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LPC1768

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LPC1768 and MLX90614 infrared thermometer

by shedboy71
written by shedboy71

The MLX90614 is a non-contact infrared thermometer with a measurement range from -70 to +380 degree Celsius. Just connect the four leads to your MBed supported device and you will have a accurate thermometer with a resolution of 0.01 and a accuracy of 0.5 degrees, or for that matter you can use any microcontroller that can communicate with it through it’s I2C interface.

Being an I2C device you simply need to connect to the SDA, SCL and choose a suitable GND and Vin. I used 3.3v to be safe, although the breakout states 3 to 5v.

This version I chose comes with a breakout board with all of the components needed for operation. Here is a picture of that breakout board

gy-906-2-300x200

 

Features:
Small size, low cost
Mounted on a breakout board with two types of pins
10k Pull up resistors for the I2C interface with optional solder jumpers
Factory calibrated in wide temperature range:
-40 … + 125 ° C for sensor temperature and
-70 … + 380 ° C for object temperature.
High accuracy of 0.5 ° C over wide temperaturerange (0 … + 50 ° C for both Ta and To) High (medical) accuracy calibration
Measurement resolution of 0.02 ° C
Single and dual zone versions
SMBus compatible digital interface
Customizable PWM output for continuous reading
Sleep mode for reduced power consumption

 

Layout and Connection

I used the following connection from the module above to my Wemos Mini

LPC1768 Connection Module Connection
VOUT VIN
Gnd Gnd
SDA – Pin 28 SDA
SCL – Pin 27 SCL

Here is a layout

mbed1768-and-mlx90614_bb

 

 

Code

You need to import the following library  and code

[codesyntax lang=”cpp”]

#include "mbed.h"
#include "mlx90614.h"


I2C i2c(p28,p27); //sda,scl
Serial pc(USBTX,USBRX); //serial usb config

MLX90614 IR_thermometer(&i2c);


float temp; //temperature in degrees C

int main() 
{ 
 pc.baud(115200);
 while (1) 
 {
 if (IR_thermometer.getTemp(&temp)) 
 {
 printf("Temperature is %5.1F degrees C\r\n",temp);
 }
 //wait for device to produce next temperature reading
 wait(1.0);
 }
}

[/codesyntax]

Using a terminal program you will hopefully see the following

Temperature is 24.6 degrees C
Temperature is 24.6 degrees C
Temperature is 24.7 degrees C
Temperature is 24.6 degrees C
Temperature is 24.6 degrees C
Temperature is 24.0 degrees C
Temperature is 23.6 degrees C
Temperature is 25.8 degrees C
Temperature is 27.6 degrees C
Temperature is 30.4 degrees C
Temperature is 48.1 degrees C
Temperature is 51.9 degrees C
Temperature is 44.0 degrees C
Temperature is 34.6 degrees C
Temperature is 32.6 degrees C

 

Links

Here is a link to the datasheet and also the breakout I purchased, come in at about $9 a piece.

MLX90614 datasheet
MLX90614 Contactless IR Infrared Thermometer Sensor Module IIC for Arduino

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MBed

MBed LPC1768 and ADXL345 GY-291 example

by shedboy71
written by shedboy71
The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16g. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface.

The ADXL345 is well suited for mobile device applications. It measures the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock. Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°.

Several special sensing functions are provided. Activity and inactivity sensing detect the presence or lack of motion and if the acceleration on any axis exceeds a user-set level. Tap sensing detects single and double taps. Free-fall sensing detects if the device is falling. These functions can be mapped to one of two interrupt output pins. An integrated, patent pending 32-level first in, first out (FIFO) buffer can be used to store data to minimize host processor intervention.

adxl345-module

Connection

I used the following connection from the module above to my MBED 1768

MBED Connection Module Connection
3v3 – VOUT VCC
Gnd Gnd
SDA – Pin 28 SDA
SCL – Pin 27 SCL

 

This is a layout showing the connection

mbed1768-and-adxl345_bb

Code

This needs the following example – https://developer.mbed.org/users/peterswanson87/code/ADXL345_I2C/ – Add this to the MBed compiler

Here is the code

[codesyntax lang=”cpp”]

#include "ADXL345_I2C.h"

 ADXL345_I2C accelerometer(p28, p27);
 Serial pc(USBTX, USBRX);

 int main() {
 pc.baud(115200);
 int readings[3] = {0, 0, 0};
 
 pc.printf("Starting ADXL345 test...\n");
 wait(.001);
 pc.printf("Device ID is: 0x%02x\n", accelerometer.getDeviceID());
 wait(.001);
 
 // These are here to test whether any of the initialization fails. It will print the failure
 if (accelerometer.setPowerControl(0x00)){
 pc.printf("didn't intitialize power control\n"); 
 return 0; }
 //Full resolution, +/-16g, 4mg/LSB.
 wait(.001);
 
 if(accelerometer.setDataFormatControl(0x0B)){
 pc.printf("didn't set data format\n");
 return 0; }
 wait(.001);
 
 //3.2kHz data rate.
 if(accelerometer.setDataRate(ADXL345_3200HZ)){
 pc.printf("didn't set data rate\n");
 return 0; }
 wait(.001);
 
 //Measurement mode.
 
 if(accelerometer.setPowerControl(MeasurementMode)) {
 pc.printf("didn't set the power control to measurement\n"); 
 return 0; } 
 
 while (1) {
 
 wait(0.1);
 
 accelerometer.getOutput(readings);
 

 pc.printf("%i, %i, %i\n", (int16_t)readings[0], (int16_t)readings[1], (int16_t)readings[2]);
 }
 
 }

[/codesyntax]

 

Links
GY-291 ADXL345 3-Axis Digital Gravity Sensor Acceleration Module IIC/SPI transmission

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