Hi all,
I would like to show you my first project with an ESP32. This year, I have built a garden shed with a small greenhouse attached to it:
I thought, it would be nice to somehow see how warm or cold it gets over the year. As I can get Ruuvi tags for free from work, I was looking for a convenient way to read their data without having to walk out with my phone and then learned about ESP32 microcontrollers.
Here is the finished device in it's place:
The hardware is wired as follows - I am using a 5 Ah LiPo battery that I also got from company trash, which I can charge via a TP4056 charging module/USB C. The ESP32 itself is powered by a Pololu 3.3V voltage regulator:
I can check on the battery level by measuring the battery voltage on an analog IN over a voltage divider on the ESP32.
The wiring is a bit bonkers, but it works:
There are two Ruuvi tags - one inside and one just outside the greenhouse. The ESP32 is scanning BLE until both Ruuvi's data is received, then sends the raw Hex strings over my WiFi to a google sheet. Then it deep sleeps for 15 minutes. Here is the code:
#include <HTTPClient.h> // version 2.2.0
#include <WiFi.h>
#include <NimBLEDevice.h> // version 1.4.3
#include <esp_sleep.h>
#define uS_TO_S_FACTOR 1000000 // Conversion factor for micro seconds to seconds
#define TIME_TO_SLEEP 890 // Time ESP32 will go to sleep (in seconds) - 15 minutes minus the average runtime.
HTTPClient http; // Declare HTTPClient object globally
BLEScan* pBLEScan;
const int analogPin = 32; // ADC pin
int adcValue;
const char* ssid = "SSID";
const char* password = "PASSWORD";
String googleURL = "https://script.google.com/macros/s/AKfycbxxxxxxxMIfZjTdIYfxw46fAEJ5PWxxxxxxx/exec?";
String googleURL_with_parameters = "";
const char* MAC_inside_sensor = "E8:B9:9A:E5:54:BE";
const char* MAC_outside_sensor = "CE:6A:CC:E0:7E:1E";
char HEX_inside_sensor[128] = "";
char HEX_outside_sensor[128] = "";
char macAddress[128] = "";
int BLEscanTime = 15; // In seconds. Long scan time will be stopped once both sensors are found.
// Function to convert a string to uppercase. Used for MAC Addresses and Data of Ruuvi sensors.
void toUpperCase(char* str) {
for (int i = 0; str[i]; i++) {
str[i] = toupper(str[i]);
}
}
void connectToWiFi() {
delay(1000); //before setting up WiFi
WiFi.disconnect();
delay(1000);
WiFi.begin(ssid, password);
unsigned long startAttemptTime = millis();
while (WiFi.status() != WL_CONNECTED && millis() - startAttemptTime < 10000) { // 10 seconds timeout
delay(1000);
Serial.println("Connecting to WiFi...");
}
if (WiFi.status() == WL_CONNECTED) {
Serial.println("Connected to WiFi");
} else {
Serial.println("Failed to connect to WiFi. Reconnecting...");
// Retry mechanism
for (int i = 0; i < 5; i++) {
WiFi.begin(ssid, password);
delay(2000);
if (WiFi.status() == WL_CONNECTED) {
Serial.println("Connected to WiFi");
break;
}
}
if (WiFi.status() != WL_CONNECTED) {
Serial.println("Failed to connect to WiFi after multiple attempts.");
}
}
}
class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
void onResult(BLEAdvertisedDevice* advertisedDevice) {
strncpy(macAddress, advertisedDevice->getAddress().toString().c_str(), sizeof(macAddress) - 1);
macAddress[sizeof(macAddress) - 1] = '\0'; // Ensure null-termination
toUpperCase(macAddress);
if (strcmp(MAC_inside_sensor, macAddress) == 0 && HEX_inside_sensor[0] == '\0') {
char* hexData = BLEUtils::buildHexData(nullptr, (uint8_t*)advertisedDevice->getManufacturerData().c_str(), advertisedDevice->getManufacturerData().length());
snprintf(HEX_inside_sensor, sizeof(HEX_inside_sensor), "%s", hexData);
free(hexData); // Free the allocated memory
toUpperCase(HEX_inside_sensor);
Serial.println("Found inside sensor: " + String(macAddress));
}
if (strcmp(MAC_outside_sensor, macAddress) == 0 && HEX_outside_sensor[0] == '\0') {
