switched blf-lt1-t1616 from plain PWM to PWM+DSM

(and made DSM interrupt definitions a bit cleaner)

1 files changed, 100 insertions, 43 deletions

diff --git a/hwdef-blf-lt1-t1616.c b/hwdef-blf-lt1-t1616.c
index ea7e6b4..48a401d 100644
--- a/hwdef-blf-lt1-t1616.c
+++ b/hwdef-blf-lt1-t1616.c
@@ -1,6 +1,6 @@
 // Sofirn LT1-t1616 PWM helpers
 // Copyright (C) 2023 SiteRelEnby, Selene ToyKeeper
-// (adapted from emisar-2ch 15/10/2023)
+// SPDX-License-Identifier: GPL-3.0-or-later
 #pragma once
 
 #include "chan-aux.c"
@@ -52,59 +52,125 @@ Channel channels[] = {
 
 
 void set_level_zero() {
-    CH1_PWM = 0;
-    CH2_PWM = 0;
+    // 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;
+    ch2_dsm_lvl = 0;
+    CH1_PWM     = 0;
+    CH2_PWM     = 0;
+    PWM_CNT     = 0;
 }
 
-void set_pwms(PWM_DATATYPE ch1_pwm, PWM_DATATYPE ch2_pwm) {
+void set_hw_levels(PWM_DATATYPE ch1, PWM_DATATYPE ch2) {
+
+    bool was_on = (CH1_PWM>0) || (CH2_PWM>0);
+
+    // set delta-sigma soft levels
+    ch1_dsm_lvl = ch1;
+    ch2_dsm_lvl = ch2;
+
+    // set hardware PWM levels and init dsm loop
+    CH1_PWM = ch1_pwm = ch1 >> 7;
+    CH2_PWM = ch2_pwm = ch2 >> 7;
+
+    // enable timer overflow interrupt so DSM can work
+    DSM_INTCTRL |= DSM_OVF_bm;
+
+    // reset phase when turning on
+    if (! was_on) PWM_CNT = 0;
+
+}
+
+// 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;
     CH2_PWM = ch2_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;
+
+    // repeat for other channels
+
+    ch2_dsm += (ch2_dsm_lvl & 0x007f);
+    ch2_pwm  = (ch2_dsm_lvl >> 7) + (ch2_dsm > 0x7f);
+    ch2_dsm &= 0x7f;
 }
 
+
 void set_level_ch1(uint8_t level) {
-    set_pwms(PWM_GET(pwm1_levels, level), 0);
+    set_hw_levels(PWM_GET(pwm1_levels, level), 0);
 }
 
 void set_level_ch2(uint8_t level) {
-    set_pwms(0, PWM_GET(pwm1_levels, level));
+    set_hw_levels(0, PWM_GET(pwm1_levels, level));
 }
 
 void set_level_both(uint8_t level) {
     PWM_DATATYPE pwm = PWM_GET(pwm1_levels, level);
-    set_pwms(pwm, pwm);
+    set_hw_levels(pwm, pwm);
 }
 
-void set_level_blend(uint8_t level) {
-    PWM_DATATYPE ch1_pwm, ch2_pwm;
+void blend_helper(PWM_DATATYPE *warm, PWM_DATATYPE *cool, uint8_t level) {
     PWM_DATATYPE brightness = PWM_GET(pwm1_levels, level);
-    uint8_t blend           = cfg.channel_mode_args[channel_mode];
+    uint8_t blend;
+    if (channel_mode == CM_AUTO) {
+        blend = 255 * (uint16_t)level / RAMP_SIZE;
+        if (cfg.channel_mode_args[channel_mode] & 0b01000000)
+            blend = 255 - blend;
+    } else {
+        blend = cfg.channel_mode_args[channel_mode];
+    }
 
-    calc_2ch_blend(&ch1_pwm, &ch2_pwm, brightness, PWM_TOP_INIT, blend);
+    calc_2ch_blend(warm, cool, brightness, DSM_TOP, blend);
+}
 
