Raspberry Pi GPIO UART Expansion Board

The design is based on the old Raspberry Pi B Serial Expansion Board. The electronics are updated and several functions are added. Dimensions of the expansion unit: 65 mm x 56.5 mm, standard dimensions of an Raspberry Pi HAT expansion unit
GPIO function expansion:

  • 16 independent GPIO interfaces each with power supply and earthing (3V3 level)
  • 2 independent SPI interfaces
  • I2C interface
  • Standard RS232 interface
  • Infra-red Reciever

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The “MCP23017” Port Expander gives 16 new GPIO Ports

In this article, I’ll show you how to hook up and control a port expander chip with wiringpi2 for python. It’s really easy, and once set up (with about 3 lines of code) you can control your new ports just the same way as if they were on the Pi itself. This is, so far, my favourite new feature of WiringPi2 for Python – although there are some I have yet to play with.

What is a port expander?

You probably guessed from the name, but a port expander is a chip that gives you more GPIO ports. WiringPi2 has drivers for several port expander chips…

  • MCP2301716 ports i2c based
  • MCP23S1716 ports spi based
  • MCP230088 ports i2c based
  • MCP23S088 ports spi based
  • 74×595     –    8 bit shift register

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Using a Level Shifter With the Raspberry Pi GPIO

The Raspberry Pi GPIO pins work with 3.3V logic levels and are not 5V tolerant. If you apply 5V to a GPIO pin you risk permanently damaging it. However, you can easily use 5V sensors or modules if you convert their 5V outputs to 3.3V using a level shifter. This ensures the GPIO pins on the Pi only see a maximum of 3.3V. The shifters are usually bi-directional so they can also be used to allow the Pi to trigger a 5V input with it’s 3.3V outputs.
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Temperature Sensing With Raspberry Pi

The Raspberry Pi lacks analogue input, and while it’s possible to use an Analogue to Digital Converter (ADC), the DS18B20 is a fantastic, easy to use digital sensor that uses the Dallas 1 wire communication interface. Fortunately for us, the Raspberry Pi comes with built in software handling for 1 wire sensors which makes using sensors such as the DS18B20 pretty straightforward.

What is 1-Wire Communication

The Dallas 1-Wire protocol is a method of serial communication designed for simple communication between 1 Master and multiple Slave devices. Serial communication means that data is sent bit-by-bit along a single data line.Read More

PIR Motion Sensor Interfacing with Raspberry Pi using Python

All living objects, whose body temperature is more than 0ºC, emit the heat in form of infrared radiation through their body, also called as thermal radiations. This Radiated energy is invisible to human eye. These Signals can be detected by using PIR sensor which is specially designed for such purpose.

Grid eye illusion

In Passive Infrared (PIR) Sensor, passive word indicates PIR Sensor does not generate or radiate any energy for detection purposes.

PIR Sensors don’t detect or measure “HEAT“; they detect the infrared radiation emitted or reflected from objects.

They are small, inexpensive, low power and easy to use. They are commonly found at home, medical, factories etc. areas.Read More

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