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Espruino

Espruino and DS18B20 temperature sensor

by shedboy71 3rd October 2016

written by shedboy71

The DS18B20 is a temperature sensor that can be used in various simple projects. This part uses the 1 wire bus and you can connect multiple sensors up to your Espruino.

The part is also relatively low cost and only requires an additional 4k7 pull up resistor. In the example below we shall make a basic example that reads the temperature and outputs via serial and can be verified using the console window in Espruino Web IDE.

Lets look at the parts list

Parts List

Label	Part Type
DS1	DS18B20 1-Wire Temperature Sensor
Part1	Espruino
R1	4.7k Ω Resistor

Layout

As always be careful not to get the connections incorrect, you can refer to the pinout for the device below to help . The DS18B20 can be powered by between 3.0V and 5.5V so you can simply connect its GND pin to 0V and the VDD pin to +3v3 from the Espruino

ds18b20-pinout

Here is the connection diagram showing how to connect your Espruino to the resistor and sensor.

espruino-and-ds18b20_bb

Code

[codesyntax lang=”javascript”]

require("DS18B20");

var ow = new OneWire(B3);
var sensor = require("DS18B20").connect(ow);
setInterval(function() {
  sensor.getTemp(function (temp) {
    console.log("Temp is "+temp+" degrees celsius"); 
  });
}, 1000);

[/codesyntax]

Testing

View the console window in the Espruino Web IDE

Temp is 24.5 degrees celsius
Temp is 24.5 degrees celsius
Temp is 24.5 degrees celsius
Temp is 24.4375 degrees celsius
Temp is 24.5625 degrees celsius
Temp is 25.3125 degrees celsius
Temp is 26.0625 degrees celsius
Temp is 26.75 degrees celsius
Temp is 27.375 degrees celsius
Temp is 27.875 degrees celsius
Temp is 28.3125 degrees celsius
Temp is 28.625 degrees celsius
Temp is 28.9375 degrees celsius
Temp is 29.1875 degrees celsius
Temp is 29.4375 degrees celsius
Temp is 29.625 degrees celsius
Temp is 29.75 degrees celsius
Temp is 29.5625 degrees celsius

Links

DS18B20 links

Buy DS18B20 from Amazon UK

Buy DS18B20 from Amazon US

3rd October 2016 0 comment

Espruino

Espruino Pico and LDR example

by shedboy71 7th August 2016

written by shedboy71

A light-dependent resistor is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits.

A photoresistor is made of a high resistance semiconductor. In the dark, a photoresistor can have a resistance as high as several megohms (MΩ), while in the light, a photoresistor can have a resistance as low as a few hundred ohms. If incident light on a photoresistor exceeds a certain frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electrons (and their hole partners) conduct electricity, thereby lowering resistance. The resistance range and sensitivity of a photoresistor can substantially differ among dissimilar devices. Moreover, unique photoresistors may react substantially differently to photons within certain wavelength bands.

As you can see later in the schematics its easy to connect one of these to an Espruino Pico, you only require an LDR and a 10k resistor so that this could easily be constructed on a breadboard. I used the following module

ldr

Schematics and Layout

pico and ldr_schem

pico and ldr_bb

Code

A simple code example, we will switch on and off the on board LED 1 depending on the value that’s read. So vary the light to the LDR and see what happens.

Type the following into the Espruino web ide and the Send to your Espruino

[codesyntax lang=”javascript”]

setInterval(function() {
  var light = analogRead(A5);
  console.log(light);
  //the value is between 0 and 1
  if(light >= 0.5)
  {
    digitalWrite(LED1, 0); //led off
  }
  else
  {
    digitalWrite(LED1, 1); //led on
  }
}, 1000);

[/codesyntax]

Links
20PCS x 5528 Light Dependent Resistor LDR 5MM Photoresistor

7th August 2016 0 comment

Espruino

Espruino Pico time on LCD example

by shedboy71 6th August 2016

written by shedboy71

This is similar to the previous example, this time we will display the time on our LCD. If you are familiar with JavaScript you will recognise some of the code

These displays were used in old Nokia 5110 cell phones. It is a 84×48 pixel monochrome LCD display and you can use it for graphics, text or bitmaps. To use the display, you will require 5 digital output pins. Another pin can be used to control the backlight.

lcd5110b

lcd5110a

The display driver is a PCD8544 chip (which is another name for the display), and you can safely run the display off 3.3v

Here is the connections I used

Connection

LCD pin		Espruino Pico
GND		GND
LIGHT		N/C
VCC		3.3v
SCLK		B3
DN(MOSI)		B5
D/C		B13
CE		B14
RST		B15

Schematic

here is a schematic

pico and nokia5110_bb

Code

[codesyntax lang=”javascript”]

var g;

function draw() 
{
  g.clear();
  var t = new Date();
  var time = t.getHours()+":" + ("0"+t.getMinutes()).substr(-2);
  var secs = ("0"+t.getSeconds()).substr(-2);
  g.setFontBitmap();
  g.setFontVector(20);
  var timeWidth = g.stringWidth(time);
  g.drawString(time,(g.getWidth()-timeWidth-12)/2,10);
  g.setFontBitmap();
  g.drawString(secs,(g.getWidth()+timeWidth-8)/2,26);
  g.flip();
}

function onInit() 
{
  clearInterval();
  // Setup SPI
  var SPI1 = new SPI();
  SPI1.setup({ sck:B3, mosi:B5 });
  // Initialise the LCD
  g = require("PCD8544").connect(SPI1, B13 /*DC*/, B14 /*CE*/, B15 /*RST*/, function(){
    setInterval(draw, 1000);
  });
}

onInit();

[/codesyntax]

6th August 2016 0 comment

Espruino

Espruino Pico and Nokia 5110 display example

by shedboy71 6th August 2016

written by shedboy71

lcd5110b

lcd5110a

The display driver is a PCD8544 chip (which is another name for the display), and you can safely run the display off 3.3v

Here is the connections I used

Connection

LCD pin		Espruino Pico
GND		GND
LIGHT		N/C
VCC		3.3v
SCLK		B3
DN(MOSI)		B5
D/C		B13
CE		B14
RST		B15

Schematic

here is a schematic

pico and nokia5110_bb

Code

[codesyntax lang=”javascript”]

SPI1.setup({ sck:B3, mosi:B5 });
var g = require("PCD8544").connect(SPI1, B13 /*DC*/, B14 /*CE*/, B15 /*RST*/, function() {
  g.clear();
  g.drawString("Hello",0,0);
  g.drawString("World",0,5);
});

[/codesyntax]

Links

1pcs/lot nokia5110 LCD Module microcontroller development

6th August 2016 0 comment

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