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FAQ
Introduction
As of now this isn't really a collection of frequently asked questions, but of questions, we think, people might ask. So if your particular question isn't covered here, don't hesitate to contact us - and maybe it makes its way into this collection :-)
How much is one radio hardware?
About 50 EUR, which is about 50 US$. However you need at least two of them for a working system, in a multi client environment every client plus the server each need one device. If you want to try out the system without having to pay so much money, take a look at a question below.
What's the range of the transceiver?
This requires a little longer explanation: The manufacturer says in an application note, that several hundret metres can be reached. However this only applies to free air transmissions with no near sources of radio noise. We tested the range in our school and reached about 50 metres (inside a building in the city). As the nRF401 sends with only very little power at the ISM band that may be used by everyone, the range also greatly depends on whether there are a lot of other devices sending at this particular frequency or not. During presentation at "Jugend forscht 2002" the system worked at a range of about 20 metres, which of course sucks.
I own a TI-xx, HP-xx, ... calculator - is it supported?
Currently only the TI-82 and TI-86 are supported, but porting the software to other calculators is planned. However it's not very likely, that calculators other than the Z80-types of TI will be supported soon as we don't have any knowledge about programming them, yet. For more information on that, please take a look at the "Future" section.
May I assist in hardware and/or software development?
Of course! As we can't spend all days developping the system, any help would be appreciated. However we cannot supply you with hardware for free. Please just contact us and we'd be glad to speak about how you may participate.
The server crashes right after the start
This is a known bug, yet we don't really know how to solve it. On some PCs it works, on others it just doesn't. It would be nice if you could send us a little bug report (what operating system, what TI-Net hardware used). It seems as if the software crashes on computers running Windows XP if something is connected to the selected COM port and if the server is run.
Is it possible to test the system without having to buy and build all the hardware?
As the microcontroller is a fundamental element, you can't just leave it. However it's not really necessary to include the radio transmission, the system works just as well by cable (or even better, as then there's no radio noise corrupting packets). The minimum would be a circuit for the microcontroller to interface the external SRAM, together with few external components. Also a voltage converter (MAX232 or similar) between PC and microcontroller is required. Altogether and including a microcontroller, the parts are available for about 15 EUR/US$.
Of course a programmer for the microcontroller is also required, the parts for the one we use cost about 30 EUR/US$ (15 if you can live without the expensive ZIF socket). If you usually don't need a programmer, you're probably better off spending 4 EUR/US$ more for an SPI capable AT89S8252 instead of an AT89C51. Because of its SPI a programmer for the AT89S8252 can be built for, say, 3 EUR/US$. So for a ready-to-run system consisting of an AT89S8252 plus programmer and the above mentioned circuit you have to pay about 22 EUR/US$.
Soldering SMD is really hard / I don't get the required parts
We have a company nearby, that can order parts and build the devices. So if you're really desperate to give TI-Net a try, contact us and we'll try and find a way to send you built up devices - for sale, of course.
What's "Jugend forscht"?
"Jugend forscht" will translate somewhat like "youth (is) researching". It's a competition for children from 16 to 21 years (there's also a "second league" for the younger people named "Schüler experimentieren" - pupils experimenting). The participants can choose a topic on their own, except that it has to do something with science or technology. People from all around Germany can and do take part. More (German) information can be found at www.jugend-forscht.de. If you are interested in science and live in Germany we strongly recommend taking part some time as it can be a lot of fun.