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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7-segment Display Modules and the Raspberry Pi

7 segment displays are a well established way of electronically displaying numbers and a small set of letters. They’ve been around for as long as I’ve been playing with electronics but were a pain to wire up given the number of LEDs involved.

Luckily things are a lot easier now that they are available on pre-made modules that uses an SPI interface. This is easy to setup and use on the Raspberry so for about £3 you can add a strip of 8 7 segment digits.

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Enable SPI Interface on the Raspberry Pi

The Raspberry Pi has an SPI (Serial Peripheral Interface) bus which can be enabled on Pins 19,21,23,24 & 26. It is a synchronous serial data link standard and is used for short distance single master communication between devices. As far as the Pi is concerned this is usually relevant to certain sensors and add-on boards.
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Driving Maxim MAX7219 7-segment Display Modules

7 segment displays are a well established way of electronically displaying numbers and a small set of letters. They’ve been around for as long as I’ve been playing with electronics but were a pain to wire up given the number of LEDs involved.

Luckily things are a lot easier now that they are available on pre-made modules that uses an SPI interface. This is easy to setup and use on the Raspberry so for about $3 you can add a strip of 8; 7 segment digits.

These modules tend to all use the Maxim MAX7219. This IC does all the hard work and we can communicate with it using SPI and a few lines of Python.Read More

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