Hi,
I have a mechanism hooked up to my arduino which basically run a simple servo motor if a signal from the computer's USB port to the arduino USB port. What I'm wondering is that this seems to be overkill for a simple project. Is there a substitute for the arduino here? The arduino is also externally powered incase the USB power dies. Something that can run a small servo (runs off arduino 5v output) and has a USB port (I don't have any serial or parallel on the laptop that it runs off), optionally externally powered and can process some sort of signal from the computer to the USB and preferably can interface with python easily.
Does anyone have any suggestions?
Thanks in advance
Sorry, I thought it made sense, but maybe it didn't.
Anyway, the arduino waits for a message from the USB (from the laptop), and if the message is the correct one, it runs the servo for x minutes. If the message is the wrong one, it keeps on waiting until the message from the USB (from the laptop) is the correct one. Once the servo runs, the arduino "sleeps" or pause for y minutes, then it wakes up and waits again for the message from the USB. Does this make sense? This is more or less what the arduino is doing.
So, you need some device that can read serial data, interpret it, send appropriate signals to a servo, enter sleep mode (why?), and re-awaken.
The Arduino sounds perfect for this. Why do you need to change something that works?
If it's to free up the Arduino for something else, google "standalone Arduino" to find out how to build a minimal microcontroller.
Or, get one of the mini versions of the Arduino.
I'm using the USB Bitwhacker for a coule of projects at the moment, and I don't recommend it: its development environment is poorly documented (the compiler is fine, but the USB library is a dog's breakfast that's been eaten and regurgitated), and newbie-unfriendly. I wanted to go with the Teensy for prototyping, and a USB AVR for production, but there are serious supply problems with the chips. The Teensy can be programmed with the Arduino IDE by adding some plug-ins.
Someone was asking about I2C servo chips the other day, and I think I saw a USB-to-servo gadget when I was looking for info to respond. But, if it does exist, it's not going to be a whole lot cheaper than an Arduino, because it won't be made in the volume needed to bring costs down.
You have....
PC > > Arduino > > servos
... and you want to cut out the Arduino?? Why not cut out the PC??
Once the servo runs, the arduino "sleeps" or pause for y minutes, then it wakes up and waits again for the message from the USB. Does this make sense?
Not really. If you use the usual kind of RC-servos, they need to be refreshed every 20ms or they won't keep the position under load. So no napping time for your Arduino.
If you talk about mass production, you could do the same with one of the small Atmel (or PIC if you prefer) processors, which will get the production costs down by a sizeable amount. But for that, from your questions you definitely lack the know-how. You wouldn't ask such question if you were even close to understand what's necessary.
Korman
The reason I wanted to substitute the arduino is because i wanted to utilize all of its functions, not just 1 function. It seems that the arduino is better suited for more complex projects (e.g. running more than one servo), so I just thought if there was a "smaller" (functionallity-wise) arduino.
and yes, i have yet to look into any PICs yet but from the sounds of it, it looks like the arduino is unsubstitutable (?) here
It really depends on the cost. Can you do cheaper with something simpler? Yes, that is possible, either by building your own or with other products (eg STM8/ST7 from STMicroelectronics, PIC, ATtiny). If you can do what you with the Arduino and you don't want or can't use any of the cheaper alternatives, the Arduino is the cheapest way to do it even with all the wasted power.
Korman