From afa8a273ff4610355df467eda0d33be2cdcababa Mon Sep 17 00:00:00 2001
From: kai-morich <mail@kai-morich.de>
Date: Thu, 13 Jan 2022 08:19:50 +0100
Subject: [PATCH] ADCtouch with 10 instead of 8 bit resolution

example with drift compensation
---
 .../examples/Touch_read/Touch_read.ino        | 20 ++++++++++++++++++-
 avr/libraries/ADCTouch/src/ADCTouch.cpp       |  4 ++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/avr/libraries/ADCTouch/examples/Touch_read/Touch_read.ino b/avr/libraries/ADCTouch/examples/Touch_read/Touch_read.ino
index ad5b3501..2ee9ca86 100755
--- a/avr/libraries/ADCTouch/examples/Touch_read/Touch_read.ino
+++ b/avr/libraries/ADCTouch/examples/Touch_read/Touch_read.ino
@@ -29,6 +29,7 @@
 |***********************************************************************/
 
 #include <ADCTouch.h>
+#include <EEPROM.h>
 
 // Sample each touch pin 32 times
 const uint16_t ADCTouch::samples = 32;
@@ -39,11 +40,14 @@ int16_t ref_A3;
 
 // Touch threshold for turning on or off the LEDs
 // Lower is more sensitive
-const uint8_t threshold = 20;
+const uint8_t threshold = 50;
 
 
 void setup()
 {
+  uint8_t cal = EEPROM.read(0);
+  if (cal < 0x80)
+    OSCCAL = cal;
   Serial.begin();
 
   // Reference values to account for the capacitance of the touch pad
@@ -57,6 +61,16 @@ void loop()
   int16_t val_A2 = Touch.read(A2);
   int16_t val_A3 = Touch.read(A3);
 
+  // Drift compensation
+  if(val_A2 > ref_A2)
+    ref_A2++;
+  else
+    ref_A2 = (val_A2 + ref_A2)/2;
+  if(val_A3 > ref_A3)
+    ref_A3++;
+  else
+    ref_A3 = (val_A3 + ref_A3)/2;
+
   // Remove offset
   val_A2 -= ref_A2;
   val_A3 -= ref_A3;
@@ -65,11 +79,15 @@ void loop()
   Serial.print(val_A2 > threshold); // Send (boolean) pressed or not pressed
   Serial.print(F(", A2 touch value: "));
   Serial.print(val_A2);
+  Serial.print(F(", A2 ref value: "));
+  Serial.print(ref_A2);
 
   Serial.print(F("\tA3 touch bool: "));
   Serial.print(val_A3 > threshold); // Send (boolean) pressed or not pressed
   Serial.print(F(", A3 touch value: "));
   Serial.print(val_A3);
+  Serial.print(F(", A3 ref value: "));
+  Serial.print(ref_A3);
   Serial.print('\n');
   delay(100);
 }
diff --git a/avr/libraries/ADCTouch/src/ADCTouch.cpp b/avr/libraries/ADCTouch/src/ADCTouch.cpp
index 4ae246f9..906fa521 100755
--- a/avr/libraries/ADCTouch/src/ADCTouch.cpp
+++ b/avr/libraries/ADCTouch/src/ADCTouch.cpp
@@ -25,7 +25,7 @@ int16_t ADCTouch::read(const analog_pin_t adc_channel)
   uint8_t digitalPin = pgm_read_byte(analog_pin_to_digital_pin + adc_channel);
   do
   {
-    ADMUX = (1 << ADLAR) | adc_channel; // Select ADC channel
+    ADMUX = adc_channel;                // Select ADC channel
     DDRB |= (1 << digitalPin);          // Discharge touchpad
 
     ADCSRA |= (1 << ADEN);              // Enable ADC & discharge S/H cap
@@ -42,7 +42,7 @@ int16_t ADCTouch::read(const analog_pin_t adc_channel)
 
     ADCSRA |= (1 << ADSC);              // Start ADC conversion
     while (bit_is_set(ADCSRA, ADSC));   // Wait for conversion to complete
-    level += ADCH;
+    level += ADCW;
     ADCSRA = 0;                         // ADC off
   }
   while(--samples_left);