I am very new and unexperienced with wireless control using xbee and i would like to know what parts i would need to control my PICAXE robot with my computer wirelessly.
Yup.
You will need (2) x-bees --DO NOT get the series 2 models-- Get the series one or the Pro models. You will need a X-bee/USB board or some other way of getting some serial data out of your computer and into the X-bee. The X-bee’s use 2mm pin spacing so you will probably need an break-out board to make wiring simpler on the robot side as well. You will also need some sorta terminal program or software on the computer to send the data to the robot. Many people (including me) use Processing for this.
Another route to think about is do the same with a bluetooth module. I think the bluesmirf from sparkfun is the “standard”. You would only need one on the robot and internal or dongle bluetooth on the computer. Might be cleaner and simpler.
i was just having a look at
i was just having a look at the bluesmirf gold bluetooth modem on robotgear.com.au (i live in australia) and what i gathered from it is that it is just a wireless extension for the serial cable and i would use the serrxd and sertxd or the kbin commands to control it. would i be right in saying that?
Agree about BlueTooth with a caveat
I have not done this with a PICAXE, but I have done both xBee and BlueTooth between the PC and an Arduino. Once they are set up, there is no difference. They both appear as serial ports on the PC and are dealt with as TTL level serial ports on the uC end. I use the SFE USB Explorer with an XBee Pro module on the PC end for xBee and just a cheap dongle for Bluetooth. If you go with xBees, I recommend the Adafruit adapter for the uC side if you get a Pro model xBee. there is a problem with the SFE one and Pro models requiring you to short across a tiny surface mounted diode on the SFE (not the USB one, though; it works fine). The adapters work with 5v or 3.3v and only require 4 pins (-,+, Tx, Rx). With BT, there are no extra adapters and the one on the PC end is general purpose and cheap. The BT on the uC end also only needs the 4 pins.
But there is that caveat - if you are going to be using it for real time RC, BT has a major issue with recovery. If you go out of range for even a second, you have to re-establish the connection. To do that, the existing connection has to close and then be re-established at multiple levels on the stack. Sometimes this doesn’t go cleanly. I actually prefer a BT dongle to an internal, because every now and then it gets hung up in a way where the only simple way to clear it is disconnect and reconnect. If you have messed with it much, it would be rare for it to take more than a minute to re-establish a connection, but over 30 seconds is not that rare.
so which one do you think is
so which one do you think is best. money wise, connection wise, range wise, etc…
Yes, this is correct.
To the computer, it appears to just be a serial port just as your current “sync cable” appears to the computer as a serial port. Picaxe does use inverted signals so you may have to play around with T9600 vs. N9600 to get it to talk nice, but that should be about it. Because of this inversion, you may also need to use the serin/ serout or hserin/ hserout commands instead of using the “regular” rx/tx pins. I have been using BT for RC forever without a single problem. Then again, I have never been in a position where I could be out of range.
I am not planning in having
I am not planning in having it as a long distance connection. only within a few metres so now i am thinking to go with the bluesmirf. would the bluesmirf silver be a good option? what bluetooth adapter do you use, Chris?
I did not mean to imply that
I did not mean to imply that BT is weak or unreliable. As long as there are no exterior walls involved, the range is pretty good. But when it drops, moving closer will not magically re-establish it. The 900 Pro xBees I use claim up to 6 miles with high gain antennas on both ends. I use a high gain on one end and a short “ducky” on the other to communicate with a USV. The furthest I have tried it is about a half mile on open water. With just the little “ducky” antennas on both ends, I lost connectivity at about 500 yards in a residential area with lots of trees, but it just started receiving again when I came back in range. BT is more like the 50 yard range with obstructions and maybe 100 without. YMMV…