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Outdated BTnode rev2.2 Documentation!! Please find up-to-date information at the new BTnode site: www.btnode.ethz.ch !!Go to: [Overview], [Hardware], [In-system programming], [Development tools], [Software]. Overview The BTnode is an autonomous wireless communication and computing platform based on a Bluetooth radio and a microcontroller. It serves as a demonstraton platform for research in mobile and ad hoc connected networks (MANETs) and distributed sensor networks. The BTnode has been jointly developed by the Computer Engineering and Networks Laboratory (tik) and the Research Group for Distributed Systems. Currently the BTnode is used in two major projects: NCCR MICS and Smart-Its. BTnode features at a glance
QuickstartBefore you can start off developing applications for the BTnode rev 2.2 you need to
Hardware
Design documentsThe design documents, schematics, data sheets, etc. for the BTnode rev 2.2 (and earlier versions) can be found at http://www.tik.ee.ethz.ch/~beutel/bt_node.html.Connectors
Most connectors provide direct access the microcontroller's external ports (the only exception being the power connector J9 and the Bluetooth PCM connector J7). The diagram on the right shows the mapping of the microcontroller ports to the external connectors. These ports (except the programming port J1) can be used as general-purpose digital io but have other special functions also (such as a UART and analog in for the ADC). All external ports on the BTnode board are 6-pin 1.25mm Molex connectors (socket/ female: 53261, corresponding male plug: 51021). See the picture on the far right or top assembly for the location of the ports. In-System Programming (J1)For programming the BTnode2.2 with the Atmel STK500 (or any other programmer) you will need to make your own programming cable with a Molex 51021 connector. The in-system programming port of the BTnode is J1. See the table below for the ISP-port pin configuration of the BTnode (J1) and the Atmel STK500. The diagram to the right shows how to connect the BTnode's ISP port to the Atmel STK500. 
The cheaper AVR ISP from Atmel has been reported to work also. See http://smart-its.teco.edu/btnode/ for more detail. Note 1: The programmer must supply the operating voltage of 3.3 V to the VTG (target voltage) pin of the BTnode. Make sure you change the default settings of the STK500 accordingly! Note 2: Typically, the BTnode is powered through the programmer (when connected). If however, the BTnode has its own power supply connected during programming, the pin VTG of the programmer MUST NOT be connected to the BTnode. Otherwise the BTnode as well as the programmer may be damaged. Power (J9)The BTnode operates at 3.3 V. It has its own power regulator to reduce battery voltage to the operating voltage, so you can apply various power sources form 3.3 V up to 12 V to the Power connector J9. You may also use the pin 1 (Vcc) and pin 6 (GND) on all other ports (except the in-system programming port J1) as power supply for the BTnode. However, this will bypass the power regulator. Be sure to apply 3.3 V only or you will damage the system! The Vcc and GND pins on the other ports (EXCEPT the in-system programming port J1) may also be used to supply the operating voltage of 3.3 V to power external devices. UART (J4)
The UART (universal asynchronous receiver-transmitter) port is for serial communication. In the UART1 driver the bautrate is currently hardcoded to 57600 with no flow control. If you need to change them, modify and recompile the driver. The BTnode's UART port operates at 3.3 V. That means if you want to connect the BTnode to a PC's RS-232 serial port, which operates at much higher voltage levels (between 3 V and 25 V) you need a level converter, e.g. the IF232 from Elektronikladen (German site, but they have distributors in Germany, Switzerland, Sweden, and other countries). See this diagram how to serially connect the BTnode to a PC using the IF232 level converter. Sensor-board/ BTnode interconnect: i(2+1)c (J5)Use this connector to interconnect sensor-board and BTnode. The communication is based on the i2c bus (aka two-wire interface) plus a 3rd wire. Over the i2c bus, there is a driver-specific protocol (payload data is framed between header (indicating the payload length) and trailer bytes). This protocol became necessary to implement packet transfers over i2c where the length of the data packet is unknown beforehand. The 3rd wire became necessary to trigger communication from the BTnode to the sensor board.
