The joystick proposed here is much known between makers. It provides two axis and a key button and every axis is actually a potentiometer: that means axis data is analogue and we need to use ADC to read its positioning.
Potentiometers are provided of springs so, without forcing, wipers are approximately positioned in the centre of the two resistive elements. As this device is very simple to use, it is not easy find a related datasheet. Indeed, for the most of the applications, it would be useless. Anyway, joystick used in this demo is a very cheap one marked as continue reading...
We have already introduced MAX7219 in STM32, ChibiOS and a 8×8 LED Matrix, so we are going to jump directly to code section. For convenience we just report link to documentation:
Note that even if pins are arranged in a different way, pin-out remains the same of the 8×8 LED matrix.
In this demo we are going to use Code-B decode to write with ease some number on our 8 digit 7-segment display.
In the demo shown in the video above we set up MAX7219 as normal operation mode, Code-B decode mode for each digit, scanning the whole display with the maximum continue reading...
Using Infra-Red for remote control is a technology born in the 70’s and after 40 years it is still used because the good ratio performances-costs and low power consumption. IR remote require a line of sight, because of that latest remote includes bluetooth technology.
Today it is possible to buy a small remote and receiving circuitry spending a few dollars. In Embedded system using IR could be a fast and cheap solution for remote control even if nowadays RF, Bluetooth and WiFi modules are very affordable.
Searching documentation for cheap devices is often not easy at continue reading...
Widely used in sound mixers, the slider can be used as input for many applications. There isn’t so much to say as this device is made by two potentiometers working together. Indeed, when the cursor slides, it changes the position of two side potentiometers.
The slider shown in Fig.1 has six pins:
VCC, (are two connected together) connected to power supply 3.0V DC;
GND, (are two connected together) connection to ground;
OTA, middle pin of potentiometer #1;
OTB, middle pin of potentiometer #2.
We can sample both OTA and OTB making mean to better evaluate slider continue reading...
The MAX7219 is a compact, serial input/parallel output common-cathode display driver. Included on-chip there are a BCD code-B decoder, the multiplex scan circuitry, segment and digit drivers, and an 8×8 static RAM that stores each digit. Only one external resistor is required to set the segments current.
This chip is often used to drive 7-segment display having up to 8 digits or up to 64 individual LEDs. It is not unusual find this chip in DIY kits to be mounted on a small PCBs like that used in this article (See Fig. 1).
This chip could be found in different packages continue reading...