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  • Author Author: balearicdynamics
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Essential Raspberry Pi Peripherals #1: GPIO and Other Connectors

balearicdynamics

With this first post we start off on something of an adventure, experimenting and experiencing one of the most fascinating aspects of this SBC (Single Board Computer): connecting the device with the real world.

(note: here we consider working with a Raspberry PI 2 but almost all the mentioned features and possibilities will apply to the previous models).

 

Connecting the Raspberry PI to Something Else

One of the most interesting features of the Raspberry Pi is that it includes most of the features we need to interact with the real world. Firstly we have the GPIO, which is the array of pins giving the option to interact with the world through many sensors, communication protocols, motors, LEDs and so on.

 

But that's not all. There is more, and the possibilities go beyond what we can imagine.

 

Just as a reminder, take a look to the following image:

image

Seems incredible, the connector we find in this credit-card sized device:

 

  • 40 Pin GPIO (General I/O ports): can be used for powering low consumption devices, connect I2C protocol external components, Input/Output digital signals, SPI (CLK, MISO, MOSI) protocol, TTL Serial TX/RX pins.
  • 4 USB2 ports: that means, on a Linux-based system, the possibility to connect a very wide range of USB devices.
  • 1 HDMI video and audio output: the HDMI video and audio output supporting full 1080P HD format gives the possibility to manage any display ratio (software configurable) with high quality audio. This feature makes the Raspberry PI a good base machine to make a good quality media center, game device and more.
  • 1 combined 4-pole 3.5 mm Jack connector for stereo output and composite video output: ideal when an HDMI monitor is not available.
  • 1 10/100 Ethernet RJ45 connector: for LAN connection as an alternative to the wireless WiFi when using a USB WiFi dongle
  • 1 camera connector: this connector is ready to work for the Raspberry PI camera that opens the door to an entire world of possibilities, from image shooting up to video capture, streaming, image processing and more.
  • 1 display connector: for small projects the use of a full sized external monitor may not be necessary, so a small screen (better if it's a touchscreeb) directly connected to the Raspberry Pi can be a better solution.

 

When the device is in your hands you have got the keys that open the door to an incredible new world.

 

All that glitters is not gold

In fact, this board can't do all that much on its own, solve ANY problems, or replace all your computers. But it can do a lot for sure. Looking in-depth at the Raspberry Pi connectors and functions it seems that some "advanced" features are missing. For example, it'd be better if the Ethernet was 1Gb instead 10/100 only, better if the boot was from something different than an SD card, better if there was also an audio input, great if the GPIO also included some manner of analog input, and so forth.

 

It's true, but the Pi does have the great advantage of stability: many of the apparently missing features are compensated by its extreme versatility and - why not? - our ability to create great projects, including those parts expected but not present. In my personal opinion this SBC remains one of the most complete, versatile and well equipped low-cost devices supporting Linux.

 

An overview on the next posts

To close this introductory first post on the Raspberry Pi peripherals the following is a list of what you can expect in the forthcoming series.

 

#2 Setting up the HDMI monitor

Despite the HDMI connector, not all the monitors support the same resolution. And the Raspberry Pi shares its video memory with the rest of the available RAM, so it's useful if you can totally control the display parameters (frequency, resolution, aspect ratio, video memory) simply by changing the operating system display configuration file.

 

#3 An introductory approach to wired and wireless networking

There are more options than simply plugging the LAN cable in the Ethernet port of the Raspberry PI. In this post we'll see how the Raspberry Pi can be a flexible networking device, acting as bridge, access point, wireless device and more.

 

#4 The Raspberry Pi camera beyond the webcam limits

Thanks to the power of Python and the specific characteristics of the Pi Camera it's possible to specialise the Raspberry Pi as a video/photo station: shooting, filming, image processing for a lot of possible applications; from photography to security, from stop-motion to the time-lapse filming.

 

#5 Lirc and IR controller: extending the limits of keyboard and mouse

With a very simple hardware approach we introduce the first non-conventional peripheral connection. Thanks to the Linux lirc library we can use a simplified HID (Human Interface Device) - a TV infrared control - to manage programs, device behaviour, and more.

 

#6 Enhancing our Pi projects with the Pi touchscreen

We will see how we can setup and integrate in our projects the Raspberry Pi 2.4" touch screen device.

