If you are faced with a paucity of projects for your Raspberry Pi or RBPi, the tiny, credit card sized single board computer, you should get the circuit boards from Pi-Plates and connect your RBPi to the outside world. Pi-Plates offer a family of stackable, add-on boards that provide your SBC with a robust set of features at a minimal cost.
Pi-Plates design their circuit boards to be economical with the GPIO pins they use from the RBPi header. For example, when using the DAQCplate board, it uses only two dedicated GPIO pins. However, you can stack eight of these Pi-Plates to get 64 digital inputs, 56 open-collector outputs, 64 analog inputs and 16 analog outputs. Whether you are an experimenter, a hobbyist or a professional, Pi-Plates have designed these boards to be useful for all. Additionally, these are mechanically and electrically compatible with all revisions of the RBPi. That includes versions A, B, A+, B+ and the new version 2.
At present, Pi-Plates offer four products. The flagship product is the DAQCplate board that has ADCs or Analog to Digital Converters, DACs or Digital to Analog Converters and expanded digital IO. MOTORplate is a new product for controlling motors and you can use it to drive two stepper motors or four DC motors, while its onboard software can handle all drive logic including acceleration profiles. If you want to add custom hardware on your Pi-Plate stack, you can use the PROTOplate board.
When stacking Pi-Plates, you will need a secure structure and this is provided by the BASEplate mounting system. All hardware necessary for mounting to the BASEplate is already available with each Pi-Plate board. Pi-Plate also offers two great kits.
The DAQC kit comprises two BASEplates and one DAQCplate boards for the price of a single unit. This makes a great beginning for those starting with the DAQCplate for the first time.
For those starting with a MOTORCplate, the MOTOR Kit may be very useful. This kit comprises one MOTORplate and two BASEplate boards for the price of a single unit.
For example, the DAQCplate is a data acquisition and control board. Its digital output section has a connector that provides seven open-collector outputs and a pair of 5VDC outputs that you can use for driving loads. You can protect these with a flyback diode connected to the terminals.
You can use these outputs to drive incandescent automotive light bulbs, ultrasonic rangefinders, resistive heating elements, unipolar stepper motors, buzzers, solenoids, relays, DC motors or LED strings. Green LEDs connected to each digital output light up to indicate a high on the output. To light up these LEDs, you do not require connecting anything to these outputs. At the same time, these LEDs will not affect anything that you connect to these outputs.
Darlington pair transistors drive the seven open-collector digital outputs. They can sink a maximum of 350mA and handle a maximum load voltage of 12VDC. With a load voltage of 200mA, the on voltage is typically 1.1V. When using inductive loads such as solenoids or relays, you must connect the high side power supply to the flyback protection terminal.