char* hexData = BLEUtils::buildHexData(nullptr, (uint8_t*)advertisedDevice->getManufacturerData().c_str(), advertisedDevice->getManufacturerData().length());
snprintf(HEX_outside_sensor, sizeof(HEX_outside_sensor), "%s", hexData);
free(hexData); // Free the allocated memory
toUpperCase(HEX_outside_sensor);
Serial.println("Found outside sensor: " + String(macAddress));
}
if (HEX_inside_sensor[0] != '\0' && HEX_outside_sensor[0] != '\0') {
Serial.println("Found both sensors");
pBLEScan->stop();
Serial.println("STOPPING SCAN");
}
}
};
void transmitData() {
if (HEX_inside_sensor[0] != '\0' && HEX_outside_sensor[0] != '\0'){
googleURL_with_parameters = googleURL + "&HEXin=" + HEX_inside_sensor + "&HEXout=" + HEX_outside_sensor + "&SRCPOW=" + adcValue;
Serial.println("URL: " + googleURL_with_parameters);
Serial.println("Data transmission starting... Heap memory: " + String(esp_get_free_heap_size()) + " bytes");
if (WiFi.status() == WL_CONNECTED) {
http.begin(googleURL_with_parameters);
int httpResponseCode = http.GET();
if (httpResponseCode > 0) {
String response = http.getString();
Serial.println(httpResponseCode);
//Serial.println(response);
} else {
Serial.print("Error on HTTP request: ");
Serial.println(httpResponseCode);
connectToWiFi();
http.end();
http.begin(googleURL_with_parameters);// try again if first try did not succeed.
}
http.end();
} else {
Serial.println("Error in WiFi connection. Re-initializing WiFi...");
connectToWiFi();
}
HEX_inside_sensor[0] = '\0';
HEX_outside_sensor[0] = '\0';
Serial.println("Hex values resetted.");
Serial.println("Data transmission done. Heap memory: " + String(esp_get_free_heap_size()) + " bytes");
}
}
void setup() {
Serial.begin(115200);
delay(2000);
// Configure wake up source
esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);
Serial.println("Setup ESP32 to sleep for every " + String(TIME_TO_SLEEP) + " Seconds");
//read the analog pin for the battery voltage
adcValue = analogRead(analogPin);
Serial.println("ADC Value for PIN32: " + String(adcValue));
//BLE
BLEDevice::init("");
pBLEScan = BLEDevice::getScan(); // create new scan
pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
pBLEScan->setActiveScan(true); // active scan uses more power, but gets results faster
pBLEScan->setInterval(100);
pBLEScan->setWindow(99); // less or equal setInterval value
connectToWiFi();
http.setTimeout(20000); // Set timeout to 20 seconds
while (HEX_inside_sensor[0] == '\0' || HEX_outside_sensor[0] == '\0'){
Serial.println("STARTING NEW SCAN");
BLEScanResults foundDevices = pBLEScan->start(BLEscanTime, false);
pBLEScan->clearResults(); // delete results from BLEScan buffer to release memory
delay(1000);
}
transmitData();
Serial.println("Going to sleep now");
esp_deep_sleep_start();
}
void loop() {
//not needed here
}
The raw Hex values get converted and processed by a google apps script:
function doGet(e) {
var dataSheetName = 'data';
var sheet = SpreadsheetApp.openById('1kZG9-848u-M0Ixxxxx').getSheetByName(dataSheetName);
// Extract and log each parameter
var in_HEX = e.parameter.HEXin || "IN not found";
var out_HEX = e.parameter.HEXout || "OUT not found";
var batteryRaw = e.parameter.SRCPOW || "BATTERY not found";
// Append the data to the sheet
var in_data = decodeRuuvi(in_HEX);
var out_data = decodeRuuvi(out_HEX);
var batteryVoltage = convertPower(batteryRaw);
// Insert a new row at position 4
sheet.insertRowBefore(4);
sheet.getRange(4, 1, 1, 12).setValues([[new Date(), in_data.temp, in_data.hum, in_data.pressure, in_data.txpower, in_data.voltage,
out_data.temp, out_data.hum, out_data.pressure, out_data.txpower, out_data.voltage, batteryVoltage]]);
return ContentService.createTextOutput('Success');
}
function convertPower(rawValue){
var correctionFactor = 1.3628; //derived from the voltage divider with R1=32,6k and R2=11,86k