 

#7 Enhancing our Pi projects with the PiFaceCAD LCD display

When a simple message is sufficient to control the Raspberry Pi behaviour but some control buttons would be useful, the PiFaceCAD (Control and Display) is the ideal device, which can be stacked on our Raspberry Pi for mobile, battery-powered applications.

 

Bookmark this page and the Ultimate Guide to Getting Started with a Raspberry Pi page to stay tuned to this essential guide to Raspberry Pi peripherals, folks!

  • in reply to Robert Peter Oakes

    If some is running wall socket plug wires through these little relay terminals that can barely take a wire larger than 18 awg they have severe personal problems. These small relays are good for controlling lights on autos, motorcycles, bikes, and lights in the home if the wall socket is transformed with a big brick like a computer has to low voltage and amperage.

     

    I see that the first tutorial that they did with the 30 amp relay was a to finish a project that was started and posted online to control a microwave oven with an Arduino. They could not finish it because they could not find a good relay to turn it off and on with, but with the 30 amp relay they were able to finish, SCARY! You can weld scrap steel with high voltage around 30 amps and above, HANDLE WITH CARE!

     

    When working with dangerous projects you must ALWAYS determine a safe way to proceed, if the design failing means you get electrocuted or a fires starts or the project is HOT and it can't be safely unplugged, well you need to redesign until you have an assured SAFE way to proceed.

     

    The very reason Grove has so many relays is so that people can build things correctly.

  • in reply to e14 Contributor

    Low voltage is ok from a safety perspective unless your upping the power consumption to very high levels, the dangers I am talking about is from electrocution, in the first relay it is way too easy to probe near the logic inputs and accidently find the mains (110V, 220V ac wall outlet power kind of Mains), you can either fry electronic equipment like scope or power supply, or if your unlucky... You. and sometimes the reaction to being zapped can be more damaging than the shock itself. if you look at the image of the 30A board, you will see that the mains side is on the other side of the board to the logic inputs and the board even has a slot cut into it to increase the creapage space, even further reducing the risk of mains voltages and surges reaching hte low voltage side, it looks like a nicely laid out board.

     

    The brick one and others are build with the mains (High Voltage connectors ) right next to the logic level inputs, this is just plain BAD layout in my opinion if it is claiming to be safe for 110V and above, way too easy to touch or short out low voltages and high voltages

     

    Now if your using hgh current loads then you still have the risk of starting fires if you overload things but due to the lower voltages (assuming it is not mains high current loads), you should be safe from electrocution

     

    We see all to many times a design that does not adequitly consider the user, yes some of the bad ones may even meet code, but sometimes code is not enough for a beginner / home hobby engineer as they may not be as aware of the dangers and find out the hard way

     

    lastly, my comment is not necessaraly aimed at you macyoda, but a word of causion to any one reading the article

  • in reply to Robert Peter Oakes

    Mains related control.

     

    I have a project where I control a battery with specialized cheap battery relay, this is the main, that is guaranteed for thousands of cycles, with a low voltage relay in a plastic box that is computer controlled, everything must be paired to its rated amperage.

     

    I also check the reviews when buying a high power relays to see if people are complaining about bad behavior when failing, it should not switch when failing or at least be predictable when failing.

     

    I am totally a beginning with these things but I have gone very deep into the few things that I have done. I am very good at building high quality devices and even inventing things even when I don't have much experience, I know how to learn things vertically and horizontally simultaneously so I can go very very deep in specific areas quickly.

  • in reply to Robert Peter Oakes

    Please be specific, what dangers are you referring to.

     

    For example, I have fried a small power supply, thus when I use them I ensure that they are separated and on something nonflammable, this is a constant consideration when hobbying with electronics.

     

    This would be a problem with both Brick and Grove, although MUCH MORE SO WITH BRICK since I see they are using extremely low quality relays and people in this forum are buying and recommending those parts.

  • in reply to mcb1

    Mark look closely at this relay that was in with the group of Bricks that you linked.

    Electronic Brick - 5V Relay

     

    Standard 5v relays ...

    http://www.seeedstudio.com/depot/Electronic-brick-5V-Relay-module-digital-p-479.html

    http://www.seeedstudio.com/depot/Grove-Relay-p-769.html

     

    Look how small it is compared to a standard 5v relays, it is tiny so it probably will not last very long. Quality electronic parts, especially relays, always give a number of cycles that it is expected to last, if the cycles are not listed it is certainly an extremely low quality part and will not last long at all or will be dead on arrival.

     

    I know these things because they are also exist with computer parts.