1. GY-291
This module has all pins on one side, it is very sensitive ( more then others) and looks like is not calibrated at all. Price is 2.27 USD with free shipping.
2. ADXL345 module
Pins are distributed on both sides and has two pins for power on if you want to use it with 5V and one for 3.3V so it can be used with arduino or esp8266. It is well calibrated and well build. It costs more then the GY-291 with few cents but for my projects is very good. At this time the price is 2.72 USD with free shipping.
3. SparkFun
Most expensive one 17.95 USD shipping not included is well built, and calibrated. Of course for its price you can buy at least 6 modules like this one.
All the modules have the advantages of the ADXL345 chip like tap, double tap, free fall, two interrupts, range up to 16G
At the end top is 2, 3, 1.
Some code for ESP8266 to play with.
/* ADXL345
* i2c bus SDA = GPIO0; SCL = GPIO2
*
* Just a little test message. Go to http://192.168.4.1 in a web browser
* connected to this access point to see it.
* USER: admin PASSWOR: admin
*/
#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
//ADXL345
#include <Wire.h>
/* Set these to your desired credentials. */
const char *ssid = "ESPap";
const char *password = "12345678";
ESP8266WebServer server(80);
#define DEBUG true
#define Serial if(DEBUG)Serial
#define DEVICE (0x53) // Device address as specified in data sheet
float last_value = 0;
float prelast_value = 0;
int show_count = 0;
int trigger_count = 0;
float trigger_value = -5; //DEFAULT VALUE ???
float current_value = 0;
#define ADXL345_MG2G_MULTIPLIER (0.004)
#define SENSORS_GRAVITY_STANDARD (SENSORS_GRAVITY_EARTH)
#define SENSORS_GRAVITY_EARTH (9.80665F) /**< Earth's gravity in m/s^2 */
byte _buff[6];
char POWER_CTL = 0x2D; //Power Control Register
char DATA_FORMAT = 0x31;
char DATAX0 = 0x32; //X-Axis Data 0
char DATAX1 = 0x33; //X-Axis Data 1
//char DATAY0 = 0x34; //Y-Axis Data 0
//char DATAY1 = 0x35; //Y-Axis Data 1
//char DATAZ0 = 0x36; //Z-Axis Data 0
//char DATAZ1 = 0x37; //Z-Axis Data 1
float max_x=0;
float min_x=0;
float cal_x=0;
float x = 0;
//Check if header is present and correct
bool is_authentified(){
Serial.println("Enter is_authentified");
if (server.hasHeader("Cookie")){
Serial.print("Found cookie: ");
String cookie = server.header("Cookie");
Serial.println(cookie);
if (cookie.indexOf("ESPSESSIONID=1") != -1) {
Serial.println("Authentification Successful");
return true;
}
}
Serial.println("Authentification Failed");
return false;
}
//root page can be accessed only if authentification is ok
void handleRoot(){
Serial.println("Enter handleRoot");
String header;
if (!is_authentified())
{
String header = "HTTP/1.1 301 OK\r\nLocation: /login\r\nCache-Control: no-cache\r\n\r\n";
server.sendContent(header);
return;
}
if (server.hasArg("RESET"))
{
Serial.println("Reset max and min values");
min_x=0;
max_x=0;
String content = "<html><body><h2>ADXL Demo</h2>";
content += " <a href=\"/login\">reset</a><BR><BR>";
server.send(200, "text/html", content);
}
String content = "<html><body><h2>ADXL demo</h2>";
//<H2>hello, you successfully connected to esp8266!</H2><br>";
if (server.hasHeader("User-Agent"))
{
//content += "the user agent used is : " + server.header("User-Agent") + "<br><br>";
content += "x :" + String((int)current_value ) + " Corr(x):" + String((float)current_value - cal_x ) + " min_x:" + String((float)min_x) + " max_x:" + String((float)max_x) + "<br><br>";
content += "Trigger value:" + String((float)trigger_value) + " trigger count:" + String(trigger_count) + "<br><br>";
}
content += " <a href=\"/login?DISCONNECT=YES\">disconnect</a><BR><BR>";
content += " <a href=\"/?RESET=YES\">Reset min and max values</a><br><br>";
content += " <a href=\"/settings\">Settings</a>";
//last line
content += " </body></html>";
server.send(200, "text/html", content);
}
void handleSettings()
{
//reading
if (server.hasArg("TRIGGER"))
{
trigger_value = server.arg("TRIGGER").toInt();
return;
}
//setting
String msg = " <br><br> <a href=\"/ \">Home</a>";
String content = "<html><body><form action='/settings' method='POST'><br>";
content += "Value:<input type='number' name='TRIGGER' min='-500' max='500' placeholder='trigger value'><br>";
content += "<input type='submit' name='SUBMIT' value='Submit'></form>" + msg + "<br>";
server.send(200, "text/html", content);
}
//login page, also called for disconnect
void handleLogin(){
String msg;
if (server.hasHeader("Cookie")){
Serial.print("Found cookie: ");
String cookie = server.header("Cookie");
Serial.println(cookie);
}
if (server.hasArg("DISCONNECT")){
Serial.println("Disconnection");
String header = "HTTP/1.1 301 OK\r\nSet-Cookie: ESPSESSIONID=0\r\nLocation: /login\r\nCache-Control: no-cache\r\n\r\n";
server.sendContent(header);
return;
}
if (server.hasArg("USERNAME") && server.hasArg("PASSWORD")){
if (server.arg("USERNAME") == "admin" && server.arg("PASSWORD") == "admin" ){
String header = "HTTP/1.1 301 OK\r\nSet-Cookie: ESPSESSIONID=1\r\nLocation: /\r\nCache-Control: no-cache\r\n\r\n";