-    set_pwms(ch1_pwm, ch2_pwm);
+void set_level_blend(uint8_t level) {
+    PWM_DATATYPE warm, cool;
+    blend_helper(&warm, &cool, level);
+    set_hw_levels(warm, cool);
 }
 
 void set_level_auto(uint8_t level) {
-    PWM_DATATYPE ch1_pwm, ch2_pwm;
-    PWM_DATATYPE brightness = PWM_GET(pwm1_levels, level);
-    uint8_t blend           = 255 * (uint16_t)level / RAMP_SIZE;
-    if (cfg.channel_mode_args[channel_mode] & 0b01000000)
-        blend = 255 - blend;
-
-    calc_2ch_blend(&ch1_pwm, &ch2_pwm, brightness, PWM_TOP_INIT, blend);
-
-    set_pwms(ch1_pwm, ch2_pwm);
+    PWM_DATATYPE warm, cool;
+    blend_helper(&warm, &cool, level);
+    set_hw_levels(warm, cool);
 }
 
+///// "gradual tick" functions for smooth thermal regulation /////
+// (and other smooth adjustments)
 
 ///// bump each channel toward a target value /////
-bool gradual_adjust(uint16_t ch1_pwm, uint16_t ch2_pwm) {
-    GRADUAL_ADJUST_SIMPLE(ch1_pwm, CH1_PWM);
-    GRADUAL_ADJUST_SIMPLE(ch2_pwm, CH2_PWM);
+bool gradual_adjust(PWM_DATATYPE ch1, PWM_DATATYPE ch2) {
+    // 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;
 
-    // check for completion
-    if ((ch1_pwm == CH1_PWM)
-     && (ch2_pwm == CH2_PWM)) {
+    steps = ch1_dsm_lvl >> shift;
+    for (uint8_t i=0; i<=steps; i++)
+        GRADUAL_ADJUST_SIMPLE(ch1, ch1_dsm_lvl);
+
+    steps = ch2_dsm_lvl  >> shift;
+    for (uint8_t i=0; i<=steps; i++)
+        GRADUAL_ADJUST_SIMPLE(ch2, ch2_dsm_lvl);
+
+    if ((ch1 == ch1_dsm_lvl)
+     && (ch2 == ch2_dsm_lvl )) {
         return true;  // done
     }
     return false;  // not done yet
@@ -126,24 +192,15 @@ bool gradual_tick_both(uint8_t gt) {
 }
 
 bool gradual_tick_blend(uint8_t gt) {
-    PWM_DATATYPE ch1_pwm, ch2_pwm;
-    PWM_DATATYPE brightness = PWM_GET(pwm1_levels, gt);
-    uint8_t blend           = cfg.channel_mode_args[channel_mode];
-
-    calc_2ch_blend(&ch1_pwm, &ch2_pwm, brightness, PWM_TOP_INIT, blend);
-
-    return gradual_adjust(ch1_pwm, ch2_pwm);
+    PWM_DATATYPE warm, cool;
+    blend_helper(&warm, &cool, gt);
+    return gradual_adjust(warm, cool);
 }
 
 bool gradual_tick_auto(uint8_t gt) {
-    PWM_DATATYPE ch1_pwm, ch2_pwm;
-    PWM_DATATYPE brightness = PWM_GET(pwm1_levels, gt);
-    uint8_t blend           = 255 * (uint16_t)gt / RAMP_SIZE;
-    if (cfg.channel_mode_args[channel_mode] & 0b01000000)
-        blend = 255 - blend;
-
-    calc_2ch_blend(&ch1_pwm, &ch2_pwm, brightness, PWM_TOP_INIT, blend);
-
-    return gradual_adjust(ch1_pwm, ch2_pwm);
+    PWM_DATATYPE warm, cool;
+    blend_helper(&warm, &cool, gt);
+    return gradual_adjust(warm, cool);
 }
 
+