working simple ec-meter

.gitignore

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+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch
+.pioenvs
+.piolibdeps
+.clang_complete
+.gcc-flags.json

.vscode/extensions.json

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+{
+    // See http://go.microsoft.com/fwlink/?LinkId=827846
+    // for the documentation about the extensions.json format
+    "recommendations": [
+        "platformio.platformio-ide"
+    ],
+    "unwantedRecommendations": [
+        "ms-vscode.cpptools-extension-pack"
+    ]
+}

.vscode/settings.json

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+{
+    "cmake.configureOnOpen": false
+}

README.md

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+# EC-Meter for ESP32
+
+Circuit from: https://publiclab.org/notes/bhickman/05-09-2016/conductivity-and-temperature-meter

include/README

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+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the usual convention is to give header files names that end with `.h'.
+It is most portable to use only letters, digits, dashes, and underscores in
+header file names, and at most one dot.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html

lib/README

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+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into executable file.
+
+The source code of each library should be placed in a an own separate directory
+("lib/your_library_name/[here are source files]").
+
+For example, see a structure of the following two libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional, custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+and a contents of `src/main.c`:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+PlatformIO Library Dependency Finder will find automatically dependent
+libraries scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html

platformio.ini

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+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:esp32doit-devkit-v1]
+platform = espressif32
+board = esp32doit-devkit-v1
+framework = arduino
+
+monitor_speed = 115200

src/main.cpp

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+#include <Arduino.h>
+
+#define EC_PIN_ADC 4
+#define EC_PIN_FREQ 5
+#define EC_PWM_CH 0
+#define EC_RESOLUTION 8
+#define EC_FREQUENCY 5000
+
+#define EC_ARRAY_SIZE 1024
+uint16_t ec_array[EC_ARRAY_SIZE];
+uint16_t ec_array_pos=0;
+unsigned long ec_last_read=0;
+#define EC_READ_INTERVAL 1
+
+unsigned long last_print=0;
+
+float getMean(uint16_t* parray);
+uint16_t getMin(uint16_t *parray);
+uint16_t getMax(uint16_t *parray);
+
+void setup() {
+  Serial.begin(115200);
+  pinMode(EC_PIN_ADC,INPUT);
+
+  ledcSetup(EC_PWM_CH, EC_FREQUENCY, EC_RESOLUTION);
+  ledcAttachPin(EC_PIN_FREQ, EC_PWM_CH);
+  ledcWrite(EC_PWM_CH, 127);
+}
+
+void loop() {
+  unsigned long loopmillis=millis();
+
+  bool flag_print=false;
+
+  if (loopmillis>ec_last_read+EC_READ_INTERVAL) {
+    ec_last_read=loopmillis;
+    ec_array_pos++;
+    flag_print= ec_array_pos==EC_ARRAY_SIZE;
+    ec_array_pos%=EC_ARRAY_SIZE;
+    ec_array[ec_array_pos]=analogRead(EC_PIN_ADC);
+
+    //Serial.print(ec_array[ec_array_pos]); Serial.print(" ");
+  }
+  
+  
+  //if (flag_print) {
+  if (loopmillis>last_print+250) { 
+    last_print=loopmillis;
+    Serial.print(getMean(ec_array),3);
+    Serial.print("\t"); Serial.print(getMax(ec_array) - getMin(ec_array)); 
+    Serial.println();   
+  }
+  
+}
+
+float getMean(uint16_t *parray) {
+  double mean=0;
+  for (uint16_t i=0;i<EC_ARRAY_SIZE;i++) {
+    mean+=parray[i];
+  }
+
+  return mean/EC_ARRAY_SIZE;
+}
+
+
+uint16_t getMin(uint16_t *parray) {
+  uint16_t min=65535;
+  for (uint16_t i=0;i<EC_ARRAY_SIZE;i++) {
+    if (parray[i]<min) {
+      min=parray[i];
+    }
+  }
+
+  return min;
+}
+
+uint16_t getMax(uint16_t *parray) {
+  uint16_t max=0;
+  for (uint16_t i=0;i<EC_ARRAY_SIZE;i++) {
+    if (parray[i]>max) {
+      max=parray[i];
+    }
+  }
+
+  return max;
+}