Raspberry Pi 3B+ can operate without wall-wart power supply! But how it is possible?!
The new Pi 3B + is the first minicomputer in the Raspberry Pi series that can be powered without using a standard AC/DC adapter. The auxiliary voltage necessary to power the Pi 3B+ board can be supplied using the Raspberry Pi PoE HAT board. As the name suggests, this hardware extension allows powering the Pi 3B+ via Ethernet port. Currently, only Pi 3B+ and Pi 4B models supports such power supply to be implemented, thanks to four additional pins that support communication and power supply using the PoE HAT overlay. This is a particularly convenient solution because the supply voltage, as well as internet connectivity, is provided by a singular cable. The design of the "Power over Ethernet" module is based on switching mode power supply with isolating transformer that stepping down the Ethernet voltage level which is between 37V and 57V, to 5V, following the specification of power supply requirements for the Raspberry Pi 3B+ board. The designers also took care of efficient heat dissipation. The PoE HAT extension board has been equipped with a cooling fan. Thanks to this, the cover can also be used in devices operating in industrial conditions with elevated ambient temperature.
Raspberry Pi 3B + - a great computer for animation designers
The PiMoroni Unicorn pHAT module is equipped with RGB LEDs arranged in a 4x8 structure. It is a great tool for creating simple images and animations. The kit comes with a diffuser that makes the effect of light scattering emitted by the LEDs. The overlay is compatible with GPIO ports on the Raspberry Pi 3B+, and communication is carried out through the SPI interface (Serial Peripheral Interface). A powerful STM32F processor is used as the master controller for the Unicorn pHAT board. Thanks to this, you can connect several independent Unicorn overlays to a single Raspberry Pi 3B+ board. By using the Unicorn Paint program, you can create and upload animation data to the on-board memory of the module via web browser. The board is factory-equipped with a Python software library that you can use to set the optical parameters of the RGB LED matrix.
Hardware extensions for controlling the speed and rotation direction of DC electrical drives
MOSFET transistors were a sign of constant development and a great revolution in electronics in the broad sense. With a low voltage applied to the gate, you can control the high current that flowing through the drain-source channel. This huge advantage of MOSFET transistors was quickly used to build audio amplifiers, as well as devices controlling the powering condition of electrical devices in a quite similar way as a throttle in a car or lawnmower. Now you can do this control on your desk for a little money! The Adafruit Minikit overlay includes two TB6612 integrated circuits that enable control of rotation direction and rotation speed of electric motors. You can connect typical DC motors as well as stepper motors to the overlay. Communication with the Raspberry Pi 3B + computer is carried out via the I2C interface, supported by a 40-pin GPIO connector. A single Minikit overlay can control up to four DC motors and two stepper motors. The current efficiency for a single motor is 1,2A in a long-term working and 3,0A in a peak for a time of 20ms.