I'm a somewhat long-time lurker who's just getting started with Netduino. I've been scouring the internet and trying to get an idea of what is compatible with the Netduino.
I'm dying to get started, but I'm not entirely sure of the scale of Netduino's capabilities. I've seen all manner of awesome projects, from SMS controlled sprinkler systems to garage door openers. My first Netduino project was a servo that changed positions every 12 hours to switch my floodlights on and off, but it was just physically actuating the switch.
And now for the obligatory noob questions...
1) Would it be possible to build something large? A robotic arm that could pick up things based on their color perhaps?
2) What would be required to make something like this happen?
3) How do you run power to a large motor, but control the logic with Netduino?
4) How would I interface with a sensor purchased from parallax such as the Ping?
5) If I were to purchase a sensor, how would I create a way to interface with it if no documentation for it is available?
So many questions!
Welcome to the Netduino world where nearly everything is possible. I've numbered your questions in the quote above to match answers below. I'll try to give you my perspective and I am sure others will chime in with theirs.
1) You can certainly build something large. Really depends on the processing power needed and how many GPIO pins are needed to control devices however the limit of 13 GPIO pins can be overcome with multiplexing or going with a GO Bus style architecture. So really you are bound by the storage space for your program and the processing power needed to execute the program. I consider my project (Pandora's Box) small to medium (just to give you an idea). It has sensors for temperature, humidity, barometric pressure, accelerometer, magnetometer, gyroscope, xband, and PIR motion as well as Ping (ultrasonic) and laser distance measurement. It has a 4x20 LCD screen, 5 way joystick, real time clock, LiPoly Charging and monitoring capabilities as well as an on board web server for access to the logged data (which is taken from the sensors 3-6 times a second as well as the ability to control the board via the web interface. I am just about maxed out on storage space for the application.
2) So, at a high level to make your "robotic Arm happen"... if you were starting from complete scratch... you would likely be building a 5 or 6 degree of freedom arm so you would need all of the parts to build the arm, the 5-6 servos and motors to control it and a gripper with it's servo. You would then need a motor controller and there are so many. They are externally powered but controlled by the microcontroller. They make them in Serial, I2C as well as you can control the servos directly with the PWM pins but you are limited to 4 on the Netduino I believe. You would also need the vision system. With the Netduino you cannot handle live streaming video for recognition so it would have to be done by single camera shots or using the means of other sensors to monitor the environment then determine the color of the object(s). There are devices like the PING you mentioned that can be used to detect distance and sensors that detect color. These would likely need to be on a rotating mechanism to scan the surroundings or even at the end of the arm near the gripper (kinda like Doc Octopus from Spiderman had eyes in his tentacles). Again this is just a high level overview not specifics.
3) As mentioned above, most motor controllers are external powered for the motors then have an interface either PWM, I2C, Serial to control them.
4) There are already many classes written for various sensors out there. Best way is to ask on the forums or search the forums. I have one I am using for the ping that returns the distance in CM. Basically the ping has 5V and GND to power it and a Signal (SIG) line. When you are ready to PING, you send a 10us pulse to the Sig pin using a tristate port on the Netduino, this tells the PING to send a 40khz sound wave out then you turn the the tristate port to read and wait for the return signal. This is the amount of time it took to bounce back and is used to calculate the distance.
5) I have come across very very few sensors with no documentation. The few I have purchased from China that had to docs usually were copied or designed using the same chipset that other sensors use so you can use their documentation. If you absolutely have no docs you can still try to find the chipset documentation and figure out how it works from that doc and using an oscilloscope and other meters.
I hope this gives you some starting perspective. Feel free to keep asking away.