server.sendContent(header);
Serial.println("Log in Successful");
return;
}
msg = "Wrong username/password! try again.";
Serial.println("Log in Failed");
}
String content = "<html><body><form action='/login' method='POST'>To log in, please use : admin/admin<br>";
content += "User:<input type='text' name='USERNAME' placeholder='user name'><br>";
content += "Password:<input type='password' name='PASSWORD' placeholder='password'><br>";
content += "<input type='submit' name='SUBMIT' value='Submit'></form>" + msg + "<br>";
content += "You also can go <a href='/inline'>here</a></body></html>";
server.send(200, "text/html", content);
}
//no need authentification
void handleNotFound()
{
String message = "File Not Found\n\n";
message += "URI: ";
message += server.uri();
message += "\nMethod: ";
message += (server.method() == HTTP_GET)?"GET":"POST";
message += "\nArguments: ";
message += server.args();
message += "\n";
for (uint8_t i=0; i<server.args(); i++){
message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
}
server.send(404, "text/plain", message);
}
float readAccel()
{
Serial.print("readAccel");
uint8_t howManyBytesToRead = 6; //6 for all axes
readFrom( DATAX0, howManyBytesToRead, _buff); //read the acceleration data from the ADXL345
short x =0;
x = (((short)_buff[1]) << 8) | _buff[0];
//short y = (((short)_buff[3]) << 8) | _buff[2];
//short z = (((short)_buff[5]) << 8) | _buff[4];
Serial.println(x * ADXL345_MG2G_MULTIPLIER * SENSORS_GRAVITY_STANDARD);
return x * ADXL345_MG2G_MULTIPLIER * SENSORS_GRAVITY_STANDARD;
//x = x + cal_x;
//Serial.print("x: ");
//Serial.print( x*2./512 );
//Serial.print(" y: ");
//Serial.print( y*2./512 );
//Serial.print(" z: ");
//Serial.print( z*2./512 );
//Serial.print("X: "); Serial.print( x);
//Serial.println( sqrtf(x*x+y*y+z*z)*2./512 );
//getX() = read16(ADXL345_REG_DATAX0);
//x = getX() * ADXL345_MG2G_MULTIPLIER * SENSORS_GRAVITY_STANDARD;
}
void writeTo(byte address, byte val)
{
Wire.beginTransmission(DEVICE); // start transmission to device
Wire.write(address); // send register address
Wire.write(val); // send value to write
Wire.endTransmission(); // end transmission
}
// Reads num bytes starting from address register on device in to _buff array
void readFrom(byte address, int num, byte _buff[])
{
Wire.beginTransmission(DEVICE); // start transmission to device
Wire.write(address); // sends address to read from
Wire.endTransmission(); // end transmission
Wire.beginTransmission(DEVICE); // start transmission to device
Wire.requestFrom(DEVICE, num); // request 6 bytes from device
int i = 0;
while(Wire.available()) // device may send less than requested (abnormal)
{
_buff[i] = Wire.read(); // receive a byte
i++;
}
Wire.endTransmission(); // end transmission
}
void setup() {
delay(1000);
Serial.begin(115200);
Serial.println();
Serial.print("Configuring access point...");
/* You can remove the password parameter if you want the AP to be open. */
WiFi.softAP(ssid, password);
IPAddress myIP = WiFi.softAPIP();
Serial.print("AP IP address: ");
Serial.println(myIP);
server.on("/", handleRoot);
server.on("/login", handleLogin);
server.on("/settings", handleSettings);
server.on("/inline", [](){
server.send(200, "text/plain", "this works without need of authentification");
});
server.onNotFound(handleNotFound);
//here the list of headers to be recorded
const char * headerkeys[] = {"User-Agent","Cookie"} ;
size_t headerkeyssize = sizeof(headerkeys)/sizeof(char*);
//ask server to track these headers
server.collectHeaders(headerkeys, headerkeyssize );
server.begin();
Serial.println("HTTP server started");
//ADXL345
// i2c bus SDA = GPIO0; SCL = GPIO2
Wire.begin(0,2);
// Put the ADXL345 into +/- 2G range by writing the value 0x01 to the DATA_FORMAT register.
// FYI: 0x00 = 2G, 0x01 = 4G, 0x02 = 8G, 0x03 = 16G
writeTo(DATA_FORMAT, 0x00);
// Put the ADXL345 into Measurement Mode by writing 0x08 to the POWER_CTL register.
writeTo(POWER_CTL, 0x08);
int i =0;
for(i=0; i<11; i++)
{
//uint8_t howManyBytesToRead = 6;
//readFrom( DATAX0, howManyBytesToRead, _buff);
float calib_x ;//= (((short)_buff[1]) << 8) | _buff[0];
calib_x = readAccel();
//if(i==0)
// cal_x = x;
if(i>0)
cal_x = cal_x + calib_x;
Serial.println(calib_x);
delay(100);
}
cal_x = cal_x/10;
Serial.print("cal_x: ");Serial.println(cal_x);
}
void loop() {
server.handleClient();
current_value = readAccel(); // read ONLY x, for the y and x modify the readAccel function
if((current_value - cal_x) > max_x)
max_x = current_value - cal_x;
if((current_value - cal_x) < min_x)
min_x = current_value - cal_x;
Serial.print("x: ");Serial.print(current_value); Serial.print(" x(corrected): ");Serial.print(current_value - cal_x);
Serial.print(" Min:" );Serial.print(min_x); Serial.print(" Max:" ); Serial.println(max_x);
Serial.print("Trigger value:"); Serial.print(trigger_value); Serial.print(" Count:"); Serial.println(trigger_count);
delay(100); // only read every 100ms
}
For ESP32 info and projects see my ESP32 blog.