Bluetooth PCM (J7)Connector J7 provides access to the PCM voice interface interface of the Ericsson Bluetooth module. This interface is not needed for data transfers. If you don't know what PCM is you don't need it.Other connectors (J2, J3, J6)The connectors J2, J3, and J6 have no preassigned function and can be used by the application. These connectors are wired directly to the IO pins of the ATmega128 (see table below). Every pin can be used as general purpose IO (GPIO). Additionaly, every pin on the Atmel ATmega128 can be configured for alternate functions (see section I/O Ports in the Atmel ATmega128 datasheet).
In-system programmingFuse-bit settingsBefore you can use the BTnode you have to program the microcontroller's fuse bits. Otherwise the microcontroller, which suffers from the Multiple Personality Syndrome (MPS), thinks it is the less powerfull ATmega 103. As an effect of this, some programs behave randomly while others might still work. Programming the fuse bits needs to be done only once per BTnode. To do so get AVR Studio 4.05 (for Windows only, the latest revision at the time of writing this page) from http://www.atmel.com/atmel/products/prod203.htm. Install it, fire it up and click the "AVR" button in the menubar. In the popup dialog, first set the target voltage VTarget to 3.3 V (in the in the "Board" card), then change the fuse-bit settings (in the "Fuses" card). Check the following boxes:
The fuse bits are set by uisp using the commands: --wr_fuse_e=0xFF --wr_fuse_h=0xC1 --wr_fuse_l=0x8C. This works although reading the fuse bits does not work (uisp-20020626) Uploading your programTo upload an executable to the BTnode you need a hardware programmer (Atmel STK500), a programming cable (see above), programming software, and, of course, the program. As programming software you can either use AVR Studio for Windows (see Fuse-bit settings above) or uisp for Linux and Mac OS X. uisp is included in the tool downloads for Linux and Mac OS X. To upload a BTnode program, its executable needs to be either in the "hex" or "srec" formats. There are examples in the system-software that illustrate how to generate these binary formats from your sources. (Basically they makefiles create them for you.)Development toolsWe provide a binary distribution of all the software tools required to compile your own programms and upload them to the BTnode. There is a binary distribution for Windows, Linux, and Mac OS X:
Development tools documentation
BTnode system softwareThe BTnode system software is basically a library of functions that provide access to the BTnode resources, such as Bluetooth, serial communication, LED, and the like. There is also some documentation. The software is available as a precompiled binary package, as source-code package, and via anonymous CVS. The binary package contains everything you need (e.g., libraries, include files, examples, and documentation) readily made. The source package obviously contains the sources of the system software, so you can have a look at the internals or build the library and documentation yourself. If you need to adapt the library to your needs I recommend retrieving the sources from CVS. The binary package needs to be installed into /usr/local/btnode. To do so, untar the package in /usr/local. You end up with a directory structure like this: ./btnode/ ./btnode/include/.. ./btnode/lib/.. ./btnode/doc/.. ./btnode/examples/..
Latest releaseBinary download package: btnode-posthackfest-20021125.bin.tar.gz Old releases
CVS snapshotcvs -d :pserver:anonymous@vsgr3.inf.ethz.ch:/pub/project/CVSROOT login (no passwd) cvs -d :pserver:anonymous@vsgr3.inf.ethz.ch:/pub/project/CVSROOT \ checkout smart-its Getting startedTo compile your first program for the BTnode cd to /usr/local/btnode/examples/smart-its/avr128 and type make. You should esnd up with a few executable binaries (.srec) for the BTnode. To use the program uispand the STK500 programmer to upload a binary to the BTnode using the following command line:/usr/local/avr/bin/uisp -v=3 -dprog=stk500 -dserial=/dev/ttyS1 -dpart=ATmega128 -mode=s --erase --upload if=helloworld.srec There is some API documentation in your installation directory /usr/local/btnode/doc/smart-its/html/index.html BTnode rev 2.2 Resources
AcknowledgementsMany thanks to: Jan Beutel for designing the latest revision and manageing the production of the BTnode. Oliver Kasten (myself ;-) for much of the software. Matthias Ringwald for providing the binary downloads of the tools for Mac OS X. Thomas Moser and Lukas Karrer for the initial hardware design and software. Most of the drivers are still based on their code. Urs Baer for the latest Bluetooth software. All the others that have in some way contributed. Cheers! |
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