Transceiver suggestions

joelman

First off, thanks to everybody who's helped me so far. I'm ready for the next step in my plan for world domination.

I'm designing a couple of devices which will need to communicate via wireless link. I looked at parallax's transceiver module, which is sweet, but pricey, and I'm currently looking at the Easy Radio transceiver (ER900TRS-02):
http://www.active-robots.com/products/radio-solutions/radio-modules.shtml
or combining a cheaper transmitter (TWS-434) and receiver (RWS-434):
http://www.rentron.com/Stamp_RF.htm
The advantage of the latter is price, and the fact that they have bs1 code. I might be willing to spring for the extra $ (pounds, actually) for a package that would be more convenient, which it looks like the ER is. I just need to find some bs2 schematics.

Anybody have any opinions/suggestions? Any experience with either of these products and the bs2?

Thanks in advance
Joel

Jim Richey

In an effort to save a little money,you will harm yourself by using an alien product.Only with Parallax will you have access to the great amount of knowledge present here.

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Thanks, Parallax!

joelman

So are you saying that 1) You discourage Basic Stamp users from using 3rd party (alien) products with the bs2, or 2) You discourage such discussion on this board, or both?

I'm new here and I just want to know what the standards are.

Thanks,
Joel

Paul Baker

You are more than welcome to ask about interfacing non-Parallax products with Parallax products on the forum, you can even discuss topics that have no Parallax products in them at all if you conduct the discussion in the Sandbox forum. One of the modules you linked to shows how to connect it to a BS1 and provides BS1 code, so you should have a reasonable expectation for success.

The problem with 3rd party RF products is there are a ton of them, literally hundreds if not thousands. By sheer statistics, the likelyhood of someone on these forums having direct experience with module X is vanishingly small, and since you are talking about interfacing with a hardware product, troubleshooting cannot be done by someone who does not have access to one. That is why most people, including non-employees try to steer people to Parallax products, becuase you can be assured someone has access to one, the least of which, one of the Parallax employees who answer user questions. Almost any type of accessory you can purchase from Parallax can be found cheaper elsewhere, but theres a very good reason for that, the other companies typically have·a single person to assist with technical questions if they have any at all. Parallax has 4 who visit the forums everyday, and who can get other employees onto the forum if thier expertise is needed. Its the old adage, you get what you pay for, and with Parallax that is unbeatable customer service.

If you decide to go the non-parallax route for your RF product, I would also check out www.sparkfun.com they have a couple tech people with limited experience (ie they cannot answer all questions about all of thier products, like Parallax can with thier products), but they have a fairly active user forum. Cheaper, but a lower level of customer service.

Good luck, and welcome to the world of stamps.


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·1+1=10

Post Edited (Paul Baker) : 11/15/2005 2:29:56 PM GMT

allanlane5

Well, first of all, Jim Richey does not work for Parallax, nor do I myself. So neither of us can give you 'official' Parallax policy. All I can do is summarize what I've seen over the past year or so.

Second, Parallax encourages all kinds of 'alien' products to be used with the BS2, and documents lots of them. ULN2803 Darlington Arrays, 7-segment LED drivers, H-Bridges, Servos, IR drivers and decoders, etc. etc. They have a lovely set of articles in the "Nuts And Volts" section.

Things that are frowned upon include recommending some other company's processor or compiler, or asking how to solve some problem in some other company's compiler. Trying to reverse engineer the Parallax PBasic run-time is considered unfriendly, since that's the company's bread and butter.

And Parallax has published the schematics of the BS2 OEM version, the BOE board, basically everything you might need to apply the BS2 in all its flavors. In fact, in all the questions you've asked so far, I've found nothing that would be considered objectionable -- lots of people want to RF-enable a BS2 connection, and the parts you've mentioned have been mentioned before.

LoopyByteloose

Generally, one cannot discuss what they don't know about and do not have. Paid employess are not expected to provide you with such services, especially when they have a similar product to support. That is the foremost reason you will get less support with such products.

Secondly, Parallax will be more diligent than many other vendors with making sure you have an operable device and understand how to use it. They feel very strongly about providing education which is time consuming. When other vendor's products fail to provide schematics, documentation, etc. it really becomes awkward for Parallax to step in and rescue you. You decided to buy cheaper and that tacitly implies much less of something.

Thirdly, Parallax seems to be much more generous than most enterprises, so even though I may buy another product and try to mix and match - it is done on my own when it is done. Respect of a good thing is not really intended to be the creation of a taboo.

There are priorities here. I belive that saftey come first above all others, then customer satisfaction and fulfillment, and finally fun.

You will find the Parallax can be very candid about other companies being better at something, so I don't consider it an exploitive attitude. Simply, it cost more to put your textbooks on-line for anyone to download for free and to provide highly accessible support via this forum. They would rather be Parallax than be all things to all people.

There really is no free lunch, but there is certainly room for kindness, mutual respect, and good fun.

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

bobledoux

There are projects when the Stamp, because of cost, or speed, is not the best choice. But think about the tradeoffs in time. Here is an example:

I'm currently working on a project to add an RF temperature communication link to a Stamp-based instrument package I use in a hot air balloon. Currently, a thermister reads the temperature inside the balloon envelope, using a wire link down to the basket.

My intent was to replace the thermister with a Dallas DS18S20 digital temperature sensor that would be powered by a PIC 12F508. Communication is with the Radiomatrix 433 mhz AM transmitter and receiver that costs about $10 for the pair.

I needed a low cost throwaway transmitter assembly because the unit is exposed to heat, abrasion, shock damage and loss due to its placement on the exterior of a balloon envelope.

I soon discovered that the cheaper the RF unit the more difficult it is to get a successful data link. I have spent more than 150 hours successfully working out a mechanism to get the receiver to reliably read the transmitted signal. Numerous experiments using 4 different receiver circuitboards were tested.

The final alogrithm works. Briefly, the Stamp turns the receiver on to pick up the signal, and then turns it off. I could not get reliable data transfer with the receiver continuously running. The algorithm involves Manchester coding and uses the methods described in the Microchip KeeLoq [noparse][[/noparse]tm] Technical bulletin TB045 (DS91045A).

Making these methods work was not a trivial exercise. Creating working communication between microprocessors can be a headache. Add RF to the data stream and it takes real commitment with the developer sometimes being committed.

Bottom Line: There are very good reasons to pay the extra money to Parallax to buy components that have been tested and work. Reinventing the wheel is usually false economy.

Post Edited (bobledoux) : 11/15/2005 2:41:20 PM GMT

joelman

Gotcha. Thanks (everybody) for the clarification, and sorry if I sounded prickly. I am definitely impressed by Parallax's level of support.