SparkFun Forums

[DevHyfes]

Hello-

I am looking for something that will allow me to access a bunch of digital and analog i/o via USB. I am building a home-brew automation system and I am considering doing a PC-controlled system, rather than doing everything with switches, buttons and PID Temp controller units.

Basically, I would like some sort of board that connects to my PC (windows or linux) and exposes a bunch of I/O for me to access via a java program. I don't need a micro-controller running its own code- I want that all running on the controlling pc. The sorts of things I would be doing include:

reading several RTD temperature probes
activating one of several solid state relays (some very beefy- 40A 240v- for 5500w heating elements, and some smaller for pumps or valves).

It seems like every product that I view comes with a bunch of added baggage intended for making an embedded system. I don't need that much.

As you can guess, I am really new to control systems. I am good with programming, and good with electrical work. I am a total novice with electronics, though, which is why I am having a hard time settling on whatever bridges between my program and my electrical work.

[rmteo1]

http://www.sparkfun.com/products/762%20?

[skimask]

http://www.sparkfun.com/products/9713



Why use 32 bits when you can have 78?

[rmteo1]

Pins and bits not the same thing.

[skimask]

Pins and bits not the same thing.

Ok, got me there... :doh:

[lyndon]

I have never put this device out for sale to the general public (I build it as part of a larger system), but I have an RS232 board that has a couple dozen digital inputs and 8 solenoid driver outputs. Indicator LEDs on all I/O. Cables for all the I/O are available.

It's not a development board: it's designed to read inputs and control outputs over a serial port using text commands with a few special functions. PM me if you are interested.

[Philba]

I know you didn't ask for a microcontroller but your description totally fits any of the arduinos. Yes, you will have to write some code to make the arduino talk to the PC but that is one step up from printing "hello world". And, there is a huge amount of sample code. Personally, I like the Teensy 2.0, $16 from PJRC but an arduino Uno with a relay shield might be less HW work for you.

[propjohn]

As you can guess, I am really new to control systems. I am good with programming, and good with electrical work. I am a total novice with electronics, though, which is why I am having a hard time settling on whatever bridges between my program and my electrical work.

If you're looking for a solid intro to microcontrollers it's hard to beat Arduino's. It has a very easy development environment to set up and more importantly it makes it easy for a novice to be productive.

The Inventor's Kits (eg. http://www.sparkfun.com/products/11022 ) include a set of tutorial projects with all the necessary components and sensors to get started. Even if you wind up using a different microcontroller, it's well worth the experience.

[Duane Degn]

I recommend SparkFun stuff on the Parallax forums all the time so I think it's only fair I recommend a Parallax product here, especially when it such a good fit for the task.

I'm a big fan of Parallax's Propeller. It's really hard going back to a single core AVR chip after having multiple cogs that can monitor sensors in parallel.

The QuickStart board could probably do all that you need and it only costs $25.

You say you don't need the microcontroller to do anything expect send the data to a PC. Many sensors don't have a way of communicating directly to a PC. The microcontroller needs to read the data from the sensors with SPI, I2C, one wire or some other protocol and then send the data to the PC in some nicely formatted way over an UART. So you will likely need some code to do all this.

Arduinos have libraries to make using these various communication protocols easier, and the Propeller also has many "objects" to make communication with senors and other devices easier.

I have my first Arduino on order but I've used several different AVR chips. For some applications AVR chips are the best choice as a uC, but many, including I think what you'd like to do, are much easier accomplished with an eight core Propeller. (The Propeller is 32-bit and has 32 I/O pins.)

I've listed some of my projects here.

Many of them use the Propeller. Some (maybe most) of them wouldn't be possible with an Arduino.

Duane