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Subject: BlueTooth bad, Zigbee good - msg#00002List: hardware.lego.roboticsBluetooth is a very versatile RF-communication that could allow real flexible networking for multi-agent applications. This would be a much faster communication than slow IR. Bluetooth has a maximum range of 30 feet. That's in optimum conditions. You might get down as low as 15 feet in real world applications. At 2GHz or so, it doesn't go through walls very well either. Bluetooth is actually very poor for embedded or robotic applications. It's a power hog, development tools are expensive (try $5000 minimum), true peer to peer modules are almost impossible to get unless you are a Fortune 500 company, and the time required for a BT node to wake up, authenticate, and transmit data is very long. BT is also overly complex for most embedded or robotic applications. The range of 30 feet is not great either. So what is OK? Zigbee is much newer and is designed for use with embedded and robotic applications. The time required for a Zigbee node to wake up, authenticate, and transmit data is very short - less than 1/10 that of BT. Power consumption is much less, and range can be 100 feet or more, depending on antenna design and other factors. Tools are very affordable (sometimes free) and dev kits are $300 or less. There is a Zigbee alliance with a lot of major companies such as Motorola, Samsung, Philips, etc: http://www.zigbee.org/en/about/members.asp Also get this white paper: "ZigBee and Bluetooth: Competitive or Complementary?" at http://www.zigbee.org/en/resources/#WhitePapers We are designing a Zigbee node for use with JCX, (which will finally start shipping this June/July after almost 4 years of development and testing). We are planning on using the Freescale Zigbee chip MC13192. We have a couple of their dev kits which were about $300. http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC13192&nodeId=01752003088166 Properly designed Zigbee nodes can interoperate. What about BT? Vendors are deliberately designing some BT products (such as cell phone headsets in particular) so they don't interoperate for "competitive reasons". Pretty dumb, huh? The "BlueTooth" serial adapters which are available, and which most people point to as BT for embedded use are a very hacked-down subset of BT and are not generally useful. They support only two devices per network, with only serial conversion. They are only useful for short range serial comm between two devices, nothing more. You can get started with Zigbee nodes from Mouser: http://www.mouser.com/dlpdesign/ So to sum up, forget BT for robotics. Use Zigbee. Regards Bruce ------- WWW.SYSTRONIX.COM ---------- Real embedded Java and much more www.jrealtime.com and www.tstik.com +1-801-534-1017 Salt Lake City, USA Thread at a glance:
Previous Message by Date: click to view message previewRe: Nemesis4Lego controllerIn lugnet.robotics, Titus Gabriel Petrut wrote: > All in all, this is a fun project for me, and if there is a real demand, I > will > consider building more units. I will make some Slaves for myself and keep you > all posted with the results. Gabriel, please do keep working on this! It's exactly the sort of thing I've been looking for for years. I get frustrated with the high cost and hard limits of the RCX; it sounds like your units would be far superior in terms of entry cost and flexibility. I can imagine other slave units for things like an LCD display output, a keypad input ("sensor"), and custom sensors like ultrasonic range finder, electronic compass, etc. Incidantally, I haven't managed to see your web site about it yet -- when I tried, you had already exceeded your bandwidth quota! That should give you some idea of the interest among the ALE community in your project. I have extra space on my site, if you'd like, perhaps we can consider hosting your project notes there. Best, - Joe Next Message by Date: click to view message previewRe: BlueTooth bad, Zigbee goodOn Wed, June 1, 2005 12:29 pm, Bruce Boyes said: > Bluetooth is actually very poor for embedded or robotic applications. It's > a power hog You mean compaired to other comm devices, or compaired to a couple motors? I'd think if you have a moble robot, the motors are going to use much more power than anything else, right? > BT is also overly complex for most embedded or > robotic applications. >From what I just read, you can transmit much more data with BT. Isn't that >better? > Zigbee is much newer And, to me, that's a problem. This is the first time I've heard of Zigbee. I know I can go out and get a BT card for my laptop. Or, I can connect with my PDA. Is that same hardware available for ZB? Where will ZB be in a year? In five years? It seems to me that LEGO is NOT a technology company. They don't design or develop new technology. They make toys. Toys that use existing technology. Seven or eight years after the RCX came out, is