From 1696e1f04d25a25e33f7d048d0ea9696176c0db4 Mon Sep 17 00:00:00 2001
From: Fisch <interfisch@gmx.net>
Date: Sat, 24 Sep 2022 16:41:47 +0200
Subject: [PATCH] add volume log fix for linear potentiometer

---
 .../mixercontroller_w5100_pio/src/main.cpp    | 42 ++++++++++++++++---
 1 file changed, 36 insertions(+), 6 deletions(-)

diff --git a/controller/mixercontroller_w5100_pio/src/main.cpp b/controller/mixercontroller_w5100_pio/src/main.cpp
index 05d5bb7..99aa4b6 100644
--- a/controller/mixercontroller_w5100_pio/src/main.cpp
+++ b/controller/mixercontroller_w5100_pio/src/main.cpp
@@ -36,6 +36,9 @@ void changeRelaisByNumberTopic(uint8_t pn, String pTopicPrefix, uint8_t pindex,
 void setRelaisByNumber(uint8_t pn, String pTopicPrefix, uint8_t pnumber, bool pstate, void (*psetXChannel) (uint8_t, boolean));
 float getSetVolume();
 uint8_t getIndex(uint8_t pn, String pTopic);
+float mapPotiToVolume(int p);
+int mapVolumeToPoti(float v);
+float mapfloat(float x, float in_min, float in_max, float out_min, float out_max);
 
 #define LEDPIN 9  //PB1 = D9 = Pin15
 #define NUMLED 9
@@ -97,7 +100,7 @@ uint16_t srbits=0;
 
 #include <Encoder.h>
 Encoder volEnc(PIN_ENCA,PIN_ENCB);
-float encoderMultiplier=4.0;
+float encoderMultiplier=0.4;
 int volEncVel=0;
 
 //Servo stuff
@@ -115,6 +118,7 @@ int _motormove;
 #define POTIFILTER 0.5 //0 to 1. 1 means old value stays forever
 #define MAX_MOTOR_PWM 255 //0 to 255. Maximum pwm to output
 
+float poti_volume_set=0; //set value as volume (poti is linear, volume is log). [0.0, 100.0]
 int poti_set; //set value, initial value will be read from poti
 int poti_read=0; //read value from poti
 boolean poti_reachedposition=true; //set to true if position reached. after that stop turning
@@ -253,6 +257,7 @@ void setup() {
 
 
   poti_set=analogRead(PIN_POT);
+  poti_volume_set=round(mapPotiToVolume(poti_set));
 
   #ifdef DEBUG
   Serial.println("Ready");
@@ -402,7 +407,9 @@ void loop() {
   if (volEncVel!=0){ //knob moved
     switch(menu_mode) {
       case 0: //volume
-        poti_set+=volEncVel*encoderMultiplier; //change poti set value
+        poti_volume_set+=volEncVel*encoderMultiplier; //change poti set value
+        poti_volume_set=constrain(poti_volume_set, 0.0,100.0);
+        poti_set=mapVolumeToPoti(poti_volume_set);
         poti_set=constrain(poti_set, POT_MIN,POT_MAX);
         poti_reachedposition=false;
         flag_publishCurrentSetVolume=true;
@@ -640,9 +647,9 @@ void callback(char* topic, byte* payload, unsigned int length) {
 
   if (String(topic).equals("audiomixer/volume/set")){
     float _floatvalue = spayload.toFloat();
-    _floatvalue=constrain(_floatvalue,0.0,100.0);
+    poti_volume_set=constrain(_floatvalue,0.0,100.0);  //set new poti position
     
-    poti_set=constrain(map(_floatvalue,0.0,100.0,POT_MIN,POT_MAX),POT_MIN,POT_MAX); //set new poti position
+    poti_set=mapVolumeToPoti(poti_volume_set);
     poti_reachedposition=false; //aim for new position
 
     publishCurrentSetVolume();
@@ -818,5 +825,28 @@ void setRelaisByNumber(uint8_t pn, String pTopicPrefix, uint8_t pnumber, bool ps
 
 
 float getSetVolume() {
-  return map(poti_set,POT_MIN,POT_MAX, 0.0,100.0); //get percentage from set poti value
-}
\ No newline at end of file
+  //return map(poti_volume_set,POT_MIN,POT_MAX, 0.0,100.0); //get percentage from set poti value
+  return poti_volume_set;
+}
+
+float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
+{
+  return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+}
+
+#define STEEPNESS 10.0  //has to be a float!
+int mapVolumeToPoti(float v) {
+  v=v/100.0;
+  //volume is [0.,100.]
+  //poti is [POTI_MIN,POTI_MAX]
+  float pout=(pow(STEEPNESS,v)-1)/(STEEPNESS-1);
+  return mapfloat(pout,0.0,1.0, POT_MIN, POT_MAX);
+}
+
+float mapPotiToVolume(int p) {
+  //volume is [0.,100.]
+  //poti is [POTI_MIN,POTI_MAX]
+  float pmapped=mapfloat((float)p,POT_MIN,POT_MAX,0.0,1.0);
+  return (log((STEEPNESS-1)*( pmapped+(1/(STEEPNESS-1)) ))/log(STEEPNESS))*100.0;
+}
+