converted noctigon-dm11-boost to use PWM+DSM, and recalibrated timing for delays + smooth steps

Anduril has gradually gotten faster over the years, apparently, so it
needed longer delays to get accurate-ish timing for beacon and other modes.
Adding DSM also changes the timing perceptibly, so I made it possible to
calibrate the delay fudge factor on a per-build basis.

7 files changed, 126 insertions, 53 deletions

diff --git a/hwdef-noctigon-dm11-boost.c b/hwdef-noctigon-dm11-boost.c
index 08e2798..932323a 100644
--- a/hwdef-noctigon-dm11-boost.c
+++ b/hwdef-noctigon-dm11-boost.c
@@ -1,11 +1,11 @@
 // Noctigon DM11 (boost driver) PWM helper functions
 // Copyright (C) 2023 Selene ToyKeeper
 // SPDX-License-Identifier: GPL-3.0-or-later
-
 #pragma once
 
 #include "chan-rgbaux.c"
 
+
 void set_level_zero();
 
 void set_level_main(uint8_t level);
@@ -22,6 +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;
     PWM_CNT = 0;  // reset phase
     CH1_ENABLE_PORT  &= ~(1 << CH1_ENABLE_PIN );  // disable opamp
@@ -30,28 +36,59 @@ void set_level_zero() {
 
 // single set of LEDs with single power channel, boost
 void set_level_main(uint8_t level) {
-    CH1_ENABLE_PORT  |= (1 << CH1_ENABLE_PIN );  // enable opamp
-    CH1_ENABLE_PORT2 |= (1 << CH1_ENABLE_PIN2);  // enable PMIC
+    PWM_DATATYPE ch1 = PWM_GET(pwm1_levels, level);
 
-    PWM_DATATYPE ch1_pwm = PWM_GET(pwm1_levels, level);
-    // pulse frequency modulation, a.k.a. dynamic PWM
-    uint16_t top = PWM_GET16(pwm_tops, level);
+    // set delta-sigma soft levels
+    ch1_dsm_lvl = ch1;
+
+    // set hardware PWM levels and init dsm loop
+    CH1_PWM = ch1_pwm = ch1 >> 7;
+
+    // enable timer overflow interrupt so DSM can work
+    DSM_INTCTRL |= DSM_OVF_bm;
 
-    CH1_PWM = ch1_pwm;
-    // wait to sync the counter and avoid flashes
-    while(actual_level && (PWM_CNT > (top - 32))) {}
-    PWM_TOP = top;
     // force reset phase when turning on from zero
     // (because otherwise the initial response is inconsistent)
     if (! actual_level) PWM_CNT = 0;
+
+    CH1_ENABLE_PORT  |= (1 << CH1_ENABLE_PIN );  // enable opamp
+    CH1_ENABLE_PORT2 |= (1 << CH1_ENABLE_PIN2);  // enable PMIC
 }
 
+// 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) {
-    PWM_DATATYPE pwm1 = PWM_GET(pwm1_levels, gt);
+    PWM_DATATYPE ch1 = PWM_GET(pwm1_levels, gt);
+
+    // 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;
 
-    GRADUAL_ADJUST_SIMPLE(pwm1, CH1_PWM);
+    steps = ch1_dsm_lvl >> shift;
+    for (uint8_t i=0; i<=steps; i++)
+        GRADUAL_ADJUST_SIMPLE(ch1, ch1_dsm_lvl);
 
-    if (   (pwm1 == CH1_PWM)
+    if ((ch1 == ch1_dsm_lvl)
        ) {
         return true;  // done
     }
diff --git a/hwdef-noctigon-dm11-boost.h b/hwdef-noctigon-dm11-boost.h
index 4453bc7..d56a5f5 100644
--- a/hwdef-noctigon-dm11-boost.h
+++ b/hwdef-noctigon-dm11-boost.h
@@ -31,7 +31,7 @@
  *
  * Main LED power uses one pin to turn the Opamp on/off,
  * and one pin to control Opamp power level.
- * Linear brightness control uses the power level pin, with dynamic PWM.
+ * Regulated brightness control uses the power level pin, with PWM+DSM.
  * The on/off pin is only used to turn the main LED on and off,
  * not to change brightness.
  */
@@ -62,35 +62,46 @@ enum CHANNEL_MODES {
 //#define CHANNEL_MODE_ARGS     0,0,0,0,0,0,0,0
 
 
-#define PWM_CHANNELS 1  // old, remove this
+#define PWM_CHANNELS  1  // old, remove this
 
