You really don't need a daughterboard to get started with the RPi; take a look here for some tutorials. Some of the projects require some external hardware (breadboards, LED's, etc) .. you can buy accessory kits from several places, including Adafruit & E14.
HTH and let me know if I can provide any more information.
A year ago I got a Christmas calender from Conrad's at about this time of year. Being late in the season it cost a couple of dollars. The contents were a CD4007 ic, a 3 inch breadboard, some leds, ceramic capacitors, and resistors. That may be what you want.
Real instructions for real control of real objects: Hardware; one red led, one 330 ohm resistor, connect them in series with Pins 11 and 13 on the GPIO connector.
11---/\/\/\/---Long led lead---LED---13
>>> import RPi.GPIO as GPIO
The RPi.GPIO module comes with the pi, nothing to install. Google "raspberry-gpio-python" if you need help. One carvate, If you put GPIO code in a module the module and the main program will each need to include the import statement above.
Getting started in hardware: Pins on everything start with pin 1 which is marked with a dot on the top of an IC, a square solder pad on a pc board, a small triangle on ribbon cable connectors, and an odd colored wire on ribbon cables themselves. Component pins are numbered in a circle BUT pi pins are numbered like the houses on a street, a zig-zag pattern. I suggest you cover the 5V pin on the pi connector with shrink tubing, a bit of insulation from a stripped wire, or nail polish as you won't need it and shorting it with a test probe can be a disaster. A solderless breadboard and a few female to male jumper wires to go between it and the Pi for convenience. Always put a resistor (330 ohms) in series with the gpio pins and use 3.3V to limit the drawn current (3.3/330 = 0.010 Amps) which is pi safe. Opto-isolators are suggested between gpio and real world devices. Put a 330 ohm resistor in series with the input (an led) and the pi is protected from spikes of several thousand volts. A 10ma input current and 70V output device can be had for a few cents H11 and the ILO621 (under $2.) offers 4 isolators in a 16pin dual inline package. A shunt capacitor should be used with inductive loads.
The main things you need is a solderless prototyping breadboard - WBU-301J - WISHER - BREAD BOARD, PROTO TYPE 84MM X | Farnell UK https://learn.sparkfun.com/tutorials/how-to-use-a-breadboard - some jumper wires - http://uk.farnell.com/wisher/wjw60b/jumper-wire-kit/dp/1173677 - and a set of resistors, potentiometers, transistors, leds and push buttons (1).
I will go for motors, and other actuators once you get some kind of project in your mind.
You may think, "with that I won't be controlling 'real world things'", and you will be right.
But for a starter you just need to get inputs, compute them and generate outputs. Right now those inputs would be a push button - digital input - or potentiometer - analog input - and outputs would just be a led. But the main principle is the same if the input is a push button, a door contact, a LDR - light-dependent resistor - , a temperature sensor, or a neurosky chip hooked to your brain - not kidding, I get those from mattel Mind Flex games but they just hook to your ear lobe ;-).
The same with the output, you will be blinking a led, but you would trigger a relay to start a high voltage device, give a signal to a stepper motor controller, send a signal to a DC motor controller to start running, or blinking a IR led to turn on/off your TV or HVAC.
You may be looking at analog inputs - LDR, potentiometers - digital inputs - pushbuttons - and how to get those inputs to produce an output - blink a led, trigger a transistor to start up another device.
I will also advice, if you have little experience, to grab an Arduino. Those are sturdy and there is a huge ecosystem to get started.
It also works with 5 volts instead of the 3.3 volts of the Pi. Most hobbist sensors are 5V and interfacing with the Pi may be a pain at start. Even worse if you think the GPIOs on the Pi are not protected so if you plug them to 5V you may fry you Pi.
You can then jump to a teensy 3.0 that's a device with an arm processor and 3.3V like the Pi but where your arduino code will work. You can look into the teensy code to start to understand arm processors.
Then jump to the Raspberry Pi through the arduPi library, taking advantage of the huge amount of Arduino examples around. It's the same API than the arduino but working on the Raspberry. You may even use the some of the same shields through a connector made by the arduPi authors. You can look at the arduPi code to start to understand the Raspberry GPIOs.
Or go for the GertDuino, that's a mix up between raspberry and arduino - it really is a raspberry with an arduino on top.
If you'd rather work directly with the Pi, it's good to get something that makes easy to hook up the Pi GPIOs to the breadboard. I use both the Adafruit adapter 914 - ADAFRUIT INDUSTRIES - PI COBBLER BREAKOUT KIT, RASPBERRY | Farnell UKhttp://learn.adafruit.com/adafruit-pi-cobbler-kit/,and the cooking hacks connection bridge Cooking Hacks - Documentation - Raspberry Pi to Arduino shields connection bridge
The Adafruit one is my recommendation if you don't have - or plan to use - arduino shields.
So my advice. Don't expend money on shields and controllers. Just get some basic components and try to learn to manage the basic stuff. Get inputs, process them, set outputs. A breadboard, wire, a connector and basic components will get you running. After that, to hook up "real devices" is easy. My only advice is if you don't feel too comfortable - or don't know how to - hook wires in your Raspberry Pi get an cheap arduino and fry it instead of your raspberry. Later on, go ahead with your Raspberry and discard the Arduino.
Happy hacking :-)
(1) Example Kit with pots, leds, etc ... for the Pi (includes the connector for arduino shield mentioned): Starter Kit for Raspberry Pi
Same kind of kit for the Arduino - A000010 - ARDUINO - WORKSHOP KIT, WITH ARDUINO BOARD | Farnell UK
Note: those are just examples, to take a component list from those kits and walk with it to your local electronics store - or just buy them all from Farnell - is highly recommended. Those kits use to be quite expensive if you compare them with the individual component's price.
Other links related to this post:
Teensy 3.0 ARM development board with Arduino API - PJRC Store
I'm feeling a bit in over my head and would love some suggestions. My kids and I are interested in learning electronics and especially controlling real world things with computer programs (Motors, solenoids, LEDs, etc etc.) We've been doing things with Scratch and Lego WeDo but we want to take it up a notch both in terms of programming and physical elements. I have a little programming experience but no electronics experience.
Without doing a lot of research I ordered a Raspberry Pi thinking it could directly control things, but now am realizing I need some sort of shield/controller/board etc to do this correctly. I'm a little overwhelmed by all the cobblers/shields/duinos/controllers available, especially since I'm not even sure exactly what specific projects we'll be doing. I wonder if there's a good starter kit for Pi, similar to this that will get us going, that includes components and a manual.
I'm not opposed to buying a Gertduino if that's what I need (Did Gertduinos supplant Gertboards?), but that still doesn't help me as far as components and tutorials.
Thanks for any and all help. I look forward to becoming a contributing member of this community once i figure out what the heck I'm doing.