New Project: Driving MAX7219 Serial LED Matrix with OLIMEXINO-85

Olimexino 1

MAX7219 is simple serial shift in/out with LED driver. In this project Mr. Paolo PerCdS demonstrates how 8×8 LED matrix can be driven serially with OLIMEXINO-85

sent via Project page.

New Product: Electromagnetic Door-Lock


DOOR-LOCK is electromagnetic door lock. It operates with 12V DC, when power is applied the door lock pin is moving inside housing, when power is released the pin is moving out by spring.

With SNS-FINGERPRINT and DOOR-LOCK you can make complete access system with logging with platform of your choice – ESP8266, Arduino or OLinuXino.

New Product: Optical Fingerprint sensor SNS-FINGERPRINT adds fingerprint recognition to your next project


SNS-FINGERPRINT is optical fingerprint sensor which will make adding fingerprint detection and verification very simple. Inside there is DSP chip that does the image rendering, calculation, feature-finding and searching. You can teach the sensor for fingerprint images and up to 1000 images can be stored in the internal Flash memory. There’s a red LED in the lens that lights up during a photo so you know its working. In image search mode the sensor compare the current scanned image with the stored database and if images match it sens index number of the stored image which match the current scanned fingerprint.All communication is done by UART.

ESP8266 IoT firmware plug and play detects if SNS-FINGERPRINT is connected to UEXT uart so you can make wireless door access system very easy using just Javascript programming.  We also have demo in Arduino C++ and OLinuXino Python3 so you can access this sensor with any of our development boards.


Energy monitoring with Arduino and current clamp sensor


SNS-CURRENT-CT013-100A is split core current transformer which allow you to non-intrusively measure AC current. It’s safe even for people who do not know electronics as there is no access to high voltages etc.

All you have to do is to clamp the current sensor around one of the wires where the current flows. Note if you clamp the both wires you will not measure anything as the current flow from one wire will neutralize the current flow from the other wire and the sum will be always 0.


The sensor easily clamps around the current flow wire:


On the other end the sensor have 3.5 mm audio jack where you can plug in mating connector and connect to Arduino.

As any other transformerSNS-CURRENT-CT013-100A has primary and secondary windings, the ratio is 100:0.05 i.e. when 100A flow through primary 1 turn wire the secondary coil will have 50mA.

The current transformers must always have burden resistor connected to the second coil, the purpose is to measure the voltage drop on this resistor which will be proportional to the input current. This burden resistor value also should be low enough to prevent core saturation.

Safety: Current transformers should never operate without burden resistor, as if left open very high voltage may generate through second winding which to cause sparking. So never use this sensor without connecting it to proper circuit with burden resistor!

ConnectingSNS-CURRENT-CT013-100A to Arduino is well explained here. We have nothing to add. Based on same setup we tested the emon library and it works perfectly.

We used for our setup OLIMEXINO-32U4 + MOD-LCD3310 and breadboard where two 10K 1% resistors + 10 uF capacitor make the bias circuit to the sensor with 33 ohm 1/4W 1% burden resistor connected.


For device under test we used toaster and we clamped one of the heater wires:


The Arduino code is quite simple:

#include "lcd3310_GPIO.h"
#include <math.h>
#include "EmonLib.h"

EnergyMonitor emon1;
String toPrint1, toPrint2;
double Irms, thePower;
char buffer1[30], buffer2[30];

void setup()
 emon1.current(1, 111.1);  //pin for current measurement, calibration value
 pinMode(8, OUTPUT);   //enable UEXT power supply
 digitalWrite(8, LOW);
 LCDInit();   //initialize LCD display
 LCDContrast (0xFF);

void loop()
 Irms = emon1.calcIrms(1480); // measure current
 thePower = Irms*230.0;   // we assume voltage is 230VAC if you add transformer to connect to other input you can measure real voltage too

 toPrint1 = "Power:" + String((int)thePower) + "." + String(((unsigned int)(thePower*100))%100) + " ";
 toPrint2 = "Current:" + String((int)Irms) + "." + String(((unsigned int)(Irms*100))%100) + " ";
 toPrint1.toCharArray(buffer1, 30);
 toPrint2.toCharArray(buffer2, 30);
 LCDStr(0, (unsigned char *) buffer1, 0);
 LCDStr(2, (unsigned char *) buffer2, 0);
 LCDUpdate();   // print power and current

as you see emon library is very easy to use, so with just few component andSNS-CURRENT-CT013-100A you can easily monitor your home power consumption, log it to the cloud with ESP8266 for instance etc.

When the toaster is switched on the power is displayed:


If you look at the first picture when the toaster is not switched on there is still some 0.012A displayed and fake 28 W energy registered, this is just noise on ADC input. The easiest way is to filter this noise in software and if energy is less 30W to ignore it.

New Product in stock: Ultrasound distance measurement sensor SNS-US020 for range 2-200 cm with 0.3cm accuracy


SNS-US020 is low cost ultrasonic sensor, perfect for your next robot project. It measures the distance by sending ultrasonic waves and reading back when the reflected wave. SNS-US020 operates with 5V and requires only 3mA in active mode. Note that for best results the reflection must be in hard surface, soft surfaces tend to absorb ultrasonic waves and weak the reflected signal.


  • power supply 5V
  • consumption 3 mA
  • distance 2-200 cm
  • accuracy +-0.3 cm
  • working angle 15 degree
  • trigger and echo TTL 5V
  • operating temperature 0-70C
  • dimensions 45 x 20 x 15 mm

Once trigger pulse of 10 uS is detected to trigger IO the module sends 8 pulses with 40kHz and listen to receive the reflected signal, then calculates the distance assuming speed of sound 340m/s. No temperature compensation is used for the calculation so there is error in the measurement depend on ambient temperature.

Signals to be connected:

  • VCC
  • Trig
  • Echo
  • GND

Can be used directly with Arduino with the provided code. Works perfectly up to 200 cm. All claims you will see on the net for similar devices that works up to 4-7 meters are false, so small sender/receiver can’t achieve such distance in real world.

Here is video of the demo project:

New product: The popular HC06 Bluetooth to Serial modules are now in stock


HC06 are popular Bluetooth to Serial modules bases at CSR BC04 Bluetooth technology. They have with build-in 2.4GHz antenna, support Bluetooth class 2 power level and operate with voltage in range 3.1V~4.2V

If you want to add Bluetooth wireless connectivity to your next device without hassle with Bluetooth protocol, HC06 will allow you this working as simple as with UART. The module have AT commands to listen and pair to other nearby BT devices, then you exchange data like if you worked with wired uart.

Tons of Arduino examples are available on the net. The module is made to be easy soldered on your own custom board.

Clean install of Arduino IDE for OLIMEXINO-85 boards


via Olimex Projects page

Paolo PerCdS posted new project how to make clean install of Arduino IDE and add OLIMEXINO-85 board in the IDE.


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