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Testing LCD keypad Shield for Arduino

Recently I’ve got an Arduino LCD keypad shield. I haven’t decided yet where it will be used. But why not plug it into an Arduino board and see it working. The shield was initially introduced by DFRobot, who has some cool open-source stuff, including robotics-related. This LCD keypad shield is a cheap and convenient solution for adding 2×16 LCD and five push buttons (+1 reset) to Arduino design. LCD here is interfaced using 4-bit mode and occupies 4 (D4), 5 (D5), 6(D6), 7(D7), 8(RS), 9(E), and ten digital pins. Pin 10 is used to control the LCD backlight through the transistor key. All five buttons are connected to a single Analog pin 0 using a resistor-based voltage divider. This lets us keep other pins for general use. The shield is designed to work with 5V based boards.

Thoughts on interfacing piezo vibration sensor

piezo vibration sensor test with oscilloscope

Some time ago, I purchased a MiniSense 100 Vibration sensor. I probably had some project in mind, but it happened that it dived into drawer among other “to do” things. I thought it’s time to try a few things with it. Piezo sensor MiniSense 100 is very sensitive with a pretty good frequency response and is linear (±1%). As you can see, high sensitivity is achieved with a 0.3-gram inertial mass at the end of the film. As there is a hole in the mass, you probably can screw in an additional mass and increase sensitivity even further. Probably there is no need to explain where such a sensor would be helpful. These could be vibration/ motion sensors, impact sensors, and other areas where motion and acceleration are involved. Usually, sensitivity is 1V/g. Where g is standard gravity or standard acceleration due to free fall and is equal to 9.80665m/s2. As a mechanical device, it also has a resonant frequency of 75Hz. At this point, sensitivity reaches 5V/g.

Understanding and interfacing LDR – light dependent resistors

LDR (Light Dependent Resistor) is a simple, cheap electronic device. This is a resistor in which resistance varies depending on light intensity. You’ve probably seen typical LDR in some projects where light intensity must be considered. They can activate light switches and alarms, adjust display brightness, and more. Light-dependent resistors can be of different types. They vary in light-sensitive material used. Visible spectrum LDR is made using Cadmium Sulphide (CdS) or Cadmium Selenide (CdSe). This material is sensitive to the wavelength range from 400 – 850nm. For the near-infrared spectrum (1μm – 3μm), there are PbS or PbSe materials used. For the deeper infrared range (3μm – 1000μm), there are InSb and InAs.

Drive DC motor using Arduino motor shield

This is a continuation of the previous post where we have tried to run a servo using an Arduino motor shield. This was a simple task to do with the Arduino Servo library. Today we will push things a bit forward and drive the DC motor using the same motor shield. This motor shield can run small DC motors that require less than 0.6A of current and operating voltage is less than 25V. In my drawer, I found a small 12V motor that will fit this demo. Before we begin programming, we need to connect the motor to the Board. We are going to use the M1 connector.: Since the motor requires a 12V power supply, we are going to use an external power supply. It can be connected to the External power screw terminal. Be sure to remove the jumper as well.

Testing Arduino motor shield with servo motor

Recently I’ve got an Arduino motor shield. It is based on ladyada first mshield circuit. It uses two famous L293D quadruple half-H divers. It is a cheap and reliable shield to drive various motors. These can be two hobby servo motors, four bidirectional DC motors, or 2 (unipolar or bipolar) stepper motors. The load current is limited to L293D chips. The specification says that each channel can provide a constant 0.6A and peak 1.2A. There is also a thermal shutdown to prevent the circuit from damaging. Motors can be externally powered using a voltage range from 4.5V to 36V. Each motor control channel is pulled down with a resistor to disable any motor at power-up. In this post, we are going to try servo motor control. There are a couple of connectors on the motor shield where you can connect two servo motors using a standard 3 wire connector (GND, VCC, and PWM).

How to calibrate touch screen display on STM32 board

Touch screen displays are a common choice in many microcontroller projects. Touch capability won’t take additional space – it sits on top of LCD to directly interact with objects you see on screen. To get this working, touch screen coordinates must match screen coordinates. So could be sure when you touch the point on screen you point where you want. The touch screen is an analog device. It is made of two flexible resistive sheets with a gap between them. When the screen is touched, a connection between sheets is made, and thus a measurement of voltage drop is taken. Normally resistive touch screen has a four-wire configuration. And normally, a specialized IC is used to take measurements and send data to MCU for processing. In our case, we are dealing with the ADS7843 touch screen controller, but in other systems, this works the pretty the same way. The fact is that the touch screen controller reads screen ADC values and passes them via the SPI interface. So all you get is raw ADC readings that are not lined up with LCD coordinates. As you know, LCD screens can be of different resolutions, different orientations, so data gathered from resistive…

What microcontroller development boards I have

During this time, I’ve been purchasing or building various microcontroller boards. Most of them were used to try things out or because they were cheap to get. So I thought, why not blow dust away and see what we have here. Maybe there will be some fresh thoughts on where to use them. Probably I should spare a few words about each of them.

Facts about Raspberry Pi that make it popular

Is there anyone who didn’t hear about Raspberry Pi? It’s like the second thing after Arduino. And this is the result of the right idea at the right time. Many Linux boards around that don’t cost a fortune, but they didn’t make it to the masses. And mainly, they were used by advanced users who know Linux well enough. Raspberry Pi pros Raspberry Pi changed things pretty drastically. And there are several key factors why:

Basic touch screen routines up and running

STM32103ZET6 prototyping board comes with LCD having touch screen capability. It is a great way to interact with the device. Practically speaking Touch screen is a resistive film that can be accessed as a regular potentiometer which value depends on the touchpoint. Depending on voltage drop, it is possible to calculate the coordinates. There is a touch screen controller that takes most of the hard work – it has an internal ADC that measures the voltage and sends a value to the microcontroller using one of the selected interfaces (I2C or SPI). There is a typical ADS7843 controller used in the board, which talks to the microcontroller using SPI. After playing around, I’ve put a messy code that reads touch screen coordinates. It is a glued code from various sources, so it is only to fix some results. Currently, the code reads many values, then averages to get rid of most garbage, and then calculates screen matching coordinates. This is the trickiest part to do. You can do this empirically by reading min and max ADC values for each axis and then calculate coordinates using formulas:

Online signature healthcare

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