it still cutting edge technology? No. In fact, I don't think it ever was. But, it's still very cool. I think LEGO has to leave it to people like you, Gabe, and John Barnes, to create cutting edge stuff. They need to stick to solid, proven technology. Steve Previous Message by Thread: click to view message previewNemesis4Lego controllerDanny & all, This was a prototype that I have built with regular parts. If there will be demand, I will make and order PCBs. The total cost of the parts is around $30. Add $10 for labor (and that is verry modest) and you'll get the price. The size can be even smaller than what I ended up with! I mean the height can be 1 plate (for contacts) at the bottom, 1 brick, 2 plates on top. KronosRobotics are the manufacturers of the microcontrollers. Michael Simpson has taken a 16C84 or something like that and created a firmware and uploaded it into these chips. And he created the free software (Basic) so anyone can program them pretty easily. They work like a BasicStamp controller. And the software has a Simulator and a Debug window, where you can see the sensor values, etc. so you don't realy need a LCD. They have 2 controller classes: Dios and Athena. Dios is more powerfull and bigger. Athena is cheap, low speed and memory. In Athena class there are 3 controllers: Athena ($6.95), Perseus ($8.95) and Nemesis ($12.95). Athena and Perseus are great to make the slaves and Nemesis the Master. These controllers do not support multitasking. However, IF someone (i.e. Michael Simpson) agrees to modify the firmware, They can be perfect for small Lego controllers. What needs to be modified? The IR protocol for instance, to be able to work with Lego Remote and talk to RCXs. Perhaps he will do that if there is a real demand. Mean while, I will try to make it work, allthough it is verry hard for me. I am not an engineer and I do not understand the terms and how IR and serial protocols work. All I did was put together some examples and application notes from their website. And after I have read the Boe-Bot manual I understood how to use the Panasonic IR sensors to do proximity detection and even distance measurements (left and right). The controller that I have built (put together) can work with up to 7 Lego active sensors. I have chosen to make it work with only 2, so I can use another 2 input/outputs for 3 pin sensors or to command 2 servos. And of course, 2 for the IR sensors. Actualy, I have seen that it can be done with only one sensor with 2 separate IR Leds. Fire left - measure, fire right - measure. Also, the motor driver has an Enable pin that can be used to ramp up/down the speed verry smooth. The motors are running at 9v like on a RCX. There are more ways to do a master-slave comunication with these controllers. I thought the easiest way to do it will be using the serial bus that is used to program them. This bus has 5 pins: -,+(5v),Rx,Tx,Atn. I am considering adding another pin for +9v, so they can get power from the Master - for the motors. Or, have the slaves have their own Lego power connector... Possible Slaves: 2 sensors slave, using a Athena micro. 4 sensors slave, using a Athena micro. 2 sensors, 2 motors slave, using eighter Athena or Perseus (faster) micro. LCD slave, using a Athena micro. Speak slave, using a AthenaHS and a SpeakJet. All the slaves can have up to four 3 pin ports to connect to servos or 3 pin sensors. All in all, this is a fun project for me, and if there is a real demand, I will consider building more units. I will make some Slaves for myself and keep you all posted with the results. Gabriel Next Message by Thread: click to view message previewRe: BlueTooth bad, Zigbee goodOn Wed, June 1, 2005 12:29 pm, Bruce Boyes said: > Bluetooth is actually very poor for embedded or robotic applications. It's > a power hog You mean compaired to other comm devices, or compaired to a couple motors? I'd think if you have a moble robot, the motors are going to use much more power than anything else, right? > BT is also overly complex for most embedded or > robotic applications. >From what I just read, you can transmit much more data with BT. Isn't that >better? > Zigbee is much newer And, to me, that's a problem. This is the first time I've heard of Zigbee. I know I can go out and get a BT card for my laptop. Or, I can connect with my PDA. Is that same hardware available for ZB? Where will ZB be in a year? In five years? It seems to me that LEGO is NOT a technology company. They don't design or develop new technology. They make toys. Toys that use existing technology. Seven or eight years after the RCX came out, is it still cutting edge technology? No. In fact, I don't think it ever was. But, it's still very cool. I think LEGO has to leave it to people like you, Gabe, and John Barnes, to create cutting edge stuff. They need to stick to solid, proven technology. Steve Loading Comments...
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