-#define PWM_BITS      16        // dynamic 16-bit, but never goes over 255
-#define PWM_GET       PWM_GET8
-#define PWM_DATATYPE  uint16_t  // is used for PWM_TOPS (which goes way over 255)
-#define PWM_DATATYPE2 uint16_t  // only needs 32-bit if ramp values go over 255
-#define PWM1_DATATYPE uint8_t   // regulated ramp
+#define PWM_BITS      16        // 0 to 32640 (0 to 255 PWM + 0 to 127 DSM) at constant kHz
+#define PWM_GET       PWM_GET16
+#define PWM_DATATYPE  uint16_t
+#define PWM_DATATYPE2 uint32_t  // only needs 32-bit if ramp values go over 255
+#define PWM1_DATATYPE uint16_t  // 15-bit PWM+DSM ramp
 
 #define PWM_TOP       ICR1   // holds the TOP value for variable-resolution PWM
-#define PWM_TOP_INIT  255    // highest value used in top half of ramp
-#define PWM_CNT       TCNT1  // for dynamic PWM, reset phase
+#define PWM_TOP_INIT  255
+#define PWM_CNT       TCNT1  // for checking / resetting phase
+// (max is (255 << 7), because it's 8-bit PWM plus 7 bits of DSM)
+#define DSM_TOP       (255<<7) // 15-bit resolution leaves 1 bit for carry
+
+// timer interrupt for DSM
+#define DSM_vect     TIMER1_OVF_vect
+#define DSM_INTCTRL  TIMSK
+#define DSM_OVF_bm   (1<<TOIE1)
+
+#define DELAY_FACTOR 90  // less time in delay() because more time spent in interrupts
 
 // regulated channel
-#define CH1_PIN PB3            // pin 16, Opamp reference
-#define CH1_PWM OCR1A          // OCR1A is the output compare register for PB3
+uint16_t ch1_dsm_lvl;
+uint8_t ch1_pwm, ch1_dsm;
+#define CH1_PIN          PB3    // pin 16, Opamp reference
+#define CH1_PWM          OCR1A  // OCR1A is the output compare register for PB3
 
-#define CH1_ENABLE_PIN  PB0    // pin 19, Opamp power
-#define CH1_ENABLE_PORT PORTB  // control port for PB0
+#define CH1_ENABLE_PIN   PB0    // pin 19, Opamp power
+#define CH1_ENABLE_PORT  PORTB  // control port for PB0
 
 #define CH1_ENABLE_PIN2  PC0   // pin 15, boost PMIC enable
 #define CH1_ENABLE_PORT2 PORTC // control port for PC0
 
 // e-switch
-#define SWITCH_PIN   PA7    // pin 20
-#define SWITCH_PCINT PCINT7 // pin 20 pin change interrupt
-#define SWITCH_PCIE  PCIE0  // PCIE0 is for PCINT[7:0]
-#define SWITCH_PCMSK PCMSK0 // PCMSK0 is for PCINT[7:0]
-#define SWITCH_PORT  PINA   // PINA or PINB or PINC
-#define SWITCH_PUE   PUEA   // pullup group A
+#define SWITCH_PIN   PA7     // pin 20
+#define SWITCH_PCINT PCINT7  // pin 20 pin change interrupt
+#define SWITCH_PCIE  PCIE0   // PCIE0 is for PCINT[7:0]
+#define SWITCH_PCMSK PCMSK0  // PCMSK0 is for PCINT[7:0]
+#define SWITCH_PORT  PINA    // PINA or PINB or PINC
+#define SWITCH_PUE   PUEA    // pullup group A
 #define PCINT_vect   PCINT0_vect  // ISR for PCINT[7:0]
 
