lvl >> 7) + (ch1_dsm > 0x7f);
+    // clear carry bit
+    ch1_dsm &= 0x7f;
 }
 
+
 bool gradual_tick_main(uint8_t gt) {
     // 150/150 is full FET + zero regulated,
     // 149/150 is zero FET + full regulated,
@@ -51,10 +88,23 @@ bool gradual_tick_main(uint8_t gt) {
         return true;
     }
 
-    PWM_DATATYPE pwm1 = PWM_GET(pwm1_levels, gt);
-    GRADUAL_ADJUST_SIMPLE(pwm1, CH1_PWM);
+    PWM1_DATATYPE ch1 = PWM1_GET(gt);
 
-    if (pwm1 == CH1_PWM) return true;  // done
+    // adjust multiple times based on current brightness
+    // (so it adjusts faster/coarser when bright, slower/finer when dim)
+
+    // higher shift = slower/finer adjustments
+    const uint8_t shift = 9;  // ((255 << 7) >> 9) = 63 max
+    uint8_t steps;
+
+    steps = ch1_dsm_lvl >> shift;
+    for (uint8_t i=0; i<=steps; i++)
+        GRADUAL_ADJUST_SIMPLE(ch1, ch1_dsm_lvl);
+
+    if ((ch1 == ch1_dsm_lvl)
+       ) {
+        return true;  // done
+    }
     return false;  // not done yet
 }