var convertedValue = 3.3 * rawValue / 4095.0 * correctionFactor;
return convertedValue;
}
function decodeRuuvi(hex_data) {
var data = {}; // Create an object to hold the decoded data
if (hex_data.substring(4, 6) == "05") { // Check if the data format is supported
data.temp = decodeTemperature(hex_data.substring(6, 10)); // Decode temperature
data.hum = hexadecimalToDecimal(hex_data.substring(10, 14)) * 0.0025; // Decode humidity
data.pressure = hexadecimalToDecimal(hex_data.substring(14, 18)) * 1 + 50000; // Decode pressure
data.ax = hexadecimalToDecimal(hex_data.substring(18, 22)); // Decode acceleration in X-axis
data.ay = hexadecimalToDecimal(hex_data.substring(22, 26)); // Decode acceleration in Y-axis
data.az = hexadecimalToDecimal(hex_data.substring(26, 30)); // Decode acceleration in Z-axis
if (data.ax > 0xF000) { // Adjust for negative values in X-axis
data.ax = data.ax - (1 << 16);
}
if (data.ay > 0xF000) { // Adjust for negative values in Y-axis
data.ay = data.ay - (1 << 16);
}
if (data.az > 0xF000) { // Adjust for negative values in Z-axis
data.az = data.az - (1 << 16);
}
var voltage_power = hexadecimalToDecimal(hex_data.substring(30, 34)); // Decode voltage and TX power
var voltage_mask = 0b1111111111100000; // Mask for the first 11 bits (voltage)
var voltage_bits = voltage_power & voltage_mask; // Apply mask to get voltage bits
voltage_bits = voltage_bits >> 5; // Align the bits after masking
data.voltage = voltage_bits + 1600; // Voltage in millivolts
data.voltage = data.voltage / 1000.0; // Convert to volts
var txpower_mask = 0b0000000000011111; // Mask for the last 5 bits (TX power)
data.txpower = (voltage_power & txpower_mask) - 40; // TX power in dBm
} else {
Logger.log("Error: Unsupported data format"); // Log error if data format is unsupported
}
return data; // Return the decoded data
}
function decodeTemperature(hexVal) {
var temp = hexadecimalToDecimal(hexVal);
if (temp > 0x7FFF) { // Check if the MSB is set (indicating a negative value)
temp = temp - (1 << 16); // Convert from two's complement to negative decimal
}
return temp * 0.005; // Apply the scaling factor
}
// Function to convert hexadecimal string to decimal
function hexadecimalToDecimal(hexVal) {
var len = hexVal.length; // Get the length of the hexadecimal string
var base = 1; // Initialize base value to 1 (16^0)
var dec_val = 0; // Initialize decimal value to 0
for (var i = len - 1; i >= 0; i--) { // Loop through each character of the hexadecimal string
var char = hexVal[i];
if (char >= '0' && char <= '9') { // If the character is a digit
dec_val += (char.charCodeAt(0) - 48) * base; // Convert to decimal and add to dec_val
base = base * 16; // Update base to next power of 16
} else if (char >= 'A' && char <= 'F') { // If the character is a letter (A-F)
dec_val += (char.charCodeAt(0) - 55) * base; // Convert to decimal and add to dec_val
base = base * 16; // Update base to next power of 16
}
}
return dec_val; // Return the decimal value
}
function lowVoltageWarning(){
var dataSheetName = 'data';
var sheet = SpreadsheetApp.openById('1kZG9-848u-M0I6bekcFO8ZPDLU0Ta8Cr_sLxEPXinOI').getSheetByName(dataSheetName);
var cellValue = sheet.getRange("L4").getValue();
if (cellValue < 3.5) {
var emailAddress = "x@gmail.com"; // Replace with your email address
var subject = "AMBIENT CONTROL Alert: Battery Voltage Below 3.5 V";
var message = "The value in cell L4 on the 'data' sheet is below 3.5.";
MailApp.sendEmail(emailAddress, subject, message);
}
}
Then I am displaying the humidity and temperature for both in- and outside on a dashboard, day- and week-charts as well as a battery level chart:
I am happy how this all turned out for doing all that stuff for the first time. Here I would like give a big T H A N K Y O U ! ! ! to @kmin and @kenb4 for helping me to get this working!
regards
Jochen