 #define USE_VOLTAGE_DIVIDER  // use a dedicated pin, not VCC, because VCC input is flattened
@@ -163,21 +174,28 @@ inline void hwdef_setup() {
     // configure PWM
     // Setup PWM. F_pwm = F_clkio / 2 / N / TOP, where N = prescale factor, TOP = top of counter
     // pre-scale for timer: N = 1
+    // PWM for both channels
     // WGM1[3:0]: 1,0,1,0: PWM, Phase Correct, adjustable (DS table 12-5)
+    // WGM1[3:0]: 1,1,1,0: PWM, Fast, adjustable (DS table 12-5)
     // CS1[2:0]:    0,0,1: clk/1 (No prescaling) (DS table 12-6)
     // COM1A[1:0]:    1,0: PWM OC1A in the normal direction (DS table 12-4)
-    // COM1B[1:0]:    0,0: PWM OC1B disabled (DS table 12-4)
+    // COM1B[1:0]:    1,0: PWM OC1B in the normal direction (DS table 12-4)
     TCCR1A = (1<<WGM11)  | (0<<WGM10)   // adjustable PWM (TOP=ICR1) (DS table 12-5)
            | (1<<COM1A1) | (0<<COM1A0)  // PWM 1A in normal direction (DS table 12-4)
-           | (0<<COM1B1) | (0<<COM1B0)  // PWM 1B disabled (DS table 12-4)
+           | (1<<COM1B1) | (0<<COM1B0)  // PWM 1B in normal direction (DS table 12-4)
            ;
     TCCR1B = (0<<CS12)   | (0<<CS11) | (1<<CS10)  // clk/1 (no prescaling) (DS table 12-6)
+           //| (1<<WGM13)  | (1<<WGM12)  // fast adjustable PWM (DS table 12-5)
            | (1<<WGM13)  | (0<<WGM12)  // phase-correct adjustable PWM (DS table 12-5)
            ;
 
     // set PWM resolution
     PWM_TOP = PWM_TOP_INIT;
 
+    // set up interrupt for delta-sigma modulation
+    // (moved to hwdef.c functions so it can be enabled/disabled based on ramp level)
+    //DSM_INTCTRL |= DSM_OVF_bm;  // interrupt once for each timer cycle
+
     // set up e-switch
     SWITCH_PUE = (1 << SWITCH_PIN);  // pull-up for e-switch
     SWITCH_PCMSK = (1 << SWITCH_PCINT);  // enable pin change interrupt
diff --git a/hwdef-noctigon-m44.h b/hwdef-noctigon-m44.h
index a41ea79..094e555 100644
--- a/hwdef-noctigon-m44.h
+++ b/hwdef-noctigon-m44.h
@@ -65,7 +65,7 @@ enum channel_modes_e {
 
 #define PWM_CHANNELS  1  // old, remove this
 
-#define PWM_BITS      16     // 0 to 32640 (0 to 255 PWM + 0 to 127 DSM) at constant kHz
+#define PWM_BITS      16        // 0 to 32640 (0 to 255 PWM + 0 to 127 DSM) at constant kHz
 #define PWM_GET       PWM_GET16
 #define PWM_DATATYPE  uint16_t
 #define PWM_DATATYPE2 uint32_t  // only needs 32-bit if ramp values go over 255
@@ -105,8 +105,8 @@ uint8_t ch2_pwm, ch2_dsm;
 // e-switch
 #define SWITCH_PIN   PA7     // pin 20
 #define SWITCH_PCINT PCINT7  // pin 20 pin change interrupt
-#define SWITCH_PCIE  PCIE0   // PCIE1 is for PCINT[7:0]
-#define SWITCH_PCMSK PCMSK0  // PCMSK1 is for PCINT[7:0]
+#define SWITCH_PCIE  PCIE0   // PCIE0 is for PCINT[7:0]
+#define SWITCH_PCMSK PCMSK0  // PCMSK0 is for PCINT[7:0]
 #define SWITCH_PORT  PINA    // PINA or PINB or PINC
 #define SWITCH_PUE   PUEA    // pullup group A
 #define PCINT_vect   PCINT0_vect  // ISR for PCINT[7:0]
@@ -178,14 +178,14 @@ inline void hwdef_setup() {
     // CS1[2:0]:    0,0,1: clk/1 (No prescaling) (DS table 12-6)
     // COM1A[1:0]:    1,0: PWM OC1A in the normal direction (DS table 12-4)
     // COM1B[1:0]:    1,0: PWM OC1B in the normal direction (DS table 12-4)
-    TCCR1A  = (1<<WGM11)  | (0<<WGM10)   // adjustable PWM (TOP=ICR1) (DS table 12-5)
-            | (1<<COM1A1) | (0<<COM1A0)  // PWM 1A in normal direction (DS table 12-4)
-            | (1<<COM1B1) | (0<<COM1B0)  // PWM 1B in normal direction (DS table 12-4)
-            ;
-    TCCR1B  = (0<<CS12)   | (0<<CS11) | (1<<CS10)  // clk/1 (no prescaling) (DS table 12-6)
-            //| (1<<WGM13)  | (1<<WGM12)  // fast adjustable PWM (DS table 12-5)
-            | (1<<WGM13)  | (0<<WGM12)  // phase-correct adjustable PWM (DS table 12-5)
-            ;
+    TCCR1A = (1<<WGM11)  | (0<<WGM10)   // adjustable PWM (TOP=ICR1) (DS table 12-5)
+           | (1<<COM1A1) | (0<<COM1A0)  // PWM 1A in normal direction (DS table 12-4)
+           | (1<<COM1B1) | (0<<COM1B0)  // PWM 1B in normal direction (DS table 12-4)
+           ;
+    TCCR1B = (0<<CS12)   | (0<<CS11) | (1<<CS10)  // clk/1 (no prescaling) (DS table 12-6)
+           //| (1<<WGM13)  | (1<<WGM12)  // fast adjustable PWM (DS table 12-5)
+           | (1<<WGM13)  | (0<<WGM12)  // phase-correct adjustable PWM (DS table 12-5)
+           ;
 
     // set PWM resolution
     PWM_TOP = PWM_TOP_INIT;
diff --git a/spaghetti-monster/anduril/cfg-noctigon-dm11-boost.h b/spaghetti-monster/anduril/cfg-noctigon-dm11-boost.h
index 5c5db00..2174fdb 100644
--- a/spaghetti-monster/anduril/cfg-noctigon-dm11-boost.h
+++ b/spaghetti-monster/anduril/cfg-noctigon-dm11-boost.h
@@ -14,18 +14,31 @@
 // - boost: 8A?
 // - DD FET: none (can't do DD on a boost driver)
 
+#if 0  // old, dynamic PWM method
 // level_calc.py 5.01 1 149 7135 1 0.3 1740 --pwm dyn:78:16384:255
 // (plus a 0 at the beginning for moon)
 #define PWM1_LEVELS 0,1,1,1,2,3,3,4,5,6,7,8,9,10,11,13,14,16,17,19,21,23,25,27,29,31,34,36,39,42,44,47,50,53,57,60,63,67,70,74,77,81,85,88,92,96,99,103,107,110,113,117,120,123,126,128,130,133,134,136,137,137,137,137,136,135,133,130,126,122,117,111,104,96,87,76,65,52,38,22,23,25,26,27,28,29,30,32,33,34,36,37,39,40,42,43,45,47,49,51,53,55,57,59,61,63,66,68,70,73,76,78,81,84,87,90,93,96,99,103,106,110,113,117,121,125,129,133,137,142,146,151,155,160,165,170,175,181,186,192,197,203,209,215,222,228,234,241,248,255
 #define PWM_TOPS 16383,16383,12404,8140,11462,14700,11041,12947,13795,14111,14124,13946,13641,13248,12791,13418,12808,13057,12385,12428,12358,12209,12000,11746,11459,11147,11158,10793,10708,10576,10173,9998,9800,9585,9527,9278,9023,8901,8634,8486,8216,8053,7881,7615,7440,7261,7009,6832,6656,6422,6196,6031,5819,5615,5419,5190,4973,4803,4571,4386,4179,3955,3745,3549,3340,3145,2940,2729,2513,2312,2109,1903,1697,1491,1286,1070,871,662,459,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255
-
 #define MAX_1x7135 150
 #define DEFAULT_LEVEL 70
 #define MIN_THERM_STEPDOWN 80  // must be > end of dynamic PWM range
 #define HALFSPEED_LEVEL 12
 #define QUARTERSPEED_LEVEL 4
+#endif
+
+// delta-sigma modulated PWM (0b0HHHHHHHHLLLLLLL = 0, 8xHigh, 7xLow bits)
+// level_calc.py 5.01 1 150 7135 0 0.2 2000 --pwm 32640
+// (max is (255 << 7), because it's 8-bit PWM plus 7 bits of DSM)
+#define PWM1_LEVELS 0,1,2,3,4,5,6,7,9,10,12,14,17,19,22,25,28,32,36,41,45,50,56,62,69,76,84,92,101,110,121,132,143,156,169,184,199,215,232,251,270,291,313,336,360,386,414,442,473,505,539,574,612,651,693,736,782,829,880,932,987,1045,1105,1168,1233,1302,1374,1449,1527,1608,1693,1781,1873,1969,2068,2172,2279,2391,2507,2628,2753,2883,3018,3158,3303,3454,3609,3771,3938,4111,4289,4475,4666,4864,5068,5280,5498,5724,5957,6197,6445,6701,6965,7237,7518,7808,8106,8413,8730,9056,9392,9737,10093,10459,10835,11223,11621,12031,12452,12884,13329,13786,14255,14737,15232,15741,16262,16798,17347,17911,18489,19082,19691,20314,20954,21609,22281,22969,23674,24397,25137,25895,26671,27465,28279,29111,29963,30835,31727,32640
+#define MIN_THERM_STEPDOWN 50
+#define DEFAULT_LEVEL 70
+#define MAX_1x7135 150
+// always run at 1/4th speed, because 4 kHz PWM is enough for this circuit
+// and speed changes make a big visible bump
+#define HALFSPEED_LEVEL     255
+#define QUARTERSPEED_LEVEL  255
 
-#define RAMP_SMOOTH_FLOOR 10  // low levels may be unreliable
+#define RAMP_SMOOTH_FLOOR 1  // low levels may be unreliable
 #define RAMP_SMOOTH_CEIL  130
 // 10, 30, 50, [70], 90, 110, 130
 // Nichia B35 model: (0.56), 1.4, 8.4, 34.5, [102], 250, 500, 860, (1300) lm
diff --git a/spaghetti-monster/anduril/smooth-steps.c b/spaghetti-monster/anduril/smooth-steps.c
index d907bc1..b8664bd 100644
--- a/spaghetti-monster/anduril/smooth-steps.c
+++ b/spaghetti-monster/anduril/smooth-steps.c
@@ -23,12 +23,12 @@ void smooth_steps_iter() {
         uint8_t this = diff / smooth_steps_speed;
         if (!this) this = 1;
         set_level(actual_level + this);
-        nice_delay_ms(10);
+        nice_delay_ms(9);
     } else {
         // ramp-linear descent
         // (jump by 1 on each frame, frame rate gives constant total time)
         uint8_t diff = smooth_steps_start - smooth_steps_target;
-        uint16_t delay = 1 + (26 * smooth_steps_speed / diff);
+        uint16_t delay = 1 + (22 * smooth_steps_speed / diff);
         set_level(actual_level - 1);
         // TODO? if delay < one PWM cycle, this can look a little weird
         nice_delay_ms(delay);
diff --git a/spaghetti-monster/fsm-events.c b/spaghetti-monster/fsm-events.c
index ffa93d1..6987ae2 100644
--- a/spaghetti-monster/fsm-events.c
+++ b/spaghetti-monster/fsm-events.c
@@ -127,7 +127,7 @@ uint8_t nice_delay_ms(uint16_t ms) {
         uint8_t level = actual_level;  // volatile, avoid repeat access
         if (level < QUARTERSPEED_LEVEL) {
             clock_prescale_set(clock_div_4);
-            _delay_loop_2(BOGOMIPS*90/100/4);
+            _delay_loop_2(BOGOMIPS*DELAY_FACTOR/100/4);
         }
         //else if (level < HALFSPEED_LEVEL) {
         //    clock_prescale_set(clock_div_2);
@@ -135,7 +135,7 @@ uint8_t nice_delay_ms(uint16_t ms) {
         //}
         else {
             clock_prescale_set(clock_div_1);
-            _delay_loop_2(BOGOMIPS*90/100);
+            _delay_loop_2(BOGOMIPS*DELAY_FACTOR/100);
         }
         // restore regular clock speed
         clock_prescale_set(clock_div_1);
@@ -143,13 +143,13 @@ uint8_t nice_delay_ms(uint16_t ms) {
         // underclock MCU to save power
         clock_prescale_set(clock_div_4);
         // wait
-        _delay_loop_2(BOGOMIPS*90/100/4);
+        _delay_loop_2(BOGOMIPS*DELAY_FACTOR/100/4);
         // restore regular clock speed
         clock_prescale_set(clock_div_1);
         #endif  // ifdef USE_RAMPING
         #else
         // wait
-        _delay_loop_2(BOGOMIPS*90/100);
+        _delay_loop_2(BOGOMIPS*DELAY_FACTOR/100);
         #endif  // ifdef USE_DYNAMIC_UNDERCLOCKING
 
         // run pending system processes while we wait
diff --git a/spaghetti-monster/fsm-events.h b/spaghetti-monster/fsm-events.h
index 10d3317..9692163 100644
--- a/spaghetti-monster/fsm-events.h
+++ b/spaghetti-monster/fsm-events.h
@@ -54,6 +54,11 @@ uint8_t push_event(uint8_t ev_type);  // only for use by PCINT_inner()
 
 // TODO: Maybe move these to their own file...
 // ... this probably isn't the right place for delays.
+#ifndef DELAY_FACTOR
+// adjust the timing of delays, lower = shorter delays
+// 90 = 90% delay, 10% for other things
+#define DELAY_FACTOR 92
+#endif
 inline void interrupt_nice_delays();
 uint8_t nice_delay_ms(uint16_t ms);
 //uint8_t nice_delay